Validation of the global reference for fetal weight and birth weight percentiles

Abstract

The objective of this study was to evaluate whether the global reference curves adapted on the basis of WHO data for India and the Hadlock reference curves fi t the population in India and to validate the reference curves. The data were retrieved retrospectively from the records of women registration for antenatal care at a charitable maternity hospital in Mumbai, India. All pregnancies were dated on CRL obtained before 14 weeks. Births before 34th week were excluded. The expected frequencies of birth weights below the 1st, 5th, 10th, 50th, 90th, 95th and 99th centiles from three reference ranges were compared with observed frequencies. It was found that the WHO generic reference adapted to India signifi cantly underpredicted the birth weights and that the Hadlock reference ranges signifi cantly overpredicted the birth weights. The use of generic reference adapted to Sri Lanka showed a better fi t to the observed data. We concluded that global reference curves adapted on the basis of WHO data for India and the Hadlock reference ranges do not fi t all the population in India and the charts need validation. Reference charts modifi ed on the basis of data for Sri Lankan population show a better fi t to the observed data, and therefore are more appropriate for use in clinical practice in South India.