Pregnancy outcomes for nulliparous women of advanced maternal age in South Australia, 1998-2008

Background Child bearing in the later reproductive years has become increasingly common in Australia with potential implications for clinical practice. Aim To examine pregnancy outcomes for nulliparous women of advanced maternal age with singleton pregnancies. Methods A retrospective population-based cohort study was conducted to compare the pregnancy outcomes for women aged 3539years and =40years with women aged 2529years, analysing 34695 records from the South Australian Perinatal Database between 1998 and 2008. Results Pre-existing hypertension [relative risks (RR) 1.98 and 2.94 for women aged 3539years and =40years, respectively], placenta praevia (RR 2.88 and 3.68), suspected intrauterine growth restriction (RR 1.33 and 1.77) and gestational diabetes (RR 1.97 and 2.53) increased with age. Women of advanced maternal age were more likely to have not laboured prior to birth (RR 2.19 and 3.28), be induced (RR 1.12 and 1.27) and have a breech presentation (RR 1.57 and 1.60). The likelihood of fetal distress increased with advancing maternal age (RR 1.15 and 1.24). Regression analyses revealed women of advanced maternal age were significantly more likely to have small for gestational age infants [adjusted odds ratios (AOR) 1.26 and 1.50], preterm birth (AOR 1.26 and 1.43), elective caesarean [relative risk ratios (RRR) 2.55 and 4.52], emergency caesarean (RRR 1.59 and 2.21) and experience a perinatal death (RRR 1.94 and 2.18). Conclusions The likelihood of pre-existing medical conditions, obstetric complications, adverse labour and birth outcomes and complications increased with advancing maternal age. Advanced maternal age was also independently associated with selected adverse pregnancy and infant outcomes.