Maternal age over 40 years and pregnancy outcome: a hospital-based survey

Abstract

Objective: Increased risk for adverse pregnancy outcomes with advancing maternal age has been described but the strength of association remains debated, particularly in presence of confounding factors such as parity, twin pregnancy and pregnancy from assisted reproductive technologies. The aim of this study was to evaluate pregnancy outcomes in a large cohort of women aged over 40 years. The hypothesis was that advanced maternal age may be an independent risk factor for adverse pregnancy outcome.

Study design: We reviewed the clinical records of 56,211 women who delivered at Sant'Anna University Hospital, Turin, Italy, in the period between 2009 and 2015. Of these, 3798 women aged over 40 years were divided into two age groups (40 - 44 years and ≥45 years). Women of any parity, with singleton or twin pregnancies, or with assisted reproductive technology pregnancies were included. Women aged less than 40 years were considered as controls. Primary outcome measures were maternal and perinatal complications. Comparisons were performed using Chi-square test and Fisher's exact test. Univariate analysis and logistic regression analysis were performed to test the possible independent role of maternal age as a risk factor for adverse pregnancy outcome.

Results: Maternal age was an independent risk factor for gestational diabetes (age 40-44 years: odds ratios (OR) 2.10, 95% CI 1.80-2.45; age ≥45 years: OR 2.83, 95% CI 1.79-4.46) and early-onset preeclampsia (age 40-44 years: OR 2.10, 95% CI 1.63-2.70; age ≥45 years: OR 3.16, 95% CI 1.68-5.94). The risk for placenta praevia was higher in the women aged 40-44 years (OR 1.87, 95% CI 1.36-2.57). Neonatal outcomes were similar among groups, except for the rate of birth weight less than 2500 g, which was higher in women aged 40-44 years (OR 1.27, 95% CI 1.12-1.42). However, older women showed an overall higher incidence of preterm birth.

Conclusions: Maternal age over 40 years is an independent risk factor for adverse pregnancy outcomes, particularly for the mother. Pregnancies in women over 40 years should be considered at risk and carefully monitored with individualized care protocols.

Keywords: Advanced maternal age; assisted reproductive technologies; perinatal outcomes; pregnancy outcomes; twin pregnancy.