Being born very preterm or with very low birth weight does not affect fertility in adulthood

Adults born very preterm (VP) or with very low birth weight (VLBW) do not appear to have reduced overall fertility, according to a study.

The study included 212 adults born VP or with VLBW and 202 who were born at term between January 1985 and March 1986. Their mean age was 34.67 years, and 52.2 percent were female.

The main outcome of the cumulative incidence of having the first alive child (ie, fertility) was compared between participants born VP or with VLBW and term-born participants using log-rank tests. Estimations were compared between early (<30 years) and late (≥30 years) reproductive windows.

Throughout the follow-up, the cumulative incidence of having the first alive child was lower in the VP/VLBW group than in the control group. The association between VP/VLBW and lower fertility was significant during the late reproductive window (hazard ratio [HR], 0.46, 95 percent confidence interval [CI], 0.31–0.68) but not during the early reproductive window (HR, 0.73, 95 percent CI, 0.47–1.14).

However, the observed association was attenuated after adjusting for neonatal factors (sex and family socioeconomic status) and childhood neurosensory impairment (HR, 0.59, 95 percent CI, 0.40–0.88) and childhood family factors (eg, parenting) (HR, 0.61, 95 percent CI, 0.40–0.92). Finally, the association disappeared after controlling for sociodemographic factors (eg, partnering) (HR, 0.78, 95 percent CI, 0.50–1.20).

Notably, partnering (ie, being married or cohabitating with a partner) showed the strongest magnitude association with fertility across both the early (HR, 7.87, 95 percent CI, 3.44–18.00) and late (HR, 3.95, 95 percent CI, 2.47–6.31) reproductive windows.

These findings indicate that partnering is key to reproductive success among adults born VP or with VLBW.