Use of heated tobacco products may be associated with hypertensive disorders of pregnancy and low birth weight in Japan: An analysis of the JACSIS study

34

Little is known about heated tobacco product (HTP) use in pregnant women 35 and associated maternal and neonatal risks for hypertensive disorders of pregnancy (HDP) 36 and low birth weight (LBW). Thus, this study aimed to assess the status of HTP use among 37 pregnant women in Japan and explore the risk of HDP and LBW associated with HTP use. 38

Using data from the Japan “COVID-19 and Society” Internet Survey (JACSIS) 39 study, a web-based nationwide survey, we investigated 558 post-delivery and 365 currently 40 pregnant women in October 2020. We assessed the prevalence of ever HTP smokers (defined 41 as ever experiencing HTP use) in post-delivery and currently pregnant women. Among post-42 delivery women, we collected the information regarding HDP and LBW based on their 43 Maternal and Child Health Handbooks (maternal and newborn records). In the multivariable 44 regression analysis, we estimated the adjusted odds ratios (ORs) and 95% confidence 45 intervals (CIs) of ever HTP smokers for HDP and LBW compared with those of never HTP 46 smokers using logistic regression. A stratified analysis with respect to combustible cigarette 47 smoking (never/ever) was also performed. 48

The prevalence of ever HTP use were 11.7% and 12.6% in post-delivery and 49 currently pregnant women, respectively. Among post-delivery women, ever HTP smokers 50 had higher HDP incidence (13.8% vs. 6.5%, P=0.03), with an OR of 2.78 (95% CI 0.84–51 9.15) and higher LBW incidence (18.5% versus 8.9%, P=0.02), with an elevated OR of 2.08 52 (95% CI 0.80–5.39). A similar tendency was observed among never and ever combustible 53 cigarette smokers. 54

In Japan, the incidence of HTP use has exceeded 10% among pregnant women, 55 and HTP smoking may be associated with increased maternal and neonatal risks. School-56 based tobacco prevention and cessation programs should be conducted regardless of product 57 types to prevent life-threatening perinatal complications and deaths. 58 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 4

heated tobacco products, hypertensive disorders of pregnancy, COVID-19, 59 smoking, preconception 60 61 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 5

62 The widespread use of heated tobacco products (HTPs) is an emerging public health 63 concern.[1] Since the initial marketing of HTPs in 2014, the prevalence of HTP use has 64 increased in Japan, exceeding 15% in the young population aged 20–39 years in 2019,[2] and 65 this incidence was maintained over 15% during the coronavirus disease (COVID-19) 66 pandemic in 2020.[3] 67 Although the impression of HTPs as a healthy alternative to combustible cigarettes is 68 promoted by the advertising of HTPs (e.g., reduced harmfulness and a smoke-free image),[4] 69 HTP-related unfavorable health outcomes, including acute respiratory and cardiovascular 70 risks, are likely to occur.[5, 6] However, little is known about HTP use and associated 71 maternal and neonatal risks in pregnant women, including hypertensive disorders of 72 pregnancy (HDP) and low birth weight (LBW).[7, 8] Although some controversial 73 associations have been reported for HDP with respect to combustible cigarettes,[9] this type 74 of cigarettes increases various maternal and neonatal risks in Japan.[10, 11] Therefore, we 75 hypothesized that HTP use is associated with HDP and LBW, regardless of combustible 76 cigarette smoking. 77 This study aimed to assess the status of HTP use among pregnant women in Japan and 78 explore the risk of HDP and LBW associated with the use of HTP by analyzing data from a 79 nationwide web-based survey in Japan that contained pregnancy-related information and data 80 related to behavioral factors (e.g., HTP use and combustible cigarette smoking), and social 81 background. 82 83

84 Data setting 85 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 6 This cross-sectional internet-based study is part of the Japan COVID-19 and Society Internet 86 Survey (JACSIS) study. The JACSIS study comprises three surveys in the following three 87 target populations: (a) young people and adults aged 15–79 years, (b) currently pregnant and 88 post-delivery women, and (c) adults living in a single-parent household. The study samples 89 for each survey were retrieved from the pooled panels of an internet research agency 90 (Rakuten Insight, Inc., which had approximately 2.2 million panelists in 2019).[12] We used 91 data from currently pregnant and post-delivery women, which were collected in October 92 2020. 93 The internet research agency identified 21,896 eligible women, randomly selected 4373 94 women who gave birth after October 2019 or who were expected to give birth by March 95 2021, and distributed the questionnaire comprising 61 questions to the selected women 96 through a designated website. Next, we collected data from 1000 women (response rate, 97 22.9%) stratified by delivery date as follows: (a) 600 post-delivery women who delivered 98 during October 2019–March 2020 (n=200), April–May 2020 (n=200), and June–October 99 2020 (n=200) and (b) 400 currently pregnant women who were expected to deliver during 100 October 2020–March 2021. Among 1000 study participants, we excluded 77 who provided 101 irrelevant or conflicting information (45 post-delivery and 32 currently pregnant women) as 102 done in previous studies of the same research agency,[13] yielding a total of 923 study 103 participants for the analysis (558 post-delivery and 365 currently pregnant women). Informed 104 consent was obtained electronically, and the Institutional Review Board of the Osaka 105 International Cancer Institute approved the study (Protocol Number 20084). 106 107 Definition of HDP and LBW 108 Data on HDP and LBW were extracted from the web-based self-reported questionnaires. We 109 defined the incidence of HDP based on whether the study participants had been diagnosed as 110 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 7 having HDP or preeclampsia during pregnancy. The criteria for HDP diagnosis in Japan were 111 derived from the criteria of the American College of Obstetricians and Gynecologists (i.e., 112 systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg after the 20th 113 week of gestation).[14] We defined the incidence of LBW on the basis of the diagnosis of 114 LBW (birth weight <2500 g). 115 All participants were asked to provide information from their Maternal and Child 116 Health Handbooks. In brief, as previously described,[15, 16] the Maternal and Child Health 117 Handbooks are well-established integrated home-based records of maternal, newborn, and 118 child health. As a part of a national maternal and child health policy, all municipalities issue a 119 handbook to all women who report a pregnancy, and medical professionals record the health 120 information of the mother and child, including clinical outcomes (e.g., blood pressure and 121 birth weight) and incident diagnoses (e.g., HDP and LBW) during pregnancy. Mothers 122 seldom lose their Maternal and Child Health Handbooks (losing rate, <1%).[15] 123 124 HTP and cigarette smoking and other covariates 125 In the questionnaire, study participants were asked to indicate their smoking status (never, 126 once or a few times but not habitually, former, sometimes, or every day) for each HTP 127 available in the study period (Ploom Tech, Ploom Tech plus, Ploom S, IQOS, glo, glo sens, 128 and PULZE). If they answered “never” for all HTPs, we defined them as never HTP smokers; 129 the remaining participants were considered ever HTP smokers. 130 We also classified the status of combustible cigarette smoking (never/ever). For other 131 covariates, we included age, educational attainment (≤ 12 years [high school] or ≥ 13 years 132 [college or university]), occupation (manager or others), household income (<2 million JPY 133 [approximately 20,000 USD], 2 to <6 million JPY, and ≥ 6 million JPY), and comorbidity 134 (having hypertension or diabetes).[17] 135 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 8 136 Statistical analysis 137 Descriptive statistics were computed, and t-test or chi-squared test was performed. We 138 assessed the prevalence of ever HTP smokers among post-delivery and currently pregnant 139 women. Additionally, we described detailed HTP smoking status cross-classified according 140 to the combustible cigarette smoking status of currently pregnant and post-delivery women. 141 To assess the potential association between HTP smoking and perinatal risk of HDP 142 and LBW, we restricted the sample to 558 post-delivery women who could complete all the 143 assessments during their pregnancy (Table 1). In the multivariable logistic regression 144 analyses, the odds ratio (OR) and 95% confidence interval (CI) of ever HTP smokers for 145 HDP risk were estimated with adjustment for age (model 1, the main model in the present 146 study). The reference group comprised never HTP smokers. In model 2, we fully adjusted for 147 other explanatory variables (combustible cigarette smoking, educational attainment, 148 occupation, household income, and comorbidity) and excluded 64 participants with missing 149 information on household income. The same analyses were performed for LBW. For 150 sensitivity analysis, we conducted a stratified analysis with respect to combustible cigarette 151 smoking (never/ever). 152 Alpha was set at 0.05, and all P-values were two sided. Data were analyzed using 153 STATA/MP13.1 (StataCorp LLC, College Station, TX). 154 155

156 Among 558 post-delivery women, the incidences of HDP and LBW were 7.3% (n=41) and 157 10.0% (n=56), respectively, and the prevalence of ever HTP smokers was 11.7% (n=65, 158 Table 1). Furthermore, among 365 currently pregnant women, the prevalence of ever HTP 159 smokers was 12.6% (n=46), which did not differ from that of HTP smokers among post-160 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 9 delivery women (P=0.66). Among currently pregnant women, 4.4% of former combustible 161 cigarette smokers reported smoking HTPs during pregnancy (Table 2), corresponding to 162 1.1% (4 out of 365) of current HTP smokers. 163 Among post-delivery women, the HDP incidence was higher in ever HTP smokers than 164 in never HTP smokers (13.8% vs. 6.5%; Table 1). Similarly, the incidence of LBW was 165 higher among ever HTP smokers than among never HTP smokers (18.5% vs. 8.9%, Table 1). 166 When stratified by combustible cigarette smoking, a similar tendency was observed among 167 never and ever combustible cigarette smokers (Table 1). 168 In the regression analysis, the age-adjusted ORs for HDP and LBW were elevated in 169 ever HTP smokers (model 1, Figure 1); the ORs for HDP and LBW were 2.48 (95% CI, 170 1.11–5.53) and 2.36 (95% CI, 1.16–4.78), respectively. Although the elevated ORs were 171 attenuated after fully controlling for other covariates, the tendency remained elevated (model 172 2, Figure 1). In the same regression analyses (model 2), while ever combustible cigarette 173 smokers did not predict perinatal outcomes, managerial workers predicted the incidence of 174 HDP and LBW; the ORs for HDP and LBW were 3.92 (95% CI 1.16–13.2) and 3.74 (95% CI 175 1.41–9.93), respectively. When stratified by combustible cigarette smoking, a similar 176 tendency was observed independently in never and ever combustible cigarette smokers 177 (Figure 1). For instance, among never combustible cigarette smokers, the age-adjusted OR of 178 HTP use for LBW was 4.82 (95% CI, 1.19–19.6). 179 180

181 During the COVID-19 pandemic in Japan, the incidence of HTP use among pregnant women 182 is likely to exceed 10%, and we found that HTP use may be associated with perinatal risk of 183 HDP and LBW. Although the impact was attenuated after controlling for other potential 184 explanatory factors and the significance disappeared due to weak statistical power, the 185 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 10 maternal risk might be high independent of combustible cigarette smoking. This result seems 186 to be reliable because the incidence estimate of approximately 7% HDP found in our study 187 (using Maternal and Child Health Handbooks) is consistent with the general statistics 188 reported for Japanese pregnant women.[14] In addition, pregnant women of high 189 socioeconomic status independently predicted the risk of HDP, which might also support our 190 findings because they are known to use HTP more frequently than women of lower 191 socioeconomic status.[17] 192 We also found that LBW, a well-known smoking-related neonatal risk,[18] was 193 associated with HTP use. In fact, the incidence of HTP use doubled the risk of LBW, and the 194 association was stronger among never combustible cigarette smokers. These results seem to 195 be reliable because the incidence estimate of approximately 10% LBW found in our study 196 (using Maternal and Child Health Handbooks) is consistent with the general statistics 197 reported for Japanese pregnant women.[19] This also implies that aerosols of HTPs 198 containing nicotine and other inhalable substances can cause acute adverse health events on 199 the development of infants. 200 To the best of our knowledge, this is the first report of a potential association between 201 HTP use and perinatal risks. Although smoking plays a controversial role,[9] recent evidence 202 suggests that combustible cigarette smoking is associated with increased HDP risk.[10, 11] 203 Another study also reported the risk of snuff use for preeclampsia, a severe phenotype of 204 HDP.[20] Although the biological and genetic pathways (e.g., CYP2A6 and nicotine) 205 underlying the associations observed in different phenotypes of HDP (e.g., preeclampsia and 206 gestational hypertension) have not been elucidated,[21] HDP is recognized as a systemic 207 disease attributable to placental circulatory dysfunction.[22] In experimental research, aerosol 208 from HTPs was found to damage vascular endothelial function in rats.[5] Therefore, HDP 209 risk associated with HTP use may involve acute and chronic vascular damage, irrespective of 210 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 11 combustible cigarette smoking. Furthermore, as concluded in a recent systematic review, 211 smoking is a strong risk factor for LBW.[18] Thus, given the fact that HTPs are smoking 212 devices, our observed results are in line with established knowledge. 213 Finally, the impression of HTPs as a healthy alternative is promoted by the advertising 214 of HTPs.[4] Indeed, among currently pregnant women, approximately 4% of former 215 combustible cigarette smokers reported smoking HTPs in the present study. This result might 216 reflect a change from combustible cigarettes to HTP smoking during pregnancy. However, 217 our findings imply that HTP use is at least not a healthy alternative. Evidence for unfavorable 218 health outcomes regarding HTPs is still lacking, particularly in the young population of 219 reproductive age. Insufficient health knowledge may have led to the current increase of HTP 220 use among pregnant women, as reflected in our results and the latest statistics in Japan.[2, 3] 221 However, the question remains as to how multidimensional factors of the COVID-19 222 pandemic (e.g., the infection, mental health, and socioeconomic factors) and the smoking 223 behaviors of others (e.g., partners and family) affect the association between HTP use and 224 perinatal risks. Our sequential series of the JACSIS study planned in 2021 may provide 225 updates regarding the present results. 226 Our study had some limitations. First, our cross-sectional design does not allow to 227 conclude causal mechanisms between HTP use and perinatal risks. However, the prevalence 228 of HDP and HTP smokers were mostly parallel to the general population in Japan.[2, 3, 14] 229 In addition, the incidence of HTP use did not differ between post-delivery and currently 230 pregnant women in our study. Second, recall and reporting bias cannot be discarded. Because 231 self-report-based smoking status among pregnant women tends to misclassify ever smokers 232 as never smokers,[23] our estimates might be biased toward the null. Third, the perinatal 233 clinical information was self-reported and not based on medical charts, thereby limiting the 234 precision of the results. However, all participants were asked to base their responses on their 235 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 12 Maternal and Child Health Handbooks, a well-established home-base maternal and neonatal 236 record during pregnancy.[16] Therefore, this limitation might not have affected our results or 237 at least not largely. Despite these limitations, the strengths of the study included detailed 238 information for HTPs, which covered all HTPs available during the study period. 239 Additionally, this is the first report regarding the status of HTP use among pregnant women 240 in Japan, and it highlights the potentially elevated maternal and neonatal risks associated with 241 HTP use. Additionally, besides the present study, no other human studies to date have 242 assessed the potential effect of the maternal use of new tobacco products (i.e., e-cigarette and 243 HTP) on perinatal health.[24] Therefore, our findings shed light and motivate further 244 investigations to estimate the life-threatening perinatal risks associated with new tobacco 245 products. 246 In conclusion, the incidence of HTP use seems to exceed 10% among pregnant women, 247 and HTP smoking may be associated with increased maternal and neonatal risks in Japan. 248 With no doubt, smoking in reproductive age can cause unfavorable perinatal outcomes.[25] 249 Hence, efforts should be made to investigate the risk of HTP use in reproductive age, and 250 school-based tobacco prevention and cessation programs should be conducted regardless of 251 product types to prevent life-threatening perinatal complications and deaths. 252 253 ACKNOWLEDGMENTS 254 We would like to thank Editage (www.editage.com) for English language editing. 255 256 FUNDING 257 This study was partly supported by Health, Labour and Welfare Sciences Research Grants 258 (20FA1005) and the Japan Society for the Promotion of Science (JSPS KAKENHI 259 JP18K17351). 260 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 13 261 DATA AVAILABILITY STATEMENT 262 The data that support the findings of this study are available on reasonable request. However, 263 restrictions apply to the availability of these data due to personal identification; research data 264 are not shared. If any person wishes to verify our data, they are most welcome to contact the 265 corresponding author. 266 267 CONFLICT OF INTEREST 268 The authors declare no potential conflicts of interest. 269 270 AUTHOR CONTRIBUTIONS 271 Conception and design: M Zaitsu, T Tabuchi; Development of methodology: M Zaitsu, Y 272 Hosokawa, S Okawa; Acquisition of data: S Okawa, A Hori, and T Tabuchi; Analysis and 273 interpretation of data: M Zaitsu, Y Hosokawa; Writing, review and/or revision of the 274 manuscript: All authors; Study supervision: T Tabuchi. 275 276 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 14

277 1 Tabuchi T, Gallus S, Shinozaki T, et al. Heat-not-burn tobacco product use in Japan: its 278 prevalence, predictors and perceived symptoms from exposure to secondhand heat-not-279 burn tobacco aerosol. Tob Control 2018;27:e25–e33. 280 2 Hori A, Tabuchi T, Kunugita N. Rapid increase in heated tobacco product (HTP) use 281 from 2015 to 2019: from the Japan “Society and New Tobacco” Internet Survey 282 (JASTIS). Tob Control 2020. 283 3 Odani S, Tabuchi. T Prevalence of heated tobacco product use in Japan: the 2020 JASTIS 284 study. Tob Control 2021. Doi: 10.1136/tobaccocontrol-2020-056257 285 4 Hair EC, Bennett M, Sheen E, et al. Examining perceptions about IQOS heated tobacco 286 product: consumer studies in Japan and Switzerland. Tob Control 2018;27(Suppl 1):s70–287 3. 288 5 Nabavizadeh P, Liu J, Havel CM, et al. Vascular endothelial function is impaired by 289 aerosol from a single IQOS HeatStick to the same extent as by cigarette smoke. Tob 290 Control 2018;27(Suppl 1):s13–9. 291 6 Simonavicius E, McNeill A, Shahab L, et al. Heat-not-burn tobacco products: a 292 systematic literature review. Tob Control 2019;28:582–94. 293 7 Duley L. The global impact of pre-eclampsia and eclampsia. Semin Perinatol 294 2009;33:130–7. 295 8 Hasegawa J, Sekizawa A, Tanaka H, et al. Current status of pregnancy-related maternal 296 mortality in Japan: a report from the Maternal Death Exploratory Committee in Japan. 297 BMJ Open 2016;6:e010304. 298 9 England L, Zhang J. Smoking and risk of preeclampsia: a systematic review. Front Biosci 299 2007;12:2471–83. 300 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 15 10 Hayashi K, Matsuda Y, Kawamichi Y, et al. Smoking during pregnancy increases risks of 301 various obstetric complications: a case-cohort study of the Japan Perinatal Registry 302 Network database. J Epidemiol 2011;21:61–6. 303 11 Tanaka K, Nishigori H, Watanabe Z, et al. Higher prevalence of hypertensive disorders of 304 pregnancy in women who smoke: the Japan environment and children’s study. Hypertens 305 Res 2019;42:558–66. 306 12 Rakuten Insight Inc. https://insight.rakuten.co.jp/en/aboutus.html (Accessed 11 Feb 307 2021). 308 13 Tabuchi T, Shinozaki T, Kunugita N, et al. Study profile: The Japan “Society and New 309 Tobacco” Internet Survey (JASTIS): A longitudinal internet cohort study of heat-not-burn 310 tobacco products, electronic cigarettes, and conventional tobacco products in Japan. J 311 Epidemiol 2019;29:444–50. 312 14. Umesawa M, Kobashi G. Epidemiology of hypertensive disorders in pregnancy: 313 prevalence, risk factors, predictors and prognosis. Hypertens Res 2017;40:213–20. 314 15 Fujimoto S, Nakamura Y, Ikeda M et al. Utilization of maternal and child health 315 handbook in Japan. Nihon Koshu Eisei Zasshi 2001;48:486–94. 316 16 Osaki K, Hattori T, Toda A, et al. Maternal and Child Health Handbook use for maternal 317 and child care: a cluster randomized controlled study in rural Java, Indonesia. J Public 318 Health (Oxf) 2019;41:170–82. 319 17 Igarashi A, Aida J, Kusama T, et al. Heated tobacco products have reached younger or 320 more affluent people in Japan. J Epidemiol 2021;31:187–93. 321 18. Abraham M, Alramadhan S, Iniguez C, et al. A systematic review of maternal smoking 322 during pregnancy and fetal measurements with meta-analysis. PLOS ONE 323 2017;12:e0170946. 324 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 16 19 Organization for Economic Cooperation and Development. OECD Family Database 325 [database on the Internet]. 2020. 326 https://www.oecd.org/els/family/CO_1_3_Low_birth_weight.pdf (accessed 28 Feb 2021). 327 20 England LJ, Levine RJ, Mills JL, et al. Adverse pregnancy outcomes in snuff users. Am J 328 Obstet Gynecol 2003;189:939–43. 329 21 Nakajima M, Yamagishi S, Yamamoto H, et al. Deficient cotinine formation from 330 nicotine is attributed to the whole deletion of the CYP2A6 gene in humans. Clin 331 Pharmacol Ther 2000;67:57–69. 332 22 Yoshihara T, Zaitsu M, Kubota S, et al. Pool walking may improve renal function by 333 suppressing the renin-angiotensin-aldosterone system in healthy pregnant women. Sci 334 Rep 2020:10:2891. 335 23 Nishihama Y, Nakayama SF, Tabuchi T, et al. Determination of urinary cotinine cut-off 336 concentrations for pregnant women in the Japan environment and children’s study 337 (JECS). Int J Environ Res Public Health 2020;17. 338 24 Larcombe AN. Early-life exposure to electronic cigarettes: cause for concern. Lancet 339 Respir Med 2019;7:985–992. 340 25 Atrash HK, Johnson K, Adams M, et al. Preconception care for improving perinatal 341 outcomes: the time to act. Matern Child Health J 2006;10(Suppl):S3–S11. 342 343 344 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 17 FIGURE LEGEND 345 Figure 1. Odds ratio of ever heated tobacco product smokers with hypertensive 346 disorders of pregnancy and low birth weight compared with never heated tobacco 347 product smokers. Age was adjusted in model 1, and other covariates (combustible cigarette 348 smoking, educational attainment, occupation, household income, and comorbidity) were 349 additionally adjusted in model 2. The samples for each analysis in model 2 were as follows: 350 n=494 (overall), n=370 (never combustible cigarette smokers), and n=124 (ever combustible 351 cigarette smokers) for hypertensive disorders of pregnancy; and n=478 (overall), n=310 352 (never combustible cigarette smokers), and n=118 (ever combustible cigarette smokers) for 353 low birth weight. Abbreviations: HTP, heated tobacco products; OR, odds ratio. 354 355 356 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 18 Table 1. Characteristics of 558 post-delivery women and 365 currently pregnant women 357 Characteristics N (%) or mean (SD) Post-delivery women Currently pregnant women Never HTP smokers Ever HTP smokers Never HTP smokers Ever HTP smokers Overall n=493 n=65 n=319 n=46 Maternal and neonatal risk Hypertensive disorders of pregnancy 32 (6.5%) 9 (13.8%)* NA NA Low birth weight <2500 g 44 (8.9%) 12 (18.5%)* NA NA Preterm birth <37 weeks 19 (3.9%) 4 (6.2%) NA NA Imminent preterm birth 82 (16.6%) 18 (27.7%)* NA NA Age 32.4 (4.1) 30.9 (4.2)** 31.9 (4.3) 31.3 (4.7) Ever combustible cigarette smoking 82 (16.6%) 55 (84.6%)*** 54 (16.9%) 41 (89.1%)*** Educational attainment ≥ 13 years 410 (83.2%) 37 (56.9%)*** 278 (87.1%) 31 (67.4%)** Managerial workers 19 (3.9%) 5 (7.7%) 16 (5.0%) 2 (4.3%) Comorbidity of hypertension or diabetes 35 (7.1%) 4 (6.2%) 4 (1.3%) 4 (8.7%)** Household income n=436 n=58 n=263 n=41 <200 million JPY 13 (3.0%) 3 (5.2%) 6 (2.3%) 1 (2.4%) 200 to <600 million JPY 200 (45.9%) 30 (51.7%) 115 (43.7%) 19 (46.3%) ≥ 600 million JPY 223 (51.1%) 25 (43.1%) 142 (54.0%) 21 (51.2%) Never combustible cigarette smokers n=411 n=10 n=265 n=5 Maternal and neonatal risk Hypertensive disorders of pregnancy 26 (6.3%) 1 (10.0%) NA NA Low birth weight <2500 g 34 (8.3%) 3 (30.0%)* NA NA Preterm birth <37 weeks 17 (4.1%) 0 (0%) NA NA Imminent preterm birth 69 (16.8%) 3 (30.0%) NA NA Age 32.2 (4.0) 33.3 (2.3) 31.7 (4.3) 30.2 (1.8) Educational attainment ≥ 13 years 348 (84.7%) 7 (70%) 235 (88.7%) 4 (80.0%) Managerial workers 16 (3.9%) 1 (10%) 14 (5.3%) 0 (0%) Comorbidity of hypertension or diabetes 24 (5.8%) 0 (0%) 4 (1.5%) 0 (0%) Household income n=361 n=9 n=219 n=5 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 19 <200 million JPY 10 (2.8%) 0 (0%) 5 (2.3%) 0 (0%) 200 to <600 million JPY 160 (44.3%) 4 (44.4%) 97 (44.3%) 3 (60.0%) ≥ 600 million JPY 191 (52.9%) 5 (55.6%) 117 (53.45) 2 (40.0%) Ever combustible cigarette smokers n=82 n=55 n=54 n=41 Maternal and neonatal risk Hypertensive disorders of pregnancy 6 (7.3%) 8 (14.5%) NA NA Low birth weight <2500 g 10 (12.2%) 9 (16.4%) NA NA Preterm birth <37 weeks 2 (2.4%) 4 (7.3%) NA NA Imminent preterm birth 13 (15.9%) 15 (27.3%) NA NA Age 33.5 (4.3) 30.5 (4.3)*** 32.9 (4.2) 31.4 (5.0) Educational attainment ≥ 13 years 62 (75.6%) 30 (54.5%)** 43 (79.6%) 27 (65.9%) Managerial workers 3 (3.7%) 4 (7.3%) 2 (3.7%) 2 (4.9%) Comorbidity of hypertension or diabetes 11 (13.4%) 4 (7.3%) 0 (0%) 4 (9.8%)* Household income n=75 n=49 n=44 n=36 <200 million JPY 3 (4.0%) 3 (6.1%) 1 (2.3%) 1 (2.8%) 200 to <600 million JPY 40 (53.3%) 26 (53.1%) 18 (40.9%) 16 (44.4%) ≥ 600 million JPY 32 (42.7%) 20 (40.8%) 25 (56.8%) 19 (52.8%) Abbreviation: HTP, heated tobacco product; NA, not applicable. 358 *P<0.05, **P<0.01, ***P<0.001 for chi-squared test or t-test. 359 360 361 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint 20 Table 2. Detailed smoking status and use of heated tobacco products cross-classified 362 according to combustible cigarette smoking status 363 Characteristics HTP smoking status Never Former Current Total Post-delivery women, n=558 Never combustible cigarette smokers 411 (97.6%) 9 (2.1%) 1 (0.2%) 421 (100%) Former combustible cigarette smokers 79 (64.2%) 32 (26.0%) 12 (9.8%) 123 (100%) Current combustible cigarette smokers 3 (21.4%) 9 (64.3%) 2 (14.3%) 14 (100%) Currently pregnant women, n=365 Never combustible cigarette smokers 265 (98.1%) 5 (1.9%) 0 (0%) 270 (100%) Former combustible cigarette smokers 54 (59.3%) 33 (36.3%) 4 (4.4%) 91 (100%) Current combustible cigarette smokers 0 (0%) 4 (100%) 0 (0%) 4 (100%) Abbreviation: HTP, heated tobacco product. 364 *P<0.05, **P<0.01, ***P<0.001 for chi-squared test or t-test. 365 366 All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprintthis version posted April 17, 2021. ; https://doi.org/10.1101/2021.04.12.21255292doi: medRxiv preprint