Maternal Thinness and Obesity and Customized Fetal Weight Charts

Objective: 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. Material and Methods: 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. Results: The rate of cesarean and cephalopelvic disproportion (CPD) were higher in LGA only by CC (18.5−25) than in LGA only by CC . In SGA only by CC (18.5−25) , neonatal intensive care unit (NICU) and perinatal mortality rates were higher than in SGA only by CC . Adverse outcomes rate was higher in LGA only by CC (18.5−25) than in LGA only 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 SGA only by CC (9.6%; OR = 1.62, [1.25–2.10] vs. 6.3%; OR = 1.18, [0.85–1.66]). Conclusion: 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.