The perinatal effects of delayed childbearing

Obstet Gynecol. 2005 Jun;105(6):1410-8. doi: 10.1097/01.AOG.0000163256.83313.36.


Objective: To determine if the rates of pregnancy complications, preterm birth, small for gestational age, perinatal mortality, and serious neonatal morbidity are higher among mothers aged 35-39 years or 40 years or older, compared with mothers 20-24 years.

Methods: We performed a population-based study of all women in Nova Scotia, Canada, who delivered a singleton fetus between 1988 and 2002 (N = 157,445). Family income of women who delivered between 1988 and 1995 was obtained through a confidential linkage with tax records (n = 76,300). The primary outcome was perinatal death (excluding congenital anomalies) or serious neonatal morbidity. Analysis was based on logistic models.

Results: Older women were more likely to be married, affluent, weigh 70 kg or more, attend prenatal classes, and have a bad obstetric history but less likely to be nulliparous and to smoke. They were more likely to have hypertension, diabetes mellitus, placental abruption, or placenta previa. Preterm birth and small-for-gestational age rates were also higher; compared with women aged 20-24 years, adjusted rate ratios for preterm birth among women aged 35-39 years and 40 years or older were 1.61 (95% confidence interval [CI] 1.42-1.82; P < .001) and 1.80 (95% CI 1.37-2.36; P < .001), respectively. Adjusted rate ratios for perinatal mortality/morbidity were 1.46 (95% CI 1.11-1.92; P = .007) among women 35-39 years and 1.95 (95% CI 1.13-3.35; P = .02) among women 40 years or older. Perinatal mortality rates were low at all ages, especially in recent years.

Conclusion: Older maternal age is associated with relatively higher risks of perinatal mortality/morbidity, although the absolute rate of such outcomes is low.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Family Planning Services
  • Female
  • Humans
  • Income
  • Infant Mortality
  • Infant, Newborn
  • Logistic Models
  • Maternal Age*
  • Nova Scotia
  • Obstetric Labor, Premature / epidemiology
  • Parity
  • Pregnancy
  • Pregnancy Complications
  • Pregnancy Outcome*
  • Prenatal Care
  • Smoking