Advanced Maternal Age and Adverse Pregnancy Outcome: Evidence from a Large Contemporary Cohort

TLDR

Maternal age at childbirth has risen in high‑resourced countries, and advanced maternal age is linked to adverse maternal and perinatal outcomes, yet large contemporary population‑based cohort data controlling for key demographics remain scarce. This study aimed to assess the impact of advanced maternal age on pregnancy outcomes using a large contemporary population‑based cohort from the North Western Perinatal Survey. Pregnancy outcomes were compared across age groups (20‑29, 30‑34, 35‑39, ≥40) with log‑linear binomial regression adjusted for parity, ethnicity, social deprivation, and BMI, encompassing 215,344 singleton births. Women aged ≥40 had significantly higher risks of stillbirth, pre‑term and very pre‑term birth, macrosomia, large for gestational age, and Caesarean delivery, with risks independent of parity and persisting after adjustment for socioeconomic status, underscoring the need for evidence‑based counseling of older expectant mothers.

Abstract

Recent decades have witnessed an increase in mean maternal age at childbirth in most high-resourced countries. Advanced maternal age has been associated with several adverse maternal and perinatal outcomes. Although there are many studies on this topic, data from large contemporary population-based cohorts that controls for demographic variables known to influence perinatal outcomes is limited.We performed a population-based cohort study using data on all singleton births in 2004-2008 from the North Western Perinatal Survey based at The University of Manchester, UK. We compared pregnancy outcomes in women aged 30-34, 35-39 and ≥40 years with women aged 20-29 years using log-linear binomial regression. Models were adjusted for parity, ethnicity, social deprivation score and body mass index.The final study cohort consisted of 215,344 births; 122,307 mothers (54.19%) were aged 20-29 years, 62,371(27.63%) were aged 30-34 years, 33,966(15.05%) were aged 35-39 years and 7,066(3.13%) were aged ≥40 years. Women aged 40+ at delivery were at increased risk of stillbirth (RR = 1.83, [95% CI 1.37-2.43]), pre-term (RR = 1.25, [95% CI: 1.14-1.36]) and very pre-term birth (RR = 1.29, [95% CI:1.08-1.55]), Macrosomia (RR = 1.31, [95% CI: 1.12-1.54]), extremely large for gestational age (RR = 1.40, [95% CI: 1.25-1.58]) and Caesarean delivery (RR = 1.83, [95% CI: 1.77-1.90]).Advanced maternal age is associated with a range of adverse pregnancy outcomes. These risks are independent of parity and remain after adjusting for the ameliorating effects of higher socioeconomic status. The data from this large contemporary cohort will be of interest to healthcare providers and women and will facilitate evidence based counselling of older expectant mothers.