Risk of recurrence of small-for-gestational-age foetus after first pregnancy

The aim of this study was to assess the incidence of and to analyse factors related to the recurrence of small-for-gestational-age (SGA) neonates in the second pregnancy. A prospective observational study was conducted at a tertiary university hospital in Granada, Spain. A total of 7896 women who delivered their first and second singleton pregnancies at the hospital from 2003-2013 were included and evaluated all birth weights. Women whose first pregnancy was complicated by a SGA birth had a fivefold increased risk of recurrence (23.6% vs. 5.7%, p < .001). Multivariate analyses revealed that only SGA at first birth retained a statistically significant relationship, revealing that the other variables (maternal age, gestational age, interdelivery interval, maternal pre-pregnancy body mass index, occupation of the mother, smoking, hypertension, and diabetes mellitus) were confounders. Prevention of SGA in subsequent pregnancies by modification of established risk factors could be of limited utility based on the present results, supporting a genetic contribution to SGA recurrence. Impact statement The results support a genetic contribution on recurrence of SGA.