Background: Placenta accreta spectrum (PAS) is a life-threating complication in the field of obstetrics. Sometimes we face with unexpected PAS cases which is potentially higher maternal mortality and morbidity compared with expected cases. The present study was conducted to examine the prevalence of PAS and to elucidate its risk factors using a large Japanese birth cohort study. Methods: We reviewed the results of a nationwide prospective birth cohort study in Japan, and identified 90,554 participants treated from 2011 to 2014 in 15 regional centers. Multiple regression models were created to identify the risk factors for PAS. These data were obtained from self-reported questionnaires or patient medical records. Results: This analysis consisted of 202 cases of PAS (18 with placenta previa and 184 without placenta previa) and 90,352 cases without PAS. The multiple logistic regression analysis showed that placenta previa (adjusted odds ratio [aOR]: 12.86, 95% confidence interval [CI] 7.70–21.45, P < 0.001), assisted reproductive technology-related pregnancies (aOR: 6.78, 95% CI 4.54–10.14, P < 0.001), smoking during pregnancy (aOR: 1.95, 95% CI 1.15–3.31, P = 0.013), more than two previous cesarean sections (aOR: 2.51, 95% CI 1.35–4.67, P = 0.004), and uterine anomalies (aOR: 3.97, 95% CI 1.24–12.68, P = 0.020) increased the risk of PAS. Conclusion: In general population, placenta previa, assisted reproductive technology-related pregnancy, smoking during pregnancy, repeated cesarean sections, and uterine anomalies were risk factors for PAS in the Japanese population.

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There are limited studies on the long-term effects of natural/environmental disasters, especially nuclear disasters, on obstetric outcomes. This study aimed to review the results of perinatal outcomes immediately after the Great East Japan Earthquake (GEJE) and the Fukushima Daiichi Nuclear Power Plant accident, as well as their long-term trends over 8 years, in the Fukushima Health Management Survey. The annual population-based Pregnancy and Birth Survey is conducted as part of the Fukushima Health Management Survey. The Fukushima Prefecture government launched it to assess the health conditions of pregnant women and their neonates after the GEJE. The self-reported questionnaire was sent to 115,976 pregnant women by mail from January 2012, with 58,344 women responding to the questionnaire (50.3% response rate). Pregnancy complications, such as gestational hypertension, respiratory diseases, and mental disorders, increased in some women who were pregnant at the time of the earthquake and immediately after the earthquake. However, the direct effects on newborns, such as preterm birth, low birth weight, and congenital anomalies, were not immediately clear after the earthquake. Although there were significant differences in the occurrence of preterm birth and low birth weight among the districts, there was no change in the occurrences of preterm birth, low birth weight, or anomalies in newborns in Fukushima Prefecture from the fiscal year 2011 to the fiscal year 2018. Therefore, the long-term effects of the post-disaster radiation accident on perinatal outcomes are considered to be very small.

Aims/Introduction: To examine adverse outcomes in women with early‐diagnosed gestational diabetes mellitus using data from a large birth cohort study in Japan.Materials and Methods: This study analyzed data from singleton pregnancies in the Japan Environment and Children’s Study including births during 2011–2014. Mothers with an HbA1c level ≥6.5% in the first trimester, a history of diabetes mellitus, or steroid use during pregnancy were excluded. The participants were divided into three groups: control (without gestational diabetes mellitus), early‐diagnosed gestational diabetes mellitus (diagnosed before gestational week 24), and late‐diagnosed gestational diabetes mellitus (diagnosed after gestational week 24). Multiple logistic regression analysis was performed to calculate the risk of early‐diagnosed and late‐diagnosed gestational diabetes mellitus for adverse obstetrics outcomes.Results: In total, 100,376 eligible participants were included in this study. The number of individuals in control cases, early‐diagnosed gestational diabetes mellitus cases, and late‐diagnosed gestational diabetes mellitus cases was 98,090 (97.7%), 751 (0.7%), and 1,535 (1.5%), respectively. When control cases were used as reference, multiple logistic regression analysis revealed that early‐diagnosed gestational diabetes mellitus increased the risk of hypertensive disorders of pregnancy (adjusted odds ratio: 2.08, 95% confidence interval: 1.51–2.86), early‐onset hypertensive disorders of pregnancy (adjusted odds ratio: 1.91, 95% confidence interval: 1.01–3.65), and late‐onset hypertensive disorders of pregnancy (adjusted odds ratio: 1.92, 95% confidence interval: 1.29–2.86).Conclusion: Early‐diagnosed gestational diabetes mellitus is associated with serious obstetric complications. Our findings indicate the necessity of further investigations to validate the benefit of early screening for gestational diabetes mellitus in pregnant women.

The daily diet plays a role in systematic inflammation and may be one of the causes of preterm birth. We aimed to examine the effect of a daily proinflammatory diet before pregnancy on gestational age and birthweight using a large birth cohort in Japan. We used data of singleton pregnancies in the Japan Environment and Children's Study involving live birth from 2011 to 2014 to calculate the dietary inflammatory index. We used individual meals with 30 food parameters from a semiquantitative food frequency questionnaire, which assessed diet intake before pregnancy. Participants were categorized according to the quartile of dietary inflammatory index. A multiple logistic regression model was used to estimate the risk of a proinflammatory diet on preterm birth (PTB) before 37 or 34 weeks and low birthweight (LBW) less than 2,500 or 1,500 g, accounting for maternal age, body mass index before pregnancy, smoking status, education, and household income. After applying our inclusion criteria, 89,329 participants were eligible for the present study. Multiple regression analysis showed that the proinflammatory diet had an increased risk of PTB < 34 weeks (adjusted odds ratio: 1.29, 95% confidence interval [1.07, 1.55]) and <2,500‐g LBW (adjusted odds ratio: 1.08, 95% confidence interval [1.01, 1.16]) compared with the control. In conclusion, a proinflammatory diet before pregnancy was a risk factor for PTB < 34 weeks and LBW < 2,500 g. Therefore, proinflammatory diet needs to be controlled to improve perinatal prognosis.