Association between FTO gene polymorphism and excess body weight in women from before to after pregnancy: A cohort study.

OBJECTIVE: The aim of this study was to examine the influence of the FTO-rs9939609 polymorphism on excess body weight in women during the reproductive transition from pre- to post-pregnancy.

METHODS: This was a prospective cohort study covering a period extending from before pregnancy to 2 and 4 years after pregnancy. A total of 435 women were first included in the study and, at last follow-up, 220 of them continued to participate in the study. The FTO-rs9939609 polymorphism was analyzed by the polymerase chain reaction/ restriction fragment length polymorphism (PCR/RFLP) method.

RESULTS: The FTO-rs9939609 polymorphism was associated with increasing weight and body mass index (BMI) during the follow-up period. Women carrying at least 1 risk allele (A) were significantly heavier (P < .05, up to 4.24 kg) and had a 1.30 kg/m2 higher BMI. Although the AA genotype was significantly associated with a greater risk compared to the wild-type genotype in the cross-sectional analysis, the results did not differ significantly in the longitudinal analysis (AA genotype, β = 1.20, 95% CI 0.85-1.68), even after adjustment for pre-pregnancy age, smoking before pregnancy, parity at pregnancy, and gestational weight gain.

CONCLUSIONS: The FTO-rs9939609 polymorphism was associated with increased weight and BMI in mothers before and after pregnancy. However, we found no significant effect of the polymorphism on excess body weight of women during the reproductive trajectory.