Pregnancy late in life: A hospital-based study of birth outcomes

Background: Pregnancy in older women is of great relevance, particularly in developed countries where many women experience pregnancy late in the childbearing age. Methods: A hospital-based data analysis of 9506 delivery records from 1998 to 2003 at the Liverpool Women's Hospital was undertaken to assess pregnancy outcomes in older women of reproductive age. Results: Overall, 2.4% of mothers were >40 years of age (advanced), 5.6% were <20 years (adolescents), and 92% were between 20 and 40 years. The prevalence of low birthweight (LBW), preterm birth, and small for gestational age by maternal age category followed a U-shaped curve with nadirs in the middle age classes. The gestational age of older mothers was 1 week shorter than that for women aged 26-30 years (p = 0.005). Primiparaes >40 years were at higher risk for delivering a LBW (9.4% vs. 5.3%, p = 0.005) or a very preterm baby (8.9% vs. 4.4%, p = 0.001) than were multiparous mothers of the same age. There was an association between maternal advanced age and LBW (adjusted OR [AOR], 1.7, 95% CI 1.4-2.5, p = 0.001), preterm birth (AOR 1.4, 95% CI 1.1-2.4, p = 0.04), or very preterm birth (AOR 1.6, 95% CI 1.2-3.5, p = 0.002) after controlling for prenatal alcohol and smoking exposure, household deprivation, maternal anemia, obesity, parity, and single parenthood. Conclusions: Pregnancy in older women is associated with adverse birth outcomes, particularly in primigravidas. Increased health promotion is required to highlight the risk of adverse birth outcomes in women who become pregnant for the first time in the late childbearing years.