Maternal Thinness and Obesity and Customized Fetal Weight Charts

The aim of the study was to determine if customized fetal growth charts developed excluding obese and underweight mothers (CC(18.5-25)) are better than customized curves (CC) at identifying pregnancies at risk of perinatal morbidity.

Data from 20,331 infants were used to construct CC and from 11,604 for CC(18.5-25), after excluding the cases with abnormal maternal BMI. The 2 models were applied to 27,507 newborns and the perinatal outcomes were compared between large for gestational age (LGA) or small for gestational age (SGA) according to each model. Logistic regression was used to calculate the OR of outcomes by the group, with gestational age (GA) as covariable. The confidence intervals of pH were calculated by analysis of covariance.

The rate of cesarean and cephalopelvic disproportion (CPD) were higher in LGAonly by CC(18.5-25) than in LGAonly by CC. In SGAonly by CC(18.5-25), neonatal intensive care unit (NICU) and perinatal mortality rates were higher than in SGAonly by CC. Adverse outcomes rate was higher in LGAonly by CC(18.5-25) than in LGAonly by CC (21.6%; OR = 1.61, [1.34-193]) vs. (13.5%; OR = 0.84, [0.66-1.07]), and in SGA only by CC(18.5-25) than in SGAonly by CC (9.6%; OR = 1.62, [1.25-2.10] vs. 6.3%; OR = 1.18, [0.85-1.66]).

The use of CC(18.5-25) allows a more accurate identification of LGA and SGA infants at risk of perinatal morbidity than conventional CC. This benefit increase and decrease, respectively, with GA.