Development and evaluation of percentile distribution of body weight by gestational week as a tool for gestational weight management: A retrospective study based on hospital routine data

Abstract

Objectives This study aimed to construct and validate smoothed gestational weight centile curves based on preconception weight status for Chinese pregnant women. Design A retrospective study based on hospital routine data Setting Hospital prenatal care. Population A cohort of pregnant Chinese women with preconception and gestational body weights without maternal or neonatal complications (sample 1, n=2992), and a non-selective independent sample (sample 2, n=7420), were selected from hospital routine data for curve construction and validation. Study design Smoothed body weight centile curves for each gestational week were constructed using the LMS method in sample 1. Validation in sample 2 included analysis of agreement between predicted weight at the 38th week and observed values using the Bland-Altman Index. Predictions were also compared with international curves. Results Smoothed centile curves of gestational weight for the three preconception body mass index groups showed a similar non-linear increasing trend. The differences between predicted body weights and observed values were 0.66±1.58 kg, 0.14±1.61 kg and -0.54±2.06 kg in the underweight, normal weight and overweight groups, respectively. Bland-Altman Index values were 5.2%, 5.6% and 4.7% in the underweight, normal weight and overweight groups, respectively, with limits of agreement of -2.4∼3.8 kg, -3.0∼3.3 kg and -4.4∼3.4 kg, respectively. These limits of agreement were narrower than those of available international curves. Conclusion Body weight percentiles for gestational weeks 0-42 were proposed for underweight, normal weight or overweight Chinese women. These curves could constitute a useful tool for individualised gestational weight management by predicting body weight at a later gestation phase.