Comparison of three different methods across different levels of maternal prepregnancy weight for birthweight at 37–42 weeks in the NICHD Fetal Growth Studies–Singletons (N = 2,288).
REGRESSION
Note: All calculations were performed in SAS with non-rounded numbers. Proc GLM was used for the Gardosi based models, Proc AUTOREG was used for the heteroscedastic models and Proc QUANTREG was used for the quantile regression model. The percentiles were calculated per the equations in epsi_het25 = 374.5975 *exp(0.5*(0.0145*(-7.301)-0.000103*(-7.301*-7.301)-0.0000028*(-7.301*-7.301*-7.301)-0.0123*(0) -0.000357*(0)+0.0000472*(0)-0.003582*(0) -0.000112*(0) -0.000003257*(0)+ 0*(-0.1109)+ 0*(-0.0107)+ 0*(-0.0407)+ 0*(0.0394)+ 0*(0.0403)+ 0.0236*(0)))In both the Gardosi and Heteroscedastic, TOW was specific to each maternal weight percentile. For the quantile regression, the 10