Higher maternal age linked to increased risk of adverse pregnancy outcomes
The risk of unfavourable pregnancy outcomes, such as chromosomal abnormalities, miscarriage and birth before 34 weeks of gestation, appears to be heightened in women aged >40 years than in those who are younger, according to a study from Denmark.
Researchers analysed data from a nationwide cohort of 369,516 singleton pregnancies followed from 11 to 14 weeks of gestation to delivery or termination of pregnancy. Pregnant women aged ≥35 years were divided into two advanced maternal age groups (35–39 years and ≥40 years) and compared with pregnant women aged 20–34 years. Adverse pregnancy outcomes investigated were chromosomal abnormalities, congenital malformations, miscarriage, stillbirth and birth before 34 weeks of gestation.
At least one of the selected adverse pregnancy outcomes occurred in 10.82 percent of pregnant women aged ≥40 years vs 5.46 percent of pregnant women aged 20–34 years (odds ratio [OR], 2.02; 99.8 percent CI, 1.78–2.29).
Compared with those who were younger, older pregnant women had a higher risk of chromosomal abnormalities (3.83 percent vs 0.56 percent; OR, 7.44; 5.93–9.34), miscarriage (1.68 percent vs 0.42 percent; OR, 3.10; 2.19–4.38) and birth before 34 weeks of gestation (2.01 percent vs 1.21 percent; OR, 1.66; 1.23–2.24). No such increase was observed in the risk of congenital malformations and stillbirth.
The risk prediction chart showed that advanced maternal age, use of assisted reproductive technology, nulliparous pregnancy, smoking during pregnancy and obesity all increased the absolute predictive risk of an adverse pregnancy outcome.
Findings of the present study indicate that while several factors increase the risk of adverse pregnancy outcomes, advanced maternal age drives a high proportion of the total risk score. This highlights the importance of closely monitoring pregnancies in women aged >40 years.