Elevated risks of pregnancy complications and adverse outcomes with increasing maternal age

In the USA, between 1980 and 2004, the proportion of all births increased 2-fold in women aged > or = 30, 3-fold in women aged > or = 35 and nearly 4-fold in women aged > or = 40. The objective of this study was to evaluate the risks of pregnancy complications and adverse outcomes with increasing maternal age using national vital statistics data.

The study population included 8,079,996 live births of singletons of > or = 20 weeks among women aged 30-54 from the 1995-2000 US Birth Cohort Linked Birth/Infant Death Data Set. Outcomes were modelled by maternal age and parity using multinomial logistic regression to calculate adjusted odds ratios (AORs) and 95% confidence intervals.

The risks for most outcomes paralleled increasing maternal age including prolonged and dysfunctional labour, excessive labour bleeding, breech and malpresentation and primary Caesarean delivery. The highest AORs among women aged > or = 45 versus 30-34 by parity (primiparas and multiparas, respectively) were for chronic hypertension (3.70, 4.89), diabetes (2.19, 2.58), primary Caesarean (3.14, 2.85), excessive labour bleeding (1.54, 1.49), pregnancy hypertension (1.55, 2.13) and birth <32 weeks (2.11, 1.77).

Increasing maternal age is associated with significantly elevated risks for pregnancy complications and adverse outcomes, which vary by parity.