Delayed childbearing--are there any risks?

OBJECTIVE: To determine whether women delivering their first child at age 35 years or older are at increased risk of adverse (non-genetic) pregnancy outcomes. DESIGN AND SETTING: A cross-sectional analytic study of singleton deliveries in Northern Sydney Area Health Service (NSAHS) hospitals. PARTICIPANTS: All women aged > or = 20 years delivering their first child between 1 January 1990 and 31 December 1991. MAIN OUTCOME MEASURES: Obstetric complications and procedures, type of delivery and neonatal outcomes. RESULTS: Compared with women aged 20-29 years, women delivering their first child at > or = 35 years were at increased risk of pre-existing maternal hypertension (adjusted odds ratio [OR], 3.5; 95% confidence interval [CI], 1.7-7.0), antepartum haemorrhage (adjusted OR, 2.4; 95% CI, 1.6-3.7), preterm delivery (33-36 weeks) (adjusted OR, 2.0; 95% CI, 1.5-2.8) and breech presentation (adjusted OR, 1.8; 95% CI, 1.3-2.4). Women aged > or = 35 years were also substantially more likely to have an operative delivery, induced labour and/or epidural anaesthesia. Neither these women nor their infants were at increased risk of pregnancy-induced hypertension, gestational diabetes, threatened premature labour, postpartum haemorrhage, very preterm delivery (< or = 32 weeks), perinatal death, low Apgar scores or the need for neonatal resuscitation. CONCLUSIONS: Women who delay the birth of their first child face some increased risks, but these risks, for the most part, are manageable in the context of modern obstetric care.