Study Links Advanced Maternal Age to Moderate Increases in Birth Risks
A large-scale Swedish registry study examining over 300,000 births reveals that advanced maternal age, particularly past 45, correlates with increased risks of stillbirth and preterm delivery.
A study based on Swedish registry data covering over 300,000 births indicates that advanced maternal age—particularly over 45—is associated with a measurable increase in perinatal risks.
Social Trends in Motherhood
According to a report by the Taub Center, the average age of first-time mothers in Israel has risen significantly over the past two decades. Concurrently, the rate of births outside of marriage and those resulting from in vitro fertilization (IVF) has nearly doubled. This reflects a broader societal trend where women increasingly delay childparenthood, supported by medical advancements that mitigate age-related fertility decline. However, sociologists note that this option is not evenly distributed across the population, often correlating with higher education and socioeconomic standing.
The Swedish Population Study
To examine the health implications of delayed childbearing, researchers in Sweden analyzed over 300,000 singleton births between 2010 and 2022 using the National Birth Registry. Participants were divided into three age groups: 35–39 (the reference group), 40–44, and 45 and older. The study tracked complications such as stillbirth, neonatal mortality, and preterm birth before 34 weeks.
Risk Increments by Age Group
Compared to the 35–39 cohort, mothers aged 40–44 experienced a moderate yet consistent increase in risks. The incidence of stillbirth rose by approximately 27 percent (from 0.42 to 0.55 percent, or about one to two additional cases per thousand births). Perinatal mortality and preterm births before 34 weeks also showed statistically significant increases.
For mothers aged 45 and older, the rise in complications was more pronounced. The risk of stillbirth increased by roughly 80 percent, though absolute numbers remained relatively low at 0.83 percent compared to 0.42 percent in the reference group (about four additional cases per thousand). Perinatal mortality and preterm births nearly doubled in this oldest cohort, with 3 percent experiencing premature delivery.
Implications and Limitations
While the relative risks increase notably after age 45, the absolute risk of severe complications remains low for individual pregnancies. Public health researchers emphasize that while individual probabilities change moderately, large population datasets help identify patterns that inform obstetric care and counseling. Study limitations include the use of women aged 35–39 as a baseline rather than younger cohorts, and the observational nature of registry-based research.
