Association Between Gestational Weight Gain in Each Trimester and Weight Retention at 6 and 12 Months Postpartum: Results from a National Administrative Dataset in Brazil

To estimate the association between gestational weight gain (GWG) in the first, second, and third pregnancy trimesters and weight retention at 6 and 12 mo postpartum. Individual data from the Brazilian National Food and Nutrition Surveillance System from 2008–2020 were used. Cumulative GWG was calculated as the difference between the last weight measured in each trimester and self-reported pre-pregnancy weight, standardized for gestational age and pre-pregnancy body mass index (BMI) into z-scores using the Brazilian charts. Postpartum weight retention (PWR) was calculated as the difference between weight measured close to (±1 month) 6 and 12 months postpartum and self-reported pre-pregnancy weight and categorized as < 5 or ≥ 5 kg. Median, interquartile ranges (IQR), frequencies, and proportions were calculated. Maternal age (y), participation in the Bolsa Familia conditional cash transfer program (yes/no), and pre-pregnancy BMI (kg/m2) were used to adjust linear regression models. Among the 31,846 women included, 88.5% were < 35 y old; 77.2% participated in the Bolsa Familia program, and 52.7% were classified as normal weight before pregnancy. The median (IQR) cumulative GWG was 1.2 (0–2.8), 4.0 (1.2–7.0), and 9.0 (5.3–12.7) kg in the first, second, and third pregnancy trimesters, respectively. At 6 and 12 mo postpartum, 32.7% and 31.4% of the women had PWR ≥ 5 kg, respectively. The prevalence of PWR ≥ 5 kg at 6 and 12 mo was higher among women who gained weight > 90th percentile of the Brazilian charts than those who gained below those values (73.2 v. 29.6% for 6; 63.9 v. 28.7% for 12 mo, respectively). Each 1 z-score increase in the cumulative GWG in the first, second, and third trimesters was associated with an increase of 2.0, 2.3, and 2.4 kg, respectively, in the PWR at 6 mo. Similar trends were observed for PWR at 12 mo (P < 0.001 for all cases). GWG in all pregnancy trimesters was associated with PWR at 6 and 12 mo postpartum. The association between GWG in the first trimester and PWR highlights the importance of monitoring weight gain since the beginning of pregnancy to prevent the occurrence of adverse outcomes, such as maternal obesity, during the postpartum period. Bill & Melinda Gates Foundation.