Association of maternal age 35 years and over and prenatal care utilization, preterm birth, and low birth weight, Mexico 2008-2019.

Abstract

To evaluate prenatal care utilization, low birth weight, and preterm birth among women aged 35 years and older in Mexico from 2008 to 2019. We conducted a historical cohort study of all singleton live births in Mexico from 2008 to 2019. Outcomes were inadequate prenatal care, preterm birth, and low birth weight. We compared outcomes among women aged 35-39, 40-44, and 45-49 years with births to women aged 20-34 years. We used logistic regression to account for individual, health system, and contextual confounders. We included a total of 19 526 922 births; 2325 725 (11.9%) were to women aged 35 years and older. Women aged 45-49 years had the lowest levels of education, were more likely to be uninsured, and came from highly marginalized municipalities while those aged 35-39years had the highest levels of education and insurance and came from the least marginalized municipalities. The odds of inadequate prenatal care (adjusted odds ratio [aOR] 1.12; 95% confidence interval [CI] 1.09-1.15), preterm birth (aOR 2.05; 95% CI 1.97-2.13), and low birth weight (aOR 2.03; 95% CI 1.95-2.12) were highest for women aged 45-49 years, compared with women aged 20-34 years. The odds of adverse perinatal outcomes increased progressively with age, but the odds of inadequate prenatal care (aOR 0.77; 95% CI 0.76-0.77) were lowest for women aged 35-39 years, when compared with women aged 20-34 years. Women who deliver at 35 years and over are a heterogeneous group in Mexico. Being 35 years old and older is associated with increases in preterm birth and low birth weight neonates. Women who give birth between 45 and 49 years may be especially vulnerable.