Gestational weight gain charts: results from the Brazilian Maternal and Child Nutrition Consortium.

BACKGROUND

Monitoring gestational weight gain (GWG) is fundamental to ensure a successful pregnancy for the mother and the offspring. There are several international GWG charts, but just a few for low- and middle-income countries.

OBJECTIVES

To construct GWG charts according to pre-pregnancy BMI for Brazilian women.

METHODS

This is an individual patient data analysis using the Brazilian Maternal and Child Nutrition Consortium data, comprising 21 cohort studies. External validation was performed using "Birth in Brazil," a nationwide study. We selected adult women with singleton pregnancies who were free of infectious and chronic diseases, gestational diabetes, and hypertensive disorders; who delivered a live birth at term; and whose children were adequate for gestational age, and with a birth weight between 2500-4000 g. Maternal self-reported pre-pregnancy weight and weight measured between 10-40 weeks of gestation were used to calculate GWG. Generalized Additive Models for Location, Scale and Shape were fitted to create GWG charts according to gestational age, stratified by pre-pregnancy BMI.

RESULTS

The cohort included 7086 women with 29,323 weight gain measurements to construct the charts and 4711 women with 31,052 measurements in the external validation. The predicted medians for GWG at 40 weeks, according to pre-pregnancy BMI, were: underweight, 14.1 kg (IQR, 10.8-17.5 kg); normal weight, 13.8 kg (IQR, 10.7-17.2 kg); overweight, 12.1 kg (IQR, 8.5-15.7 kg); obesity, 8.9 kg (IQR, 4.8-13.2 kg). The 10th, 25th, 50th, 75th, and 90th percentiles were estimated. Results for internal and external validation showed that the percentages below the selected percentiles were close to those expected.

CONCLUSIONS

The charts proposed provide a description of GWG patterns according to gestational age and pre-pregnancy BMI among healthy Brazilian women with good neonatal outcomes. The external validation indicates that this new tool can be used to monitor GWG in the primary health-care setting and to test potential recommended values.