Association between preconception maternal beverage intake and in vitro fertilization outcomes.

Up to 10% of reproductive aged couples suffer from infertility ( 1 ) with more than 600,000 IVF cycles performed in Europe in 2011 ( 2 ) and more than 140,000 IVF cycles performed in the USA in 2014 ( www.sartcorsonline.com ). Despite the relative increase in pregnancy rates with time, overall success rates of IVF remain relatively low. To date, the best characterized predictors of IVF success are unmodifiable (i.e., patient age), hence the need to investigate potentially modifiable factors, one example of which is type of beverages consumed ( 3 – 5 ). Among the most popular beverages consumed by reproductive aged women are caffeinated drinks, sugared sodas, and diet sodas. Caffeine is a stimulant of the central nervous system ( 6 ). While increased caffeine consumption is associated with lower estrogen levels in the luteal phase ( 7 – 9 ), the effects of caffeinated beverages on fecundity are still inconsistent ( 6 , 10 – 13 ). Intake of sugared soda has been linked to weight gain as well as a rapid increase in circulating insulin and insulin-like growth factor 1 (IGF-1) levels and insulin resistance due to their high glycemic content ( 14 ). Moreover, soda drinkers are potentially exposed to higher levels of endocrine disruptors chemicals such as bisphenol A, which migrate from the coating of soda cans into the liquid ( 15 ). Most studies to date have evaluated the effects of caffeine, sugared sodas and diet beverages either on time to conception or risk of fetal loss and the results are still conflicting ( 16 – 20 ). However, the effects of these beverages on intermediate IVF cycle outcomes (i.e., number of oocytes retrieved, oocyte maturation, fertilization and day 3 embryo quality) as well as clinical IVF outcomes (positive beta-hCG, clinical pregnancy rates, spontaneous abortions and live births) have been less well studied ( 21 – 23 ). In the most recent study on this topic, Abadia and colleagues found no association between low to moderate caffeine intake (<200mg/day) and IVF outcomes in a prospective cohort on infertile women in the USA ( 24 ). They also found no associations with any of the specific caffeinate beverages. However, due to the low soda consumption in that cohort, the study was unable to assess whether consumption of these beverages is related with ART outcomes. The aim of the current study was to evaluate the associations between preconception drinking habits of women with fresh IVF cycle outcomes in a prospective cohort of women from outside the USA consuming much higher levels of caffeine (mainly instant coffee) and sodas (both full calorie and diet).

From January 2014 through August 2016, 359 women undergoing a fresh IVF cycle at a tertiary university affiliated hospital were recruited into a study on environmental exposures and fertility. Cryopreserved cycles were excluded from our analysis. The study was approved by our local IRB and all patients signed informed consents. Participants were enrolled during ovarian stimulation and followed through one fresh IVF cycle. For the analysis of intermediate IVF outcomes, exclusion criteria included women with missing embryology (n=3) or exposure (n=2) information, women who froze their oocytes (n=11), women using egg donors (n=1), and women missing information on oocyte retrieval (n=2). Thus, the final dataset consisted of 340 women. For the analysis of clinical IVF outcomes, we further excluded one woman who was lost to follow-up after identification of a clinical pregnancy, bringing the final analytic sample to 339 women. Women reported their usual intake of caffeinated and non-caffeinated beverages on the first day of stimulation and/or on the day of oocyte retrieval. The questionnaire specifically asked women, “Do you drink any of the following 14 beverages: filtered coffee, instant coffee, boiled black coffee, mud coffee, decaffeinated coffee, cappuccino, espresso, caffeinated tea, herbal tea, chocolate drinks, caffeinated soda, caffeinated diet sodas, non-caffeinated diet sodas, and energy drinks and, if so, in what quantity (in cups)”. Women were also provided with information on converting common serving sizes to cups (e.g. 1 mug = 2 cups). Total caffeine intake was estimated by summing the caffeine content for each specific beverage multiplied by their frequency of intake. We assumed the following caffeine concentrations for each caffeinated beverage: filtered coffee, 95 mg/cup; instant coffee, 63 mg/cup; boiled black and mud coffee, 115 mg/cup; decaffeinated coffee, 2 mg/cup; cappuccino, 64 mg/cup; espresso, 64 mg/shot; caffeinated tea, 26 mg/cup; chocolate drinks, 5 mg/cup; caffeinated sodas, 16 mg/cup; and energy drinks, 111 mg/cup. Height and weight, measured at the start of the IVF cycle by a trained nurse, were used to calculate body mass index (BMI) (kg/m 2 ). A woman’s age, smoking status, number of previous pregnancies and deliveries, duration of infertility, and IVF attempt number were abstracted from patients’ medical records. On the same questionnaire as the beverages, women also provided information on their country/region of birth, years of education, smoking history, and field of employment. Patients were treated with controlled ovarian stimulation using one of three protocols (GnRH antagonist, GnRH agonist suppressive protocol or GnRH agonist flare-up protocol) as clinically indicated. Patients were monitored during gonadotropin stimulation for serum estradiol, follicle size measurements and counts, and endometrial thickness through 2 days before oocyte retrieval. Human chorionic gonadotropin (hCG) was administered approximately 36 hours before the scheduled oocyte retrieval procedure to induce oocyte maturation. Women received conventional insemination or intracytoplasmic sperm injection (ICSI) as clinically indicated. Embryologists classified oocytes as germinal vesicle, metaphase I, metaphase II (MII) or degenerated. Embryologists determined fertilization 16 to 18 hours after insemination as the number of oocytes with two pronuclei. The resulting embryos were assessed for cell number, symmetry and fragmentation ( 25 ). Top quality embryos were considered to be embryos with 7–8 cells on day 3 (or in cases of day 2 transfer, 4 cells) and 25 mIU/mL typically measured 14 days after oocyte retrieval. Embryos were scheduled for transfer on day 3 in non-PGD patients. In cases that day 3 was a holiday, transfers were performed on day 2 (n=12 cycles). For PGD patients, embryos were biopsied on day 3 and transferred on day 4. Clinical pregnancy was defined as the presence of an intrauterine gestational sac and fetal heartbeat confirmed by ultrasound by 7 weeks of gestation, and live birth as the delivery of a live neonate on or after 24 weeks gestation. All clinical information was abstracted from medical records. Women were stratified into quartiles of total caffeine intake and categories of beverage consumption based on the distribution of consumption in the population. Descriptive statistics, calculated for demographic and reproductive characteristics in the entire cohort and by quartile of total caffeine intake, were presented as mean (standard deviation) or number of women (%). For continuous and categorical variables, ANOVA and chi-square tests were used, respectively, to test for associations across categories of total caffeine intake. To evaluate the association between caffeine and beverage intake and number of total oocytes, mature oocytes, fertilized oocytes, and top quality embryos (all count data), we used a multivariable Poisson regression with log link. Adjusted marginal mean counts for each quartile or category were obtained. For the clinical outcomes, we used a multivariable logistic regression model to derive the adjusted proportion of initiated cycles resulting in implantation, clinical pregnancy, and live birth for each quartile or category. Risk of pregnancy loss was evaluated among women with an implantation and was defined as any loss of pregnancy prior to live birth. To test associations between caffeine and beverage intake and pregnancy loss, we used a Poisson regression with log link and present results as risk ratios (95% CIs). Tests for trend were conducted across quartiles or categories using the median level of intake in each category as a continuous variable in the regression models. Confounding was evaluated using prior knowledge and descriptive statistics from our cohort. Variables retained in the final multivariable models were age, BMI, smoking status, and country of origin. Specific beverages also were further adjusted for coffee, caffeinated tea, herbal tea, sugared soda, and energy drink intakes. To test for potential effect modification by PGD, we included a cross-product term in the final multivariable model. All analyses were conducted using SAS Software package 9.4 (Cary NC).

Between January 2014 and August 2016, 340 women who underwent ovarian stimulation for a fresh IVF cycle completed questionnaires on their recent consumption of coffee, tea, hot chocolate, soda, and energy drinks. The women were 31.5 ± 4.0 years and had a BMI of 23.4 ± 4.5 kg/m 2 ( Table 1 ). Their primary reason for undergoing IVF was preimplantation genetic diagnosis for autosomal recessive disorders (n=129 women, 37.9%) followed by male factor infertility (33.8%), unexplained infertility (16.8%), and known female factors (i.e., anovulation or endometriosis) (11.5%). The majority (62.4%) of women was undergoing their first IVF cycle, 20.9% were undergoing their second IVF cycle, and 16.8% were undergoing their third IVF cycle. There were no differences regarding the number of embryos transferred, the number of top quality embryo transferred and the day of transfer across the quartiles of caffeine intake. The mean ± SD caffeine intake of women in our cohort was 163.5 ± 125.3 mg/day which corresponds to about 2.5 cups of instant coffee per day. Women with higher caffeine intake were, on average, slightly older and more likely to be current smokers ( Table 1 ); all other demographic and reproductive characteristics were similar across quartiles of caffeine intake. There were no associations between total caffeine intake and number of total or mature oocytes, fertilized oocytes, or top quality embryos ( Table 2 ). Similarly, total coffee intake was not associated with these outcomes. Higher consumption of instant coffee was associated with a slightly lower number of fertilized oocytes. However, none of the other coffee beverages were related to this or other oocyte or embryo outcomes. On the other hand, women with higher caffeinated tea intake had a lower number of total (P-trend=0.001) and mature oocytes (P-trend=0.003) and a lower number of fertilized oocytes (P-trend=0.05). In contrast, herbal tea intake, was associated with higher total and mature oocyte yield (P-trend=0.001 and 0.02, respectively). Intake of sugared soda, but not of diet soda, was associated with lower total and mature oocytes, fertilized oocytes, and top quality embryos. Women who consumed sugared soda had, on average, 1.1 fewer oocytes retrieved, 1.2 fewer mature oocytes retrieved, and 0.6 fewer fertilized oocytes compared to women who did not consume sugared soda (p for trend=0.002, <0.001, and 0.01, respectively). Similarly, inverse associations were seen for these same outcomes comparing energy drink consumers to non-consumers (p-value for comparisons=<0.001, <0.001. and 0.005, respectively). Among the 339 women who were included in analysis of clinical outcomes, 283 (83.5%) had an embryo transfer, 116 (34.2%) had positive β-hCG 14 days after embryo transfer, 102 (30.1%) had a clinical pregnancy, and 83 (24.5%) had a live birth. Total caffeine intake was not associated with probability of positive β-hCG, clinical pregnancy, or live birth following IVF ( Table 3 ). Of all the beverages examined, only sugared soda intake was related to clinical outcomes. Higher intake of sugared sodas was inversely associated with clinical pregnancy (P-trend=0.01) and live birth (P-trend=0.01). Specifically, compared to women who reported no sugared soda intake (0 cups/day), the adjusted difference in percent of cycles resulting in live birth for women consuming 0.1–1 cups/day and >1 cup/day were −12% and −16%, respectively (p-trend=0.01). When the analysis was restricted to only women who underwent embryo transfer, this association strengthened ( Supplemental Table 1 ). The adjusted differences in percent of transfers resulting in live birth for women consuming s0.1–1 cups/day and >1 cup/day compared to non-consumers were −15% and −19%, respectively (p-trend=0.01). Among women with implantation, the risk of pregnancy loss prior to delivery was 3.51 (95% CI 1.46, 8.45) times higher among women consuming >1 cup/day of sugared soda compared to women consuming no sugared soda (P-trend=0.02). There was no evidence of effect modification by PGD for the association between caffeine and sugared soda and live birth (p-value for interaction=0.43 and 0.85, respectively).

In our prospective cohort of women undergoing IVF we found that higher preconception intake of sugared sodas was associated with a lower number of total and mature oocytes retrieved, a lower number of fertilized oocytes as well as a lower proportion of cycles resulting in clinical pregnancy and live birth. Intake of caffeinated tea and energy drinks was also associated with poorer oocyte and embryo outcomes but these associations did not translate into poorer clinical outcomes. Contrary to our hypothesis, however, intake of caffeine, coffee, specific caffeinated beverages, or diet sodas, failed to show consistent associations with any of the outcomes examined. Regarding our initial hypotheses that caffeine and/or the increased glycemic impact of sugar in beverages might alter IVF outcomes, the one most supported by our data is the second one pertaining to sugar. This proposed mechanism not only fits with the sugar soda findings, but also explains the results regarding energy drinks, which often contain high levels of either sucrose or high-fructose corn syrup. Moreover, it is possible that a high proportion of women add sugar to their caffeinated tea which might explain why we also found a similar inverse association with this beverage and intermediate IVF outcomes. Consumption of sugared soda has been linked to abnormal markers of glycemic control such as insulin resistance, metabolic syndrome and type 2 diabetes ( 26 – 29 ). Insulin resistance is a situation in which the responsiveness of the body to the hormone insulin is diminished, resulting in metabolic dysregulation ( 30 , 31 ). Insulin resistance can alter the maternal metabolic environment and follicular fluid microenvironment, leading to lower quality oocytes and embryos ( 9 , 11 , 32 ). In mice, this condition leads to altered mitochondrial function and abnormal spindle formation ( 33 ). Interestingly, another marker of abnormal glycemic control, glycosylated hemoglobin (HbA1C), which increases in diabetes, was previously reported to be associated with reduced fertility ( 34 ). We found that the proportion of cycles resulting in clinical pregnancy and live birth was lower among women who consumed higher levels of sugared sodas compared with those who drank lower levels of these beverages. Although to the best of our knowledge, the only other study that has investigated the association between female intake of sugared sodas IVF outcomes found no association between usual intake of soda in the year prior to infertility treatment and probability of live birth ( 24 ). However, this study did not distinguish between diet and sugared soda and was limited by a low number of high soda consumers (only 8.3% reported consuming >=1 one serving of any type of soda while in our study 27.9% of women reported consuming >=1 one cup of any type of soda). This previous study also only focused on sub-fertile women undergoing ART for infertility treatment as compared to our cohort which also included women undergoing ART for PGD. Taken together, these differences in study population could help explain some of our seemingly discrepant findings. In contrast, and more in line with our current findings, a previous study among women conceiving spontaneously showed that women who consumed high levels of sugar sweetened beverages had decreased fecundity. Specifically, among 3628 women planning a pregnancy in Denmark the adjusted fecundability ratios were 0.89 (0.80–0.98), 0.85 (0.71–1.02), 0.84 (0.57–1.25), and 0.48 (0.21–1.13) for < 1, 1, 2, and 3+ servings per day, respectively, compared with none ( 16 ). This inverse association with fecundity, however, was not confirmed in a more recent prospective study among 2135 North American pregnancy planners ( 11 ). Moreover, in this same cohort of women, there was no link between pre-pregnancy soda consumption and pregnancy loss ( 35 ). In contrast with our hypothesis, we failed to find an association between caffeine consumption and number of total, mature, or fertilized oocytes or embryo quality. Also, pre-conception caffeine intake was not associated with implantation, clinical pregnancy, or live birth. Our results are in line with a previous study of 221 women undergoing IVF, in which no associations were observed for between recent caffeine intake and IVF outcomes ( 23 ). A lack of association between current consumption of caffeine and number of oocytes retrieved, fertilization rate, implantation rate, or live birth rate was also reported by Choi et al., who evaluated 2,474 women undergoing 4,716 IVF treatment cycles from 1994 to 2003 ( 21 , 22 ). A third study among 619 women undergoing IVF also found no significant associations between current caffeine intake and pregnancy rate, despite having a median caffeine intake of 455.8 mg/day ( 21 ). Finally, the most recent study on caffeine intake and IVF outcomes (n=300 women, 493 IVF cycles) found no association between usual caffeine intake over the previous year and intermediate or clinical outcomes of IVF ( 24 ). Our study was subject to some limitations. Although women reported their intake of specific beverages (in cups), there is still likely error in their self-report as information on serving size and amount consumed was limited. Furthermore, the brewing method for the specific coffee types was not collected which could impact the quantity of caffeine in a given serving size. However, misclassification of beverage intake is unlikely to be linked with IVF outcome given the prospective nature of our study and would therefore tend to attenuate our associations towards the null. We also lacked information regarding the beverage habits during the pregnancy and it is possible that patients change their drinking beverage habits through pregnancy, especially by decreasing their caffeine and diet soda consumption. Beverage consumption could also be correlated with other diet and lifestyle factors as well as dietary consumption that were not assessed and that may confound the relation with fertility. Thus, we cannot exclude the possibility that the lack of association seen in our data is an artifact produced by unmeasured factors. Finally, given the sample size of our study, our results cannot rule out modest effect sizes, which we were underpowered to detect. Despite the above limitations, our analysis had several important strengths. First, collection of prospective data from relatively large number of women undergoing IVF enables us to get accurate data regarding their usual drinking habits before oocyte retrieval. Second, in order to generalize our results, we included also fertile women, undergoing IVF for preimplantation genetic diagnosis. Moreover, our cohort included a wide range of caffeine intake, which allowed us to examine more relevant levels of exposure given the high intake of caffeine by reproductive aged women in many countries ( 36 , 37 ). Last, all patients underwent their IVF treatment in the same program, enabling standardization of the laboratory conditions and limiting possible inter-observer variations. In conclusion, pre-pregnancy consumption of sugared sodas seems to have the most detrimental impact on IVF outcomes compared to other commonly consumed beverages. Given our findings, it is possible that sugar, rather than the caffeine, is a stronger reproductive toxicant. Although we failed to find an association between caffeine consumption and IVF outcomes, these results should to be interpreted with caution and deserve further evaluation, including measurement of urinary caffeine metabolites to assess the accurate level of exposure.

Associations between beverage intake and clinical outcomes of in vitro fertilization per embryo transfer (n=283 women/embryo transfer cycles).