Associations of maternal age with maternity care use and birth outcomes in primiparous women: a comparison of results in 1991 and 2008 in Finland

Objective To compare birth outcomes and maternity care use in 1991 and 2008 by age among primiparous Finnish women. Design Register‐based study. Setting Nationwide Medical Birth Register. Population All primiparous women in 1991 (n = 24 765) and 2008 (n = 23 511). Methods Women aged 35–39 and ≥40 years were compared with women aged 20–34 years in 1991 and 2008, using logistic regression to adjust for women's background. Main outcome measures Maternity care: prenatal visits, hospitalisation during pregnancy, labour induction, delivery mode, long postpartum hospital stay; and birth outcomes: birthweight, preterm birth, Apgar scores, intensive/observation unit, respiratory care, perinatal death. Results In both years, older women's deliveries were more often induced, instrumental, or by caesarean section. In 2008 compared with 1991, hospitalisations were lower and instrumental deliveries and labour induction were higher in older women. A significant decrease in adjusted odds ratios (OR, 95% confidence intervals) between 1991 and 2008 among women aged 35–39 was found for preterm birth (1.47, 1.18–1.84 versus 0.96, 0.86–1.07) and for intensive/observation unit (1.73, 1.47–2.05 versus 1.21, 1.07–1.37) and, among women aged ≥40 years, for intensive/observation unit (3.14, 2.30–4.29 versus 1.64, 1.31–2.07). The risk for perinatal death (1.66, 0.60–4.60 versus 2.69, 1.07–6.79) was higher in 2008 than in 1991 among women aged ≥40. Conclusions In 2008, older primiparous women still used more maternity care, had more interventions, and poorer birth outcomes than younger women, regardless of care advances. Additional risks declined among women aged 35–39 but not among aged ≥40.