Background Postpartum weight retention is important risk factor for obesity in reproductive age women. The role of fibre intake still needs clarification, being among those dietetic factors that may be associated with a positive evolution of postpartum weight variation.

Objectives To evaluate the effect of fibre intake on the evolution of maternal body mass index (BMI) from pregnancy to postpartum, and to identify dietary patterns associated with fibre intake.

Methods A cohort of 370 pregnant women was followed until the sixth month of postpartum. Food intake was obtained using food-frequency questionnaire. Focused principal component analysis was used centered on postpartum weight retention and on total dietary fibre intake. Obesity risk was a variable defined to indicate unfavourable evolution of BMI in postpartum. Poisson regression was used to estimate the association between fibre intake and obesity risk.

Results Participants retained a median of 4.4 kg (IR 0.6; 7.9), and obesity risk was present in 55.1% (n=189) of the sample. Individual food items did not have an important effect on weight retention. The highest contribution of fibre intake came from the consumption of beans. Consumption of bread and rice indicated a common Brazilian food pattern along with beans. In the multivariable model, inadequate fibre intake increased 24% (95% CI 1.05 to 1.47) the obesity risk, after adjusting for maternal age, prepregnancy BMI and total gestational weight gain.

Conclusion Maternal BMI showed an increasing trend from prepregnancy to postpartum. Adequate fibre intake may reduce obesity risk in the period following childbirth.