Adverse maternal and perinatal pregnancy outcomes related to very advanced maternal age in primigravida and multigravida in the Netherlands: a population based cohort

Introduction: The age at which women give birth is rising steadily in the western world. Advanced maternal age has been associated with adverse pregnancy outcomes. We assessed the association between advanced maternal age and the risk of adverse maternal and perinatal outcome in primigravid and multigravid women. Material and methods: The study was a population-based cohort study and included women giving birth between January 2000 and December 2018 using data from the Dutch perinatal registration of Perined. Women were divided into age groups. We compared outcomes between women of 40-44, 45-49, and over 50 years old (the study groups) with women of 25-29 years old (reference group), stratified for parity. We employed multivariable regression to correct for possible confounders including methods of conception, multiple pregnancies, ethnicity, and socio-economic status. Our primary outcomes were maternal and perinatal mortality. Secondary outcomes included common maternal and perinatal complications, as well as cesarean section rate. Results: A cohort of 3 700 326 women gave birth during the study period. Of these women, 3.2% were above 40 years of age. Maternal mortality was rare in all groups, but significantly higher in multigravid women over 50 years old. Perinatal mortality was significantly higher in all pregnancies of women over 40 years old, but not for primigravida over 50 years old. The most notable results with the steepest increase were in maternal complications. Both primigravida and multigravida over 40 years old were at a two times higher risk of perinatal mortality, cesarean section, gestational diabetes, hypertensive disorders, and a low Apgar score after 5 minutes. The risk for women over 45 was almost tripled for perinatal mortality and gestational diabetes and six times higher for cesarean section. Women over 50 years old had a seven times higher risk of cesarean section, a four times higher risk of gestational diabetes, postpartum hemorrhage, and neonatal intensive care unit admission, and a 10 times higher risk of hypertensive disorders. Conclusions: The risk of adverse maternal and perinatal outcomes for women over 40 years old surges as age increases. A novel aspect was the consistent increased risks not only for primigravid women but also for multigravida.