Risk of preterm birth, low birthweight and small-for-gestational-age infants in pregnancies with adenomyosis: A cohort study of the Japan Environment and Children's Study.

INTRODUCTION: This study evaluated the risk of preterm birth, low birthweight and small-for-gestational-age neonates born to mothers with adenomyosis during pregnancy.

MATERIAL AND METHODS: We used the results of a Japanese nationwide prospective birth cohort study, identifying 93 668 singleton deliveries from 2011 to 2014. We identified 314 pregnancies with adenomyosis using self-reported questionnaires. Multiple logistic regression analyses were conducted to examine whether adenomyosis was associated with adverse pregnancy outcome. Maternal age, smoking status, method of conception, history of parity, fibroids, endometriosis and body mass index before pregnancy were analyzed as confounding factors.

RESULTS: Multiple logistic regression analysis showed that pregnancy with adenomyosis was a risk factor for preterm birth at less than 37 weeks (adjusted odds ratio [aOR: 2.49, 95% confidence interval [CI] 1.89-3.41), preterm birth at less than 34 weeks (aOR 1.91, 95% CI 1.02-3.55), low birthweight <2500 g (aOR 1.83, 95% CI 1.36-2.45), low birthweight <1500 g (aOR 2.39, 95% CI 1.20-4.77) and small-for-gestational-age neonates (aOR 1.68, 95% CI 1.13-2.51).

CONCLUSIONS: This study found that pregnancy with adenomyosis was associated with preterm birth, low birthweight and small-for-gestational-age neonates.