A longitudinal study of weight gain in pregnancy in Malawi: unconditional and conditional standards

Abstract

Background: To monitor weight gain during pregnancy and assess its relation with perinatal health outcomes, both unconditional (cross-sectional) and conditional (longitudinal) standards of maternal weight are needed.

Objective: This study aimed to develop and validate unconditional and conditional maternal weight standards for use in Malawi, Africa.

Design: Longitudinal data were drawn from an antenatal care intervention study conducted in Malawi. Participants were selected for this analysis if they had a healthy profile defined by body mass index and infectious disease measures and delivered healthy singletons defined by birth weight, gestational age, and neonatal survival status. A total of 1733 measurements from 358 women were randomly split to form development and validation samples.

Results: Unconditional and conditional standards were developed and validated. An electronic spreadsheet implements the calculations. Weight gain during pregnancy was substantially slower in this cohort than the US Institute of Medicine recommendation. The percentiles increased linearly; therefore, the use of the conditional standards is robust to inaccuracy in gestational age estimates.

Conclusion: The standards can facilitate researchers and clinicians to examine maternal weight and weight gain and estimate their associations with pregnancy outcomes in Malawi. This trial was registered at www.clinicaltrials.gov as NCT00131235.