Objective: To investigate (1) whether there is an increasing trend in the mean maternal age at the birth of the first child and in the group of women giving birth at age 35 or older, and (2) the association between advanced maternal age and adverse perinatal outcomes in an Asian population.
Study design: We conducted a retrospective cohort study involving 39,763 Taiwanese women who delivered after 24 weeks of gestation between July 1990 and December 2003. Multivariable logistic regression was used to adjust for potential confounding variables.
Results: During the study period, the mean maternal age at the birth of the first child increased from 28.0 to 29.7 years, and the proportion of women giving birth at age 35 or older increased from 11.4% to 19.1%. Compared to women aged 20-34 years, women giving birth at age 35 or older carried a nearly 1.5-fold increased risk for pregnancy complications and a 1.6-2.6-fold increased risk for adverse perinatal outcomes. After adjusting for the confounding effects of maternal characteristics and coexisting pregnancy complications, women aged 35-39 years were at increased risk for operative vaginal delivery (adjusted odds ratio [OR] 1.5, 95% confidence interval [CI] 1.2-1.7) and cesarean delivery (adjusted OR 1.6, 95% CI 1.5-1.7), while women aged 40 years and older were at increased risk for preterm delivery (before 37 weeks of gestation) (adjusted OR 1.7, 95% CI 1.3-2.2), operative vaginal delivery (adjusted OR 3.1, 95% CI 2.0-4.6), and cesarean delivery (adjusted OR 2.6, 95% CI 2.2-3.1). In those women who had a completely uncomplicated pregnancy and a normal vaginal delivery, advanced maternal age was still significantly associated with early preterm delivery (before 34 weeks of gestation), a birth weight <1500 g, low Apgar scores, fetal demise, and neonatal death.
Conclusion: In this population of Taiwanese women, there is an increasing trend in the mean maternal age at the birth of the first child. Furthermore, advanced maternal age is independently associated with specific adverse perinatal outcomes.