THURSDAY, Aug. 6, 2026 (HealthDay News) -- Higher body mass index (BMI) in childhood is associated with lower odds of childbirth as women age, according to a study published online Aug. 4 in JAMA Network Open.
Dorthe C. Pedersen, Ph.D., from Copenhagen University Hospital-Bispebjerg and Frederiksberg in Denmark, and colleagues examined whether trajectories of childhood BMI are associated with timing of first childbirth and infertility in women. The analysis included linked national register and school health examination data of 60,864 women aged 18 to 45 years.
The researchers found that women with an obesity trajectory in childhood had a lower risk for giving birth compared with those with an average trajectory, and this association decreased with increasing age (ages 25 to 29 years: hazard ratio, 0.78; ages 35 to 45 years: hazard ratio, 0.56). Women with an overweight trajectory during childhood showed a similar pattern. There were no associations observed between childhood BMI trajectories and primary or any infertility.
"Our findings suggest that less favorable BMI patterns from as young as 6 years old may increase a woman's risk of childlessness from their mid-20s onwards," Pedersen said in a statement. "By the time women reach their 30s, when many women start trying to conceive and fertility difficulties often become evident, the effects on reproductive capacity may already be established, underscoring the importance of preventive efforts focused on healthy growth and development in childhood."
One author disclosed ties to Novo Nordisk.
