Comparing the pregnancy risks of hyperthyroidism and hypothyroidism: A study of an American population database with more than 200,000 cases

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Our goal was to better understand the implications of these disease processes on pregnancy and compare outcomes in women with hyperthyroidism versus hypothyroidism. Methods We performed a retrospective population-based cohort study using the Health Care Cost and Utilization Project-Nationwide Inpatient Sample. We included all deliveries with maternal hyperthyroidism or hypothyroidism between 2004–2014. We compared pregnancy, delivery, and neonatal outcomes between participants with hyperthyroidism and hypothyroidism. Multivariate logistic regression analysis was used to calculate adjusted-odds-ratios (aOR) and 95% confidence internals (95%CI). Results We studied 16,984 pregnancies with hyperthyroidism, and 184,655 with hypothyroidism. Participants with hyperthyroidism were less likely to have gestational diabetes mellitus (aOR:0.75;95%CI:0.70–0.79), operative vaginal delivery (aOR:0.90;95%CI:0.84–0.97), and cesarean section (aOR:0.89;95%CI:0.86–0.93) when compared to participants with hypothyroidism. They were more likely to have preterm premature rupture of membranes (aOR:1.30;95%CI:1.15–1.47), preterm delivery (aOR:1.37;95%CI:1.30–1.44), abruptio placenta (aOR:1.43;95%CI:1.26–1.63), wound complications (aOR:1.30;95%CI:1.06–1.59) and blood transfusions (aOR:1.35;95%CI:1.19–1.54). Infants born to hyperthyroid mothers were likelier to be small for gestational age (aOR:1.47;95%CI:1.35–1.59) compared to infants born to hypothyroid mothers. There were no differences for gestational hypertensive disorders, chorioamnionitis, hysterectomy, postpartum hemorrhage, maternal death, and congenital anomalies (p > 0.05). Conclusions Hyperthyroidism was associated with increased risk of pregnancy outcomes compared to hypothyroidism, with a few exceptions, particularly rates of gestational diabetes and caesarean section which were decreased in this group. Our study is novel as it compares the risks of hyperthyroidism versus hypothyroidism during pregnancy, thereby providing a new perspective to the existing literature. Hypothyroidism Hyperthyroidism Pregnancy outcomes Delivery outcomes Neonatal outcomes INTRODUCTION Normal thyroid function in pregnancy is important for adequate maternal health and fetal development [ 1 , 2 ]. A 2019 meta-analysis estimated the prevalence of overt hypothyroidism during pregnancy at 0.50% and of overt hyperthyroidism during the first trimester of pregnancy at 0.91% [ 3 ]. The reported prevalence of thyroid dysfunction during pregnancy varies, in part due to the lack of standardized thyroid stimulating hormone (TSH) ranges. The American Thyroid Association recommends establishing the upper limit for TSH based on the values of local populations [ 4 ]. Primary hypothyroidism is a common disorder worldwide, with the most common cause being late sequelae Hashimoto’s thyroiditis in iodine-sufficient regions, characterized by high concentrations of anti-thyroid and antithyroglobulin antibodies [ 5 ]. In reproductive-age women, hyperthyroidism is most frequently attributed to Graves’ disease [ 6 ], an autoimmune condition where thyroid stimulating hormone (TSH)-receptor autoantibodies cause excessive production of thyroid hormone [ 7 ]. Most women with low TSH measurements in the first trimester subsequently revert to normal thyroid function because of gestational transient thyrotoxicosis due to high levels of hCG, complexifying the diagnosis of hyperthyroidism during pregnancy [ 8 ]. The American Thyroid Association guidelines cite an association between thyroid dysfunction during pregnancy and various adverse maternal and neonatal outcomes [ 4 ]. Maternal overt hypothyroidism is associated with an increased prevalence of obstetrical complications including spontaneous abortions, preeclampsia, gestational hypertension, placental abruption, and preterm deliveries [ 9 ]. Complications of overt maternal hyperthyroidism are less well described but include preeclampsia, premature delivery, and offspring being born small for gestational age [ 10 ]. More severe complications like thyroid storm and heart failure have been reported in untreated cases [ 10 ]. While pregnancy and neonatal outcomes have been compared between mothers with hyper- or hyperthyroidism and unaffected mothers, very few studies or none have contrasted the risk of one versus the other. Determining the relative risk can guide resource allocation in screening and caring for thyroid disorders in pregnancy to limit the event of adverse outcomes. Establishing the relative risk will refine practitioners’ clinical judgement when they encounter patient with thyroid disorders, as they will be able to better contrast both pathologies and their possible complications. While the pathogenesis of both conditions is different, the clinical algorithm addressing thyroid conditions has overlap [ 4 ], and better understanding of relative risk of adverse outcomes related to hyper versus hypothyroidism will inform risk management during pregnancy. Although, these two diseases are not interchangeable, this academic undertaking will provide further understanding of the implications of these diseases in pregnancy. Therefore, our study aimed to compare the relative risk of adverse pregnancy, delivery, and neonatal outcomes in women with hyperthyroidism versus hypothyroidism in a large American database. METHODS We conducted a retrospective population-based study utilizing data collected between 2004 and 2014 inclusively, from the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample (HCUP-NIS). The HCUP-NIS is the largest inpatient sample database in the United States and comprises hospital inpatient stays submitted by hospitals in 48 states and the District of Columbia. This database is accessible online to the public (see “Data availability statement”). Each year, the database provides information about seven million inpatient stays, including patient characteristics, diagnoses, and procedures. The data is representative of ~ 20% of admissions to American hospitals and geographically represents over 96% of the population in the United States. We did not include the data from 2015 to 2018 since they are organized by ICD-10 codes which are incomparable with ICD-9 codes. We evaluated deliveries using the international classification of diseases, ninth edition, clinical modification codes for delivery-related discharge diagnosis (650.xx, 677.xx, 651.xx–676.xx, where the fifth digit is 0, 1, or 2) and birth-related procedural diagnosis (72.x, 73.x, 74.0–74.2). We limited our study group to the admissions that ended with delivery of fetuses at least 20 weeks of gestational age or maternal death, to guarantee that multiple admissions in the same pregnancy would be excluded. It should be noted that the database as organized does not include miscarriage or termination of pregnancy data. Within this group, all women with a diagnosis of hyperthyroidism were selected as the index group and were identified using ICD-9 diagnostic codes 242.0x, 242.1x, 242.2x, 242.3x, 242.4x, 242.8x, and 242.9x. All women with a diagnosis of hypothyroidism were selected as the comparison group and were identified using ICD-9 diagnostic codes 244 (244.0, 244.1, 244.2, 244.3, 244.8, 244.9), 245.2. Women with a diagnosis of congenital hypothyroidism were excluded. Baseline characteristics included the following: patient age, race, income, insurance type, obesity (body mass index ≥ 30 kg/m 2 ), previous cesarian section, chronic hypertension and pregestational diabetes mellitus, illicit drug use, tobacco smoking status, and multiple gestations (more than one fetus concurrently). Pregnancy outcomes evaluated included hypertensive disorders of pregnancy (pregnancy-induced hypertension, gestational hypertension, and preeclampsia/eclampsia), gestational diabetes mellitus, and placenta previa. Delivery outcomes evaluated included preterm premature of the membranes (PPROM), preterm delivery, placental abruption, chorioamnionitis, operative vaginal delivery, cesarian section (CS), spontaneous vaginal delivery (SVD), hysterectomy, post-partum hemorrhage (PPH), wound complication, maternal death, and transfusion. Other outcomes evaluated included maternal infection, deep vein thrombosis (DVT), pulmonary embolism, venous thromboembolism (VTE), and disseminated intravascular coagulation (DIC). Neonatal outcomes included small for gestational age (SGA) infants, intrauterine fetal death (IUFD), and congenital anomalies. Statistical analysis An initial analysis was performed to identify the prevalence of pregnant women with hyperthyroidism and hypothyroidism over the entire duration of the study. We then compared baseline clinical and demographic characteristics between women with hyperthyroidism to those with hypothyroidism, using chi-squared tests. Subsequently, logistic regression analyses were conducted to explore comparisons between hyperthyroidism and hypothyroidism in pregnancy concerning obstetrical and neonatal outcomes through the estimation of crude odds ratios (OR) and 95% confidence intervals (95% CI), without controlling for confounding effects. The regression models were then adjusted for the potential confounding effects of maternal demographics, pre-existing clinical characteristics, and concurrently occurring characteristics to generate adjusted odds ratios (aOR) and 95% CI. A confounder was determined if there was a significant difference (p < 0.05) between participants with hyperthyroidism and hypothyroidism for demographics or pre-pregnancy diseases, as listed above. All analyses were performed using SPSS 23.0 (IBM Corporation, Chicago, IL, USA). Pregnancy outcomes were adjusted for age, race, insurance plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, and pregestational diabetes mellitus. Delivery outcomes were adjusted for the same maternal characteristics as pregnancy above with the addition of pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa. Fetal outcomes were adjusted for the same confounders as delivery outcomes. RESULTS There were 9,096,788 unique births between 2004 and 2014. Of those, 16,984 included pregnancies had a documented diagnosis of hyperthyroidism and 184,655 had a documented diagnosis of hypothyroidism. In this population, the prevalence of hyperthyroidism and hypothyroidism was 0.19% and 2.0% respectively. Baseline demographic characteristics for our population are summarized in Table 1 . Women with hyperthyroidism were more likely to be younger and Black or Hispanic as opposed to women with hypothyroidism, who were more likely to be older and Caucasian. Women with hyperthyroidism were more likely to have a lower income and be covered by Medicaid insurance compared to women with hypothyroidism, who had higher incomes and were covered by private health insurance. Women with hyperthyroidism were less likely to be obese and to have pregestational diabetes mellitus compared to women with hypothyroidism. Furthermore, these women were more likely to have chronic hypertension, to consume illicit drugs, and to smoke tobacco during pregnancy compared to the group with a diagnosis of hypothyroidism. There were no differences between the two groups concerning the rates of previous caesarean section and multiple gestation pregnancies. Table 1 Maternal Characteristics Hyperthyroidism N = 16984 (%) Hypothyroidism N = 184655 (%) P-value Age (years) < 25 25.2 13.6 < 0.001 25–34 52.7 56.2 ≥ 35 22.1 30.3 Race White 45.6 65.4 < 0.001 Black 22.5 9.7 Hispanic 18.3 13.4 Asian and Pacific 8.4 6.1 Native American 0.8 0.6 Other 3.8 4.2 Income quartiles Less than 39,000 22.7 14.9 < 0.001 $ 39,000–47,999 31.5 27.7 $ 48,000–62,999 27.7 30.4 $ 63,000 or more 18.0 27.0 Plan type Medicare 0.88 0.9 < 0.001 Medicaid 39.0 20.0 Private including HMO 54.7 74.5 Self Pay 2.3 1.6 No charge 0.14 0.1 Other 2.9 2.9 Body mass index Obese 4.5 7.4 < 0.001 Previous Cesarean Section 19.8 20.7 .007 Chronic hypertension 5.7 4.2 < 0.001 Pregestational diabetes mellitus 2.1 3.4 < 0.001 Illicit Drug Use 2.0 0.7 < 0.001 Tobacco Smoking During Pregnancy 6.1 3.4 < 0.001 Multiple Gestation 3.2 3.0 0.096 The crude and adjusted odds ratios for the association between pregnancy and delivery outcomes and their respective prevalence in each group are outlined in Table 2 . Regarding pregnancy outcomes, compared with participants with hypothyroidism, participants with hyperthyroidism were less likely to suffer from gestational diabetes mellitus with an OR of 0.75 and 1.25 times more likely to have a placenta previa, after controlling for the confounding effect of age, race, income level, medical insurance type, obesity, chronic hypertension, pregestational diabetes mellitus, illicit drug use, and tobacco smoking. There were no differences between the two groups for hypertensive disorders of pregnancy (gestational hypertension and preeclampsia). Table 2 Pregnancy and delivery outcomes Hyperthyroidism (%) Hypothyroidism (%) Crude OR (95% CI) Adjusted OR (95% CI) Adjusted p-value Pregnancy outcomes a Pregnancy-induced hypertension 10.3 9.9 1.02 (0.96–1.08) 1.05 (0.997–1.11) 0.06 Gestational hypertension 4.0 4.3 0.93 (0.86–1.01) 1.00 (0.93–1.09) 0.93 Preeclampsia 4.7 4.6 1.03 (0.95–1.11) 1.05 (0.98–1.14) 0.18 Eclampsia 0.1 0.1 1.31 (0.75–2.29) 1.16 (0.66–2.05) 0.61 Preeclampsia and Eclampsia superimposed on preexisting hypertension 1.1 1.44 (1.27–1.64) 1.15 (0.99–1.33) 0.07 Gestational diabetes mellitus 7.9 10.3 0.75 (0.70–0.79) 0.75 (0.70–0.79) < 0.001 Placenta previa 0.9 0.8 1.15 (0.97–1.35) 1.25 (1.06–1.48) 0.009 Delivery outcomes b Preterm premature rupture of membranes 1.7 1.4 1.28 (1.13–1.44) 1.30 (1.15–1.47) < 0.001 Preterm delivery 11.6 8.3 1.45 (1.38–1.52) 1.37 (1.30.1.44) < 0.001 Abruptio placenta 1.7 1.1 1.58 (1.39–1.78) 1.43 (1.26–1.63) < 0.001 Chorioamnionitis 2.0 1.7 1.16 (1.03–1.30) 1.06 (0.94–1.19) 0.36 Operative vaginal delivery 4.7 0.97 (0.90–1.04) 0.90 (0.84–0.97) 0.004 Cesarean section 37.7 41.8 0.84 (0.82–0.87) 0.89 (0.86–0.93) < 0.001 Spontaneous vaginal delivery 57.8 53.5 1.19 (1.15–1.23) 1.12 (1.08–1.17) < 0.001 Hysterectomy 0.2 0.1 1.18 (0.80–1.74) 1.18 (0.78–1.79) 0.43 Post-partum hemorrhage 3.0 3.1 0.98 (0.90–1.08) 0.95 (0.86–1.04) 0.24 Wound complications 0.6 0.5 1.18 (0.97–1.45) 1.30 (1.06–1.59) 0.01 Maternal death 0 0 2.72 (0.77–9.63) 2.14 (0.57–8.03) 0.26 Blood transfusion 1.7 1.1 1.53 (1.35–1.73) 1.35 (1.19–1.54) < 0.001 Others c Maternal infection 2.5 2.0 1.25 (1.13–1.39) 1.12 (1.01–1.25) 0.03 Deep vein thrombosis 0.1 0.1 1.59 (0.96–2.65) 1.55 (0.92–2.63) 0.10 Pulmonary embolism 0.1 0 2.22 (1.16–4.24) 1.94 (0.99–3.82) 0.05 Venous thromboembolism 0.2 0.1 1.78 (1.19–2.68) 1.68 (1.10–2.56) 0.02 Disseminated intravascular coagulation 0.3 0.2 1.19 (0.89–1.59) 1.15 (0.85–1.55) 0.38 a. Pregnancy outcome: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa. b. Delivery outcomes: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa. c. Others: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa. Abbreviations: OR, odds ratio; CI, confidence interval. Regarding delivery outcomes, after controlling for the same confounding effects, women with hyperthyroidism were 1.3 times more likely to suffer preterm premature rupture of membranes, 1.37 times more likely to deliver prematurely, 1.43 times more likely to have a placental abruption, 1.12 times more likely to have a spontaneous vaginal delivery, 1.30 times more likely to have wound complications, 1.35 times more likely to require blood transfusions, 1.12 times more likely to have a maternal infection, and 1.68 times more likely to have a venous thromboembolism as compared to women with hypothyroidism. Women with hyperthyroidism were less likely to have an operative vaginal delivery and were less likely to undergo a caesarean section compared to women with hypothyroidism. Differences between outcomes were not statistically different between the two groups regarding rates of chorioamnionitis, hysterectomy, postpartum hemorrhage, maternal deaths, deep vein thrombosis, pulmonary embolism, and disseminated intravascular coagulation (p ≥ 0.05). The crude and adjusted odds ratio for the association between neonatal outcomes and their prevalence in each group are outlined in Table 3 . Women with hyperthyroidism were 1.47x more likely to have a baby that was small for gestation age, and 1.55 times more likely to have an intra-uterine fetal death. There was no difference in the prevalence of congenital anomalies between the two groups (p ≥ 0.05). Table 3 Neonatal outcomes a Hyperthyroidism (%) Hypothyroidism (%) Crude OR (95% CI) Adjusted OR (95% CI) Adjusted p-value Small for gestational age infant 4.4 2.6 1.71 (1.58–1.85) 1.47 (1.35–1.59) < 0.001 Intrauterine fetal death 0.7 0.4 1.81 (1.49–2.19) 1.55 (1.27–1.89) < 0.001 Congenital Anomalies 0.6 0.8 0.80 (0.66–0.98) 0.85 (0.70–1.04) 0.11 a. Fetal outcomes: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa. Abbreviations: OR, odds ratio; CI, confidence interval. DISCUSSION Our study was based on data from a large American population and includes 16,984 pregnancies with a documented diagnosis of hyperthyroidism and 184,655 pregnancies with a documented diagnosis of hypothyroidism. Cases of pregnancies with a diagnosis of hyperthyroidism were compared to pregnancies with a diagnosis of hypothyroidism, who acted as the control group. Maternal characteristics, including demographics and pre-pregnancy comorbidities, differed between the two groups, which was accounted for in the adjusted analysis. Participants with hyperthyroidism had a small but significative increased risk of certain pregnancy and delivery outcomes when compared to participants with hypothyroidism. Numerous studies have explored thyroid dysfunction during pregnancy and its association with adverse outcomes relative to the general population. Our study is novel, as it compares the risks of hyperthyroidism versus hypothyroidism during pregnancy, thereby providing a new perspective to the existing literature. These findings will provide additional insight to the clinical judgment of practitioners caring for thyroid disorders in pregnancy. Pregnancy outcomes Regarding pregnancy outcomes, the American Thyroid Association, in its guidelines during pregnancy, mentions an increased risk of hypertensive disorders of pregnancy for both women with hyperthyroidism and hypothyroidism [ 4 ]. We reported no significant difference between the two groups regarding rates of pregnancy-induced hypertension, gestational hypertension, preeclampsia, and eclampsia. In Lancet reviews, gestational diabetes mellitus was associated with hypothyroidism during pregnancy [ 9 ], while it was not noted in the context of hyperthyroidism during pregnancy [ 10 ]. Our study confirmed this finding and demonstrated that women with hypothyroidism were more likely to have gestational diabetes mellitus compared to women with hyperthyroidism. Our study supports the established literature that the studied thyroid disorders are associated with hypertensive disorders of pregnancy to a similar magnitude, and that hypothyroidism has greater risks of gestational diabetes mellitus than hyperthyroidism. Delivery outcomes Thyroid hormone is important for adequate trophoblast function and migration [ 11 , 12 ], and proper placental implantation [ 13 ]. Abnormal placentation has been suggested as a cause of idiopathic preterm birth [ 14 ], and other pregnancy complications in thyroid disorders [ 15 ]. Partially due to the mechanisms described above, delivery complications are well described in women with thyroid dysfunction, but the relative risk of hyper- versus hypothyroidism is seldom reported. In a prospective population-based cohort study, placental abruption was reported in a group of participants with iatrogenic hypothyroidism [ 16 ]. In our study population, the increased risk of placental abruption was seen in women with hyperthyroidism, as compared to women with hypothyroidism. In a meta-analysis including 14 cohort studies and 1 case-control for a total of 1,523,704 participants, preterm birth was more frequent in children born to mothers with a diagnosis of thyroid dysfunction compared to the general population. In this meta-analysis, the adjusted risk was slightly greater in participants with a diagnosis of hyperthyroidism (OR 1.24) than in participants with a diagnosis of hypothyroidism (OR 1.19) [ 17 ]. This is concordant with our findings, where the risk of preterm birth was 1.4-fold higher in participants with hyperthyroidism when compared to hypothyroidism and higher than the magnitude reported in the meta-analysis. In a Chinese population-based cohort study of 184,611 women, high TSH levels, between 4.29 and 10.00 IU/L, hypothyroidism was associated with an increased risk of cesarean delivery and operative delivery when compared to the general population [ 18 ]. Participants with low TSH were not evaluated [ 19 ]. Similarly in our study, participants with hypothyroidism were more likely to undergo cesarean section or operative vaginal delivery compared to hyperthyroid participants, who were more likely to undergo spontaneous vaginal delivery. One prospective population-based cohort study reported ICU admission as a delivery-associated complication of primary hypothyroidism and hyperthyroidism [ 16 ]. The causes of admission were not listed. In our study, outcomes related to maternal morbidity such as chorioamnionitis, hysterectomy, postpartum hemorrhage, venous thromboembolism, disseminated intra coagulation and maternal death were comparable between the two groups. Risks were slightly higher among the hyperthyroid group for wound complications, blood transfusions, and maternal infections. Many of these risks could lead to ICU admission, which was not coded for in the database. Neonatal outcomes In a Danish population-based study comparing birth weight of infants born to mothers with thyroid dysfunction, maternal hypothyroidism was associated with infants born large for gestational age, while hyperthyroidism was associated with infants born small for gestational age [ 20 ]. We obtained similar findings, as infants born to hyperthyroid mothers were more likely to be small for gestational age when compared to those born to hypothyroid mothers. Both hypo- and hyperthyroidism have been described to be associated with an increased risk of stillbirth compared to the general population [ 21 ]. A Turkish cross-sectional study of 1519 participants reported increased risks of late fetal losses in hypothyroid women [ 22 ]. In our study, the risk of intrauterine fetal death was increased in the hyperthyroid group than in the hypothyroid group. Studies report a small but significant increase in congenital anomalies among infants born to hypothyroid mothers [ 23 , 24 ]. A recent meta-analysis suggested that both overt hyperthyroidism and antithyroid drugs can increase the risk of congenital anomalies [ 25 ]. Our study identified no difference in the rates of congenital anomalies between infants born to hypo- and hyperthyroid mothers. Strengths and limitations Our study has several limitations, the most important being that it was a retrospective analysis with unavailable TSH levels and other laboratory values. We could not verify the diagnosis of hyperthyroidism or hypothyroidism and whether they were posed in a consistent manner, or if diagnoses varied based on the diagnosing physician. Transient gestational thyrotoxicosis secondary to beta-hCG further complexifies the diagnosis of hyperthyroidism[ 8 ]. As this presentation resolves during the first trimester, it should not lead to a misclassification of healthy subjects as hyperthyroid patients at the time of the birth of their child. It is unlikely that normal subjects were included in the analysis, however, diagnostic heterogeneity likely existed. In 2011, which is included in our study period, the American Thyroid Association (ATA) first published guidelines on the diagnosis and management of thyroid disease in pregnancy, which were updated in 2017[ 4 ]. Updated guidelines likely have changed diagnosis and management practices, but as this is a population-based study, the estimated risks likely represent practices as they evolve with guidelines. It should also be noted that all women diagnosed as hypothyroid prior to 2017 would also have been included in the diagnoses with the revised guidelines. As laboratory values are unavailable, we are unable to reclassify participants according to current guidelines. Further studies beyond the scope of this article will be required to assess the impact of evolving guidelines on practice and adverse pregnancy outcomes. Another limitation is that we were unable to ascertain medication use and compliance during pregnancy. This prevents us from studying the effects of medication type and compliance on the outcomes. Nonetheless, as this is a population-based study, we can estimate that the participants reflect the use and compliance of medications in the general population. We could not include the data from 2015 and onwards dye to alterations in the ICD coding system which are incomparable with ICD-9 codes. The odds ratios we estimated are of small magnitude. This informs us that the increased risks generally associated with hyperthyroidism when compared to hypothyroidism are only mildly elevated. Strengths of our study include its magnitude, with more than 200,000 cases studied over the span of 10 years. The power of our study allows us to control for potential confounders. The findings are in alignment with the published literature on thyroid disorders during pregnancy and provide an interesting insight into the comparison between hypo- and hyperthyroidism. This is likely the first population-based study to perform such a comparison. In conclusion, our large population-based study from the American Healthcare Cost and Utilization Project-Nationwide Inpatient Sample (HCUP-NIS) database provides novel and interesting insight into thyroid disorders in pregnancy, with an overall small but significant increase in the risk of adverse outcomes for participants with hyperthyroidism when compared to hypothyroidism. These results provide insight into the understanding of thyroid disorders during pregnancy. Declarations Competing Interests The authors declare no conflict of interest. Ethics approval This study used exclusively publicly accessible, anonymized data; therefore, according to the Tri-Council Policy Statement, intuitional review board approval was not required. The data that support the findings of this study are available in NIS Database Documentation at https://hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp and are available to the public. Funding We have no sources of funding to declare. Acknowledgements None. References Korevaar TIM, Medici M, Visser TJ, Peeters RP (2017) Thyroid disease in pregnancy: new insights in diagnosis and clinical management. Nat Rev Endocrinol. https://doi.org/10.1038/nrendo.2017.93 Vandana KA, Khatuja R, Mehta S (2014) Thyroid dysfunction during pregnancy and in postpartum period: treatment and latest recommendations. 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Eur Thyroid J. https://doi.org/10.1159/000350513 Stagnaro-Green A (2011) Overt hyperthyroidism and hypothyroidism during pregnancy. Clin Obstet Gynecol. https://doi.org/10.1097/GRF.0b013e3182272f32 Feki M, Omar S, Menif O, Tanfous NB, Slimane H, Zouari F et al (2008) Thyroid disorders in pregnancy: frequency and association with selected diseases and obstetrical complications in Tunisian women. Clin Biochem. https://doi.org/10.1016/j.clinbiochem.2008.05.002 Turunen S, Vääräsmäki M, Männistö T, Hartikainen AL, Lahesmaa-Korpinen AM, Gissler M et al (2019) Pregnancy and Perinatal Outcome Among Hypothyroid Mothers: A Population-Based Cohort Study. https://doi.org/10.1089/thy.2018.0311 . Thyroid Wikner BN, Sparre LS, Stiller CO, Källén B, Asker C (2008) Maternal use of thyroid hormones in pregnancy and neonatal outcome. Acta Obstet Gynecol Scand. https://doi.org/10.1080/00016340802075103 Morales DR, Fonkwen L, Nordeng HME (2021) Antithyroid drug use during pregnancy and the risk of birth defects in offspring: systematic review and meta-analysis of observational studies with methodological considerations. Br J Clin Pharmacol. https://doi.org/10.1111/bcp.14805 Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Major revisions 14 Dec, 2025 Reviewers agreed at journal 25 Nov, 2025 Reviewers invited by journal 25 Nov, 2025 Editor invited by journal 25 Nov, 2025 Editor assigned by journal 19 Nov, 2025 First submitted to journal 18 Nov, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8148224","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":550589187,"identity":"674fa05d-67b2-48ef-bf0c-7dd5d27d1f61","order_by":0,"name":"Noah Margolese","email":"data:image/png;base64,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","orcid":"https://orcid.org/0009-0004-1094-3085","institution":"Universite de Sherbrooke Faculté de Médecine et des Sciences de la Santé: Universite de Sherbrooke Faculte de medecine et des sciences de la sante","correspondingAuthor":true,"prefix":"","firstName":"Noah","middleName":"","lastName":"Margolese","suffix":""},{"id":550589188,"identity":"a4ec48a4-5dde-4b76-83a7-2c38adf81c98","order_by":1,"name":"Juliette St-Georges","email":"","orcid":"","institution":"Department of Obstetrics and Gynecology, University of Montreal","correspondingAuthor":false,"prefix":"","firstName":"Juliette","middleName":"","lastName":"St-Georges","suffix":""},{"id":550589189,"identity":"0f9b494e-bf7d-4d71-a191-f5d54d0baa2e","order_by":2,"name":"Ahmad Badeghiesh","email":"","orcid":"","institution":"Department of Obstetrics and Gynecology, King Abdulaziz University","correspondingAuthor":false,"prefix":"","firstName":"Ahmad","middleName":"","lastName":"Badeghiesh","suffix":""},{"id":550589190,"identity":"f3c94f30-e32b-40a7-add3-32806cc25c51","order_by":3,"name":"Haitham Baghlaf","email":"","orcid":"","institution":"Department of Obstetrics and Gynecology, International Medical Center","correspondingAuthor":false,"prefix":"","firstName":"Haitham","middleName":"","lastName":"Baghlaf","suffix":""},{"id":550589191,"identity":"6e4775ea-d34e-4967-989d-e0c9c213fce8","order_by":4,"name":"Michael H. 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A 2019 meta-analysis estimated the prevalence of overt hypothyroidism during pregnancy at 0.50% and of overt hyperthyroidism during the first trimester of pregnancy at 0.91% [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The reported prevalence of thyroid dysfunction during pregnancy varies, in part due to the lack of standardized thyroid stimulating hormone (TSH) ranges. The American Thyroid Association recommends establishing the upper limit for TSH based on the values of local populations [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Primary hypothyroidism is a common disorder worldwide, with the most common cause being late sequelae Hashimoto\u0026rsquo;s thyroiditis in iodine-sufficient regions, characterized by high concentrations of anti-thyroid and antithyroglobulin antibodies [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. In reproductive-age women, hyperthyroidism is most frequently attributed to Graves\u0026rsquo; disease [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], an autoimmune condition where thyroid stimulating hormone (TSH)-receptor autoantibodies cause excessive production of thyroid hormone [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Most women with low TSH measurements in the first trimester subsequently revert to normal thyroid function because of gestational transient thyrotoxicosis due to high levels of hCG, complexifying the diagnosis of hyperthyroidism during pregnancy [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThe American Thyroid Association guidelines cite an association between thyroid dysfunction during pregnancy and various adverse maternal and neonatal outcomes [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Maternal overt hypothyroidism is associated with an increased prevalence of obstetrical complications including spontaneous abortions, preeclampsia, gestational hypertension, placental abruption, and preterm deliveries [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Complications of overt maternal hyperthyroidism are less well described but include preeclampsia, premature delivery, and offspring being born small for gestational age [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. More severe complications like thyroid storm and heart failure have been reported in untreated cases [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. While pregnancy and neonatal outcomes have been compared between mothers with hyper- or hyperthyroidism and unaffected mothers, very few studies or none have contrasted the risk of one versus the other. Determining the relative risk can guide resource allocation in screening and caring for thyroid disorders in pregnancy to limit the event of adverse outcomes. Establishing the relative risk will refine practitioners\u0026rsquo; clinical judgement when they encounter patient with thyroid disorders, as they will be able to better contrast both pathologies and their possible complications. While the pathogenesis of both conditions is different, the clinical algorithm addressing thyroid conditions has overlap [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], and better understanding of relative risk of adverse outcomes related to hyper versus hypothyroidism will inform risk management during pregnancy. Although, these two diseases are not interchangeable, this academic undertaking will provide further understanding of the implications of these diseases in pregnancy. Therefore, our study aimed to compare the relative risk of adverse pregnancy, delivery, and neonatal outcomes in women with hyperthyroidism versus hypothyroidism in a large American database.\u003c/p\u003e"},{"header":"METHODS","content":"\u003cp\u003eWe conducted a retrospective population-based study utilizing data collected between 2004 and 2014 inclusively, from the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample (HCUP-NIS). The HCUP-NIS is the largest inpatient sample database in the United States and comprises hospital inpatient stays submitted by hospitals in 48 states and the District of Columbia. This database is accessible online to the public (see \u0026ldquo;Data availability statement\u0026rdquo;). Each year, the database provides information about seven million inpatient stays, including patient characteristics, diagnoses, and procedures. The data is representative of ~\u0026thinsp;20% of admissions to American hospitals and geographically represents over 96% of the population in the United States. We did not include the data from 2015 to 2018 since they are organized by ICD-10 codes which are incomparable with ICD-9 codes.\u003c/p\u003e\u003cp\u003eWe evaluated deliveries using the international classification of diseases, ninth edition, clinical modification codes for delivery-related discharge diagnosis (650.xx, 677.xx, 651.xx\u0026ndash;676.xx, where the fifth digit is 0, 1, or 2) and birth-related procedural diagnosis (72.x, 73.x, 74.0\u0026ndash;74.2). We limited our study group to the admissions that ended with delivery of fetuses at least 20 weeks of gestational age or maternal death, to guarantee that multiple admissions in the same pregnancy would be excluded. It should be noted that the database as organized does not include miscarriage or termination of pregnancy data.\u003c/p\u003e\u003cp\u003eWithin this group, all women with a diagnosis of hyperthyroidism were selected as the index group and were identified using ICD-9 diagnostic codes 242.0x, 242.1x, 242.2x, 242.3x, 242.4x, 242.8x, and 242.9x. All women with a diagnosis of hypothyroidism were selected as the comparison group and were identified using ICD-9 diagnostic codes 244 (244.0, 244.1, 244.2, 244.3, 244.8, 244.9), 245.2. Women with a diagnosis of congenital hypothyroidism were excluded.\u003c/p\u003e\u003cp\u003eBaseline characteristics included the following: patient age, race, income, insurance type, obesity (body mass index\u0026thinsp;\u0026ge;\u0026thinsp;30 kg/m\u003csup\u003e2\u003c/sup\u003e), previous cesarian section, chronic hypertension and pregestational diabetes mellitus, illicit drug use, tobacco smoking status, and multiple gestations (more than one fetus concurrently).\u003c/p\u003e\u003cp\u003ePregnancy outcomes evaluated included hypertensive disorders of pregnancy (pregnancy-induced hypertension, gestational hypertension, and preeclampsia/eclampsia), gestational diabetes mellitus, and placenta previa. Delivery outcomes evaluated included preterm premature of the membranes (PPROM), preterm delivery, placental abruption, chorioamnionitis, operative vaginal delivery, cesarian section (CS), spontaneous vaginal delivery (SVD), hysterectomy, post-partum hemorrhage (PPH), wound complication, maternal death, and transfusion. Other outcomes evaluated included maternal infection, deep vein thrombosis (DVT), pulmonary embolism, venous thromboembolism (VTE), and disseminated intravascular coagulation (DIC). Neonatal outcomes included small for gestational age (SGA) infants, intrauterine fetal death (IUFD), and congenital anomalies.\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eAn initial analysis was performed to identify the prevalence of pregnant women with hyperthyroidism and hypothyroidism over the entire duration of the study. We then compared baseline clinical and demographic characteristics between women with hyperthyroidism to those with hypothyroidism, using chi-squared tests. Subsequently, logistic regression analyses were conducted to explore comparisons between hyperthyroidism and hypothyroidism in pregnancy concerning obstetrical and neonatal outcomes through the estimation of crude odds ratios (OR) and 95% confidence intervals (95% CI), without controlling for confounding effects. The regression models were then adjusted for the potential confounding effects of maternal demographics, pre-existing clinical characteristics, and concurrently occurring characteristics to generate adjusted odds ratios (aOR) and 95% CI. A confounder was determined if there was a significant difference (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) between participants with hyperthyroidism and hypothyroidism for demographics or pre-pregnancy diseases, as listed above. All analyses were performed using SPSS 23.0 (IBM Corporation, Chicago, IL, USA). Pregnancy outcomes were adjusted for age, race, insurance plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, and pregestational diabetes mellitus. Delivery outcomes were adjusted for the same maternal characteristics as pregnancy above with the addition of pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa. Fetal outcomes were adjusted for the same confounders as delivery outcomes.\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eThere were 9,096,788 unique births between 2004 and 2014. Of those, 16,984 included pregnancies had a documented diagnosis of hyperthyroidism and 184,655 had a documented diagnosis of hypothyroidism. In this population, the prevalence of hyperthyroidism and hypothyroidism was 0.19% and 2.0% respectively. Baseline demographic characteristics for our population are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Women with hyperthyroidism were more likely to be younger and Black or Hispanic as opposed to women with hypothyroidism, who were more likely to be older and Caucasian. Women with hyperthyroidism were more likely to have a lower income and be covered by Medicaid insurance compared to women with hypothyroidism, who had higher incomes and were covered by private health insurance. Women with hyperthyroidism were less likely to be obese and to have pregestational diabetes mellitus compared to women with hypothyroidism. Furthermore, these women were more likely to have chronic hypertension, to consume illicit drugs, and to smoke tobacco during pregnancy compared to the group with a diagnosis of hypothyroidism. There were no differences between the two groups concerning the rates of previous caesarean section and multiple gestation pregnancies.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eMaternal Characteristics\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHyperthyroidism\u003c/p\u003e\u003cp\u003eN\u0026thinsp;=\u0026thinsp;16984\u003c/p\u003e\u003cp\u003e(%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHypothyroidism\u003c/p\u003e\u003cp\u003eN\u0026thinsp;=\u0026thinsp;184655\u003c/p\u003e\u003cp\u003e(%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eP-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge (years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e25.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e13.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"2\" rowspan=\"3\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e25\u0026ndash;34\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e52.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e56.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e22.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRace\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWhite\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e45.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e65.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"5\" rowspan=\"6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlack\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e22.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e9.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHispanic\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e18.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e13.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAsian and Pacific\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e8.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e6.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNative American\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOther\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4.2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIncome quartiles\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLess than 39,000\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e22.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e14.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"3\" rowspan=\"4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cspan\u003e$\u003c/span\u003e39,000\u0026ndash;47,999\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e31.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e27.7\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cspan\u003e$\u003c/span\u003e48,000\u0026ndash;62,999\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e27.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e30.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cspan\u003e$\u003c/span\u003e63,000 or more\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e18.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e27.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlan type\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMedicare\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.88\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\" morerows=\"5\" rowspan=\"6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMedicaid\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e39.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e20.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrivate including HMO\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e54.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e74.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSelf Pay\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.6\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNo charge\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOther\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2.9\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBody mass index\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eObese\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e7.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePrevious Cesarean Section\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e19.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e20.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e.007\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChronic hypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e5.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePregestational diabetes mellitus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIllicit Drug Use\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eTobacco Smoking During Pregnancy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e6.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMultiple Gestation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e3.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.096\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eThe crude and adjusted odds ratios for the association between pregnancy and delivery outcomes and their respective prevalence in each group are outlined in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Regarding pregnancy outcomes, compared with participants with hypothyroidism, participants with hyperthyroidism were less likely to suffer from gestational diabetes mellitus with an OR of 0.75 and 1.25 times more likely to have a placenta previa, after controlling for the confounding effect of age, race, income level, medical insurance type, obesity, chronic hypertension, pregestational diabetes mellitus, illicit drug use, and tobacco smoking. There were no differences between the two groups for hypertensive disorders of pregnancy (gestational hypertension and preeclampsia).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003ePregnancy and delivery outcomes\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHyperthyroidism\u003c/p\u003e\u003cp\u003e(%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHypothyroidism\u003c/p\u003e\u003cp\u003e(%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCrude OR\u003c/p\u003e\u003cp\u003e(95% CI)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAdjusted OR\u003c/p\u003e\u003cp\u003e(95% CI)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAdjusted\u003c/p\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003ePregnancy outcomes\u003c/b\u003e \u003csup\u003e\u003cb\u003ea\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePregnancy-induced hypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e10.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e9.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.02\u003c/p\u003e\u003cp\u003e(0.96\u0026ndash;1.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.05\u003c/p\u003e\u003cp\u003e(0.997\u0026ndash;1.11)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.06\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGestational hypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.93\u003c/p\u003e\u003cp\u003e(0.86\u0026ndash;1.01)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.00\u003c/p\u003e\u003cp\u003e(0.93\u0026ndash;1.09)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.93\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePreeclampsia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.03\u003c/p\u003e\u003cp\u003e(0.95\u0026ndash;1.11)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.05\u003c/p\u003e\u003cp\u003e(0.98\u0026ndash;1.14)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eEclampsia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.31\u003c/p\u003e\u003cp\u003e(0.75\u0026ndash;2.29)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.16\u003c/p\u003e\u003cp\u003e(0.66\u0026ndash;2.05)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.61\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePreeclampsia and Eclampsia superimposed on preexisting hypertension\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.44\u003c/p\u003e\u003cp\u003e(1.27\u0026ndash;1.64)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.15\u003c/p\u003e\u003cp\u003e(0.99\u0026ndash;1.33)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.07\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eGestational diabetes mellitus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e10.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.75\u003c/p\u003e\u003cp\u003e(0.70\u0026ndash;0.79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.75\u003c/p\u003e\u003cp\u003e(0.70\u0026ndash;0.79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePlacenta previa\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.15\u003c/p\u003e\u003cp\u003e(0.97\u0026ndash;1.35)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.25\u003c/p\u003e\u003cp\u003e(1.06\u0026ndash;1.48)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.009\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDelivery outcomes\u003c/b\u003e \u003csup\u003e\u003cb\u003eb\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePreterm premature rupture of membranes\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.28\u003c/p\u003e\u003cp\u003e(1.13\u0026ndash;1.44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.30\u003c/p\u003e\u003cp\u003e(1.15\u0026ndash;1.47)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePreterm delivery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e8.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.45\u003c/p\u003e\u003cp\u003e(1.38\u0026ndash;1.52)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.37\u003c/p\u003e\u003cp\u003e(1.30.1.44)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAbruptio placenta\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.58\u003c/p\u003e\u003cp\u003e(1.39\u0026ndash;1.78)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.43\u003c/p\u003e\u003cp\u003e(1.26\u0026ndash;1.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eChorioamnionitis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.16\u003c/p\u003e\u003cp\u003e(1.03\u0026ndash;1.30)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.06\u003c/p\u003e\u003cp\u003e(0.94\u0026ndash;1.19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperative vaginal delivery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e4.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.97\u003c/p\u003e\u003cp\u003e(0.90\u0026ndash;1.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.90\u003c/p\u003e\u003cp\u003e(0.84\u0026ndash;0.97)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.004\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCesarean section\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e37.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e41.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.84\u003c/p\u003e\u003cp\u003e(0.82\u0026ndash;0.87)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.89\u003c/p\u003e\u003cp\u003e(0.86\u0026ndash;0.93)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSpontaneous vaginal delivery\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e57.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e53.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.19\u003c/p\u003e\u003cp\u003e(1.15\u0026ndash;1.23)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.12\u003c/p\u003e\u003cp\u003e(1.08\u0026ndash;1.17)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHysterectomy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.18\u003c/p\u003e\u003cp\u003e(0.80\u0026ndash;1.74)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.18\u003c/p\u003e\u003cp\u003e(0.78\u0026ndash;1.79)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.43\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePost-partum hemorrhage\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e3.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.98\u003c/p\u003e\u003cp\u003e(0.90\u0026ndash;1.08)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.95\u003c/p\u003e\u003cp\u003e(0.86\u0026ndash;1.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.24\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWound complications\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.18\u003c/p\u003e\u003cp\u003e(0.97\u0026ndash;1.45)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.30\u003c/p\u003e\u003cp\u003e(1.06\u0026ndash;1.59)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaternal death\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.72\u003c/p\u003e\u003cp\u003e(0.77\u0026ndash;9.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e2.14\u003c/p\u003e\u003cp\u003e(0.57\u0026ndash;8.03)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.26\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBlood transfusion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e1.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.53\u003c/p\u003e\u003cp\u003e(1.35\u0026ndash;1.73)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.35\u003c/p\u003e\u003cp\u003e(1.19\u0026ndash;1.54)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e\u003cp\u003e\u003cb\u003eOthers\u003c/b\u003e \u003csup\u003e\u003cb\u003ec\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMaternal infection\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e2.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.25\u003c/p\u003e\u003cp\u003e(1.13\u0026ndash;1.39)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.12\u003c/p\u003e\u003cp\u003e(1.01\u0026ndash;1.25)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.03\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDeep vein thrombosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.59\u003c/p\u003e\u003cp\u003e(0.96\u0026ndash;2.65)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.55\u003c/p\u003e\u003cp\u003e(0.92\u0026ndash;2.63)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePulmonary embolism\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e2.22\u003c/p\u003e\u003cp\u003e(1.16\u0026ndash;4.24)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.94\u003c/p\u003e\u003cp\u003e(0.99\u0026ndash;3.82)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.05\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eVenous thromboembolism\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.78\u003c/p\u003e\u003cp\u003e(1.19\u0026ndash;2.68)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.68\u003c/p\u003e\u003cp\u003e(1.10\u0026ndash;2.56)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.02\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eDisseminated intravascular coagulation\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.19\u003c/p\u003e\u003cp\u003e(0.89\u0026ndash;1.59)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.15\u003c/p\u003e\u003cp\u003e(0.85\u0026ndash;1.55)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.38\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003ea. Pregnancy outcome: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eb. Delivery outcomes: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003ec. Others: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eAbbreviations: OR, odds ratio; CI, confidence interval.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003eRegarding delivery outcomes, after controlling for the same confounding effects, women with hyperthyroidism were 1.3 times more likely to suffer preterm premature rupture of membranes, 1.37 times more likely to deliver prematurely, 1.43 times more likely to have a placental abruption, 1.12 times more likely to have a spontaneous vaginal delivery, 1.30 times more likely to have wound complications, 1.35 times more likely to require blood transfusions, 1.12 times more likely to have a maternal infection, and 1.68 times more likely to have a venous thromboembolism as compared to women with hypothyroidism. Women with hyperthyroidism were less likely to have an operative vaginal delivery and were less likely to undergo a caesarean section compared to women with hypothyroidism. Differences between outcomes were not statistically different between the two groups regarding rates of chorioamnionitis, hysterectomy, postpartum hemorrhage, maternal deaths, deep vein thrombosis, pulmonary embolism, and disseminated intravascular coagulation (p\u0026thinsp;\u0026ge;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003eThe crude and adjusted odds ratio for the association between neonatal outcomes and their prevalence in each group are outlined in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Women with hyperthyroidism were 1.47x more likely to have a baby that was small for gestation age, and 1.55 times more likely to have an intra-uterine fetal death. There was no difference in the prevalence of congenital anomalies between the two groups (p\u0026thinsp;\u0026ge;\u0026thinsp;0.05).\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eNeonatal outcomes a\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"6\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHyperthyroidism\u003c/p\u003e\u003cp\u003e(%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eHypothyroidism\u003c/p\u003e\u003cp\u003e(%)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eCrude OR\u003c/p\u003e\u003cp\u003e(95% CI)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eAdjusted OR\u003c/p\u003e\u003cp\u003e(95% CI)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eAdjusted\u003c/p\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSmall for gestational age infant\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e4.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.71\u003c/p\u003e\u003cp\u003e(1.58\u0026ndash;1.85)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.47\u003c/p\u003e\u003cp\u003e(1.35\u0026ndash;1.59)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eIntrauterine fetal death\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e1.81\u003c/p\u003e\u003cp\u003e(1.49\u0026ndash;2.19)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e1.55\u003c/p\u003e\u003cp\u003e(1.27\u0026ndash;1.89)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCongenital Anomalies\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e0.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.80\u003c/p\u003e\u003cp\u003e(0.66\u0026ndash;0.98)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.85\u003c/p\u003e\u003cp\u003e(0.70\u0026ndash;1.04)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e0.11\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003ea. Fetal outcomes: adjusted for age, race, plan type, income, obesity, chronic hypertension, illicit drug use, previous cesarean section, tobacco smoking during pregnancy, pregestational diabetes mellitus, pregnancy-induced hypertension, gestational diabetes mellitus, and placenta previa.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"6\"\u003eAbbreviations: OR, odds ratio; CI, confidence interval.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eOur study was based on data from a large American population and includes 16,984 pregnancies with a documented diagnosis of hyperthyroidism and 184,655 pregnancies with a documented diagnosis of hypothyroidism. Cases of pregnancies with a diagnosis of hyperthyroidism were compared to pregnancies with a diagnosis of hypothyroidism, who acted as the control group. Maternal characteristics, including demographics and pre-pregnancy comorbidities, differed between the two groups, which was accounted for in the adjusted analysis. Participants with hyperthyroidism had a small but significative increased risk of certain pregnancy and delivery outcomes when compared to participants with hypothyroidism. Numerous studies have explored thyroid dysfunction during pregnancy and its association with adverse outcomes relative to the general population. Our study is novel, as it compares the risks of hyperthyroidism versus hypothyroidism during pregnancy, thereby providing a new perspective to the existing literature. These findings will provide additional insight to the clinical judgment of practitioners caring for thyroid disorders in pregnancy.\u003c/p\u003e\n\u003ch3\u003ePregnancy outcomes\u003c/h3\u003e\n\u003cp\u003eRegarding pregnancy outcomes, the American Thyroid Association, in its guidelines during pregnancy, mentions an increased risk of hypertensive disorders of pregnancy for both women with hyperthyroidism and hypothyroidism [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. We reported no significant difference between the two groups regarding rates of pregnancy-induced hypertension, gestational hypertension, preeclampsia, and eclampsia.\u003c/p\u003e\u003cp\u003eIn Lancet reviews, gestational diabetes mellitus was associated with hypothyroidism during pregnancy [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], while it was not noted in the context of hyperthyroidism during pregnancy [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Our study confirmed this finding and demonstrated that women with hypothyroidism were more likely to have gestational diabetes mellitus compared to women with hyperthyroidism. Our study supports the established literature that the studied thyroid disorders are associated with hypertensive disorders of pregnancy to a similar magnitude, and that hypothyroidism has greater risks of gestational diabetes mellitus than hyperthyroidism.\u003c/p\u003e\n\u003ch3\u003eDelivery outcomes\u003c/h3\u003e\n\u003cp\u003eThyroid hormone is important for adequate trophoblast function and migration [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], and proper placental implantation [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Abnormal placentation has been suggested as a cause of idiopathic preterm birth [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], and other pregnancy complications in thyroid disorders [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Partially due to the mechanisms described above, delivery complications are well described in women with thyroid dysfunction, but the relative risk of hyper- versus hypothyroidism is seldom reported. In a prospective population-based cohort study, placental abruption was reported in a group of participants with iatrogenic hypothyroidism [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In our study population, the increased risk of placental abruption was seen in women with hyperthyroidism, as compared to women with hypothyroidism. In a meta-analysis including 14 cohort studies and 1 case-control for a total of 1,523,704 participants, preterm birth was more frequent in children born to mothers with a diagnosis of thyroid dysfunction compared to the general population. In this meta-analysis, the adjusted risk was slightly greater in participants with a diagnosis of hyperthyroidism (OR 1.24) than in participants with a diagnosis of hypothyroidism (OR 1.19) [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. This is concordant with our findings, where the risk of preterm birth was 1.4-fold higher in participants with hyperthyroidism when compared to hypothyroidism and higher than the magnitude reported in the meta-analysis. In a Chinese population-based cohort study of 184,611 women, high TSH levels, between 4.29 and 10.00 IU/L, hypothyroidism was associated with an increased risk of cesarean delivery and operative delivery when compared to the general population [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Participants with low TSH were not evaluated [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Similarly in our study, participants with hypothyroidism were more likely to undergo cesarean section or operative vaginal delivery compared to hyperthyroid participants, who were more likely to undergo spontaneous vaginal delivery. One prospective population-based cohort study reported ICU admission as a delivery-associated complication of primary hypothyroidism and hyperthyroidism [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The causes of admission were not listed. In our study, outcomes related to maternal morbidity such as chorioamnionitis, hysterectomy, postpartum hemorrhage, venous thromboembolism, disseminated intra coagulation and maternal death were comparable between the two groups. Risks were slightly higher among the hyperthyroid group for wound complications, blood transfusions, and maternal infections. Many of these risks could lead to ICU admission, which was not coded for in the database.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eNeonatal outcomes\u003c/h2\u003e\u003cp\u003eIn a Danish population-based study comparing birth weight of infants born to mothers with thyroid dysfunction, maternal hypothyroidism was associated with infants born large for gestational age, while hyperthyroidism was associated with infants born small for gestational age [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. We obtained similar findings, as infants born to hyperthyroid mothers were more likely to be small for gestational age when compared to those born to hypothyroid mothers. Both hypo- and hyperthyroidism have been described to be associated with an increased risk of stillbirth compared to the general population [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. A Turkish cross-sectional study of 1519 participants reported increased risks of late fetal losses in hypothyroid women [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. In our study, the risk of intrauterine fetal death was increased in the hyperthyroid group than in the hypothyroid group. Studies report a small but significant increase in congenital anomalies among infants born to hypothyroid mothers [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. A recent meta-analysis suggested that both overt hyperthyroidism and antithyroid drugs can increase the risk of congenital anomalies [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Our study identified no difference in the rates of congenital anomalies between infants born to hypo- and hyperthyroid mothers.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eStrengths and limitations\u003c/h3\u003e\n\u003cp\u003eOur study has several limitations, the most important being that it was a retrospective analysis with unavailable TSH levels and other laboratory values. We could not verify the diagnosis of hyperthyroidism or hypothyroidism and whether they were posed in a consistent manner, or if diagnoses varied based on the diagnosing physician. Transient gestational thyrotoxicosis secondary to beta-hCG further complexifies the diagnosis of hyperthyroidism[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. As this presentation resolves during the first trimester, it should not lead to a misclassification of healthy subjects as hyperthyroid patients at the time of the birth of their child. It is unlikely that normal subjects were included in the analysis, however, diagnostic heterogeneity likely existed. In 2011, which is included in our study period, the American Thyroid Association (ATA) first published guidelines on the diagnosis and management of thyroid disease in pregnancy, which were updated in 2017[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Updated guidelines likely have changed diagnosis and management practices, but as this is a population-based study, the estimated risks likely represent practices as they evolve with guidelines. It should also be noted that all women diagnosed as hypothyroid prior to 2017 would also have been included in the diagnoses with the revised guidelines. As laboratory values are unavailable, we are unable to reclassify participants according to current guidelines. Further studies beyond the scope of this article will be required to assess the impact of evolving guidelines on practice and adverse pregnancy outcomes.\u003c/p\u003e\u003cp\u003eAnother limitation is that we were unable to ascertain medication use and compliance during pregnancy. This prevents us from studying the effects of medication type and compliance on the outcomes. Nonetheless, as this is a population-based study, we can estimate that the participants reflect the use and compliance of medications in the general population. We could not include the data from 2015 and onwards dye to alterations in the ICD coding system which are incomparable with ICD-9 codes.\u003c/p\u003e\u003cp\u003eThe odds ratios we estimated are of small magnitude. This informs us that the increased risks generally associated with hyperthyroidism when compared to hypothyroidism are only mildly elevated.\u003c/p\u003e\u003cp\u003eStrengths of our study include its magnitude, with more than 200,000 cases studied over the span of 10 years. The power of our study allows us to control for potential confounders. The findings are in alignment with the published literature on thyroid disorders during pregnancy and provide an interesting insight into the comparison between hypo- and hyperthyroidism. This is likely the first population-based study to perform such a comparison.\u003c/p\u003e\u003cp\u003eIn conclusion, our large population-based study from the American Healthcare Cost and Utilization Project-Nationwide Inpatient Sample (HCUP-NIS) database provides novel and interesting insight into thyroid disorders in pregnancy, with an overall small but significant increase in the risk of adverse outcomes for participants with hyperthyroidism when compared to hypothyroidism. These results provide insight into the understanding of thyroid disorders during pregnancy.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003ch2\u003eCompeting Interests\u003c/h2\u003e\u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e\u003c/p\u003e\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003cp\u003eThis study used exclusively publicly accessible, anonymized data; therefore, according to the Tri-Council Policy Statement, intuitional review board approval was not required. The data that support the findings of this study are available in NIS Database Documentation at \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp\u003c/span\u003e\u003cspan address=\"https://hcup-us.ahrq.gov/db/nation/nis/nisdbdocumentation.jsp\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e and are available to the public.\u003c/p\u003e\u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e\u003cp\u003eWe have no sources of funding to declare.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e\u003cp\u003eNone.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eKorevaar TIM, Medici M, Visser TJ, Peeters RP (2017) Thyroid disease in pregnancy: new insights in diagnosis and clinical management. 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Clin Biochem. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.clinbiochem.2008.05.002\u003c/span\u003e\u003cspan address=\"10.1016/j.clinbiochem.2008.05.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eTurunen S, V\u0026auml;\u0026auml;r\u0026auml;sm\u0026auml;ki M, M\u0026auml;nnist\u0026ouml; T, Hartikainen AL, Lahesmaa-Korpinen AM, Gissler M et al (2019) Pregnancy and Perinatal Outcome Among Hypothyroid Mothers: A Population-Based Cohort Study. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1089/thy.2018.0311\u003c/span\u003e\u003cspan address=\"10.1089/thy.2018.0311\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Thyroid\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eWikner BN, Sparre LS, Stiller CO, K\u0026auml;ll\u0026eacute;n B, Asker C (2008) Maternal use of thyroid hormones in pregnancy and neonatal outcome. Acta Obstet Gynecol Scand. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/00016340802075103\u003c/span\u003e\u003cspan address=\"10.1080/00016340802075103\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMorales DR, Fonkwen L, Nordeng HME (2021) Antithyroid drug use during pregnancy and the risk of birth defects in offspring: systematic review and meta-analysis of observational studies with methodological considerations. Br J Clin Pharmacol. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/bcp.14805\u003c/span\u003e\u003cspan address=\"10.1111/bcp.14805\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"hormones","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"HORM","sideBox":"Learn more about [Hormones](https://www.springer.com/journal/42000)","snPcode":"42000","submissionUrl":"https://www.editorialmanager.com/horm/default2.aspx","title":"Hormones","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Hypothyroidism, Hyperthyroidism, Pregnancy outcomes, Delivery outcomes, Neonatal outcomes","lastPublishedDoi":"10.21203/rs.3.rs-8148224/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8148224/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e\u003cp\u003eBoth hypothyroidism and hyperthyroidism have been linked with unfavourable pregnancy outcomes. Our goal was to better understand the implications of these disease processes on pregnancy and compare outcomes in women with hyperthyroidism versus hypothyroidism.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e\u003cp\u003eWe performed a retrospective population-based cohort study using the Health Care Cost and Utilization Project-Nationwide Inpatient Sample. We included all deliveries with maternal hyperthyroidism or hypothyroidism between 2004\u0026ndash;2014. We compared pregnancy, delivery, and neonatal outcomes between participants with hyperthyroidism and hypothyroidism. Multivariate logistic regression analysis was used to calculate adjusted-odds-ratios (aOR) and 95% confidence internals (95%CI).\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e\u003cp\u003eWe studied 16,984 pregnancies with hyperthyroidism, and 184,655 with hypothyroidism. Participants with hyperthyroidism were less likely to have gestational diabetes mellitus (aOR:0.75;95%CI:0.70\u0026ndash;0.79), operative vaginal delivery (aOR:0.90;95%CI:0.84\u0026ndash;0.97), and cesarean section (aOR:0.89;95%CI:0.86\u0026ndash;0.93) when compared to participants with hypothyroidism. They were more likely to have preterm premature rupture of membranes (aOR:1.30;95%CI:1.15\u0026ndash;1.47), preterm delivery (aOR:1.37;95%CI:1.30\u0026ndash;1.44), abruptio placenta (aOR:1.43;95%CI:1.26\u0026ndash;1.63), wound complications (aOR:1.30;95%CI:1.06\u0026ndash;1.59) and blood transfusions (aOR:1.35;95%CI:1.19\u0026ndash;1.54). Infants born to hyperthyroid mothers were likelier to be small for gestational age (aOR:1.47;95%CI:1.35\u0026ndash;1.59) compared to infants born to hypothyroid mothers. There were no differences for gestational hypertensive disorders, chorioamnionitis, hysterectomy, postpartum hemorrhage, maternal death, and congenital anomalies (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eHyperthyroidism was associated with increased risk of pregnancy outcomes compared to hypothyroidism, with a few exceptions, particularly rates of gestational diabetes and caesarean section which were decreased in this group. Our study is novel as it compares the risks of hyperthyroidism versus hypothyroidism during pregnancy, thereby providing a new perspective to the existing literature.\u003c/p\u003e","manuscriptTitle":"Comparing the pregnancy risks of hyperthyroidism and hypothyroidism: A study of an American population database with more than 200,000 cases","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-01 11:13:10","doi":"10.21203/rs.3.rs-8148224/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revisions","date":"2025-12-15T03:54:26+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-11-25T13:44:48+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-11-25T12:54:23+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Hormones","date":"2025-11-25T08:55:09+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-20T01:55:22+00:00","index":"","fulltext":""},{"type":"submitted","content":"Hormones","date":"2025-11-18T13:10:44+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"hormones","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"HORM","sideBox":"Learn more about [Hormones](https://www.springer.com/journal/42000)","snPcode":"42000","submissionUrl":"https://www.editorialmanager.com/horm/default2.aspx","title":"Hormones","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"0636aa64-cce0-4593-a00c-b65a7e05c41e","owner":[],"postedDate":"December 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2025-12-15T08:55:06+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-01 11:13:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8148224","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8148224","identity":"rs-8148224","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}