Objective: The aim of this study was to investigate the influence of maternal age on perinatal and obstetric outcome in women aged 40-44 years and those 45 years or older and to estimate whether adverse outcome was related to intercurrent illness and pregnancy complications.
Methods: National prospective, population-based, cohort study in women aged 40-44 years and those 45 years or older and in a control group of women aged 20-29 years who delivered during the period 1987-2001. Adjusted odds ratios (OR) were calculated after adjustments for significant malformations, maternal pre-existing diseases, and smoking. Main outcome measures were perinatal mortality, intrauterine fetal death, neonatal death, preterm birth, and preeclampsia.
Results: During the 15-year period, there were 1,566,313 deliveries (876,361 women were 20-29 years of age, 31,662 were 40-44 years, and 1,205 were > or = 45 years). Perinatal mortality was 1.4%, 1.0%, and 0.5% in women 45 years or older, 40-44, and 20-29 years, respectively. Adjusted OR for perinatal mortality was 2.4 (95% confidence interval [CI] 1.5-4.0) in women aged 45 years or older, compared with 1.7 (95% CI 1.5-1.9) in women 40-44 years. Adjusted OR for intrauterine fetal death was 3.8 (95% CI 2.2-6.4) in women aged 45 years or older, compared with 2.1 (95% CI 1.8-2.4) in women 40-44 years. Preterm birth, gestational diabetes, and preeclampsia were more common among women 40-44 years of age and those 45 years or older. Perinatal mortality was increased in women with intercurrent illness or pregnancy complications compared with women without these conditions, but there was no evidence that these factors became more important with increasing age.
Conclusion: Perinatal mortality, intrauterine fetal death, and neonatal death increased with age. There was also an increase in intercurrent illnesses and pregnancy complications with increasing age, but this did not entirely explain the observed increase in perinatal mortality with age.
Level of evidence: II-3