Customized birth weight: coefficients and validation of models in a UK population.

OBJECTIVES To produce a customized birth weight model in a UK population. METHODS This was a population-based, multiethnic, retrospective cohort study of 42,583 women with uncomplicated singleton pregnancies resulting in a live birth at 37-42 weeks of gestation between 1997 and 2005. Multivariate analysis was undertaken and a double cross-over approach was employed to validate the models estimating customized birth weight. RESULTS Coefficients confirmed the findings of previous studies, indicating that birth weight was strongly influenced by maternal ethnicity, age, parity, body mass index, smoking, fetal gender and gestational age at delivery. CONCLUSIONS We have derived models to determine customized or predicted birth weight in a UK population that are both robust and reproducible.