The influence of fetal sex on the antenatal diagnosis of small for gestational age

Objective: We evaluated the influence of fetal sex on the antenatal diagnosis and detection of small for gestational age (SGA).Methods: The cohort consisted of unselected singleton pregnancies, undergoing routine biometry and cerebroplacental ratio (CPR) assessment at 36 weeks. Locally fitted equations for centiles and Z scores were used. Ultrasound SGA was defined as estimated fetal weight (EFW)<10th centile, SGA at birth as birthweight (BW)<10th centile adjusted for sex.Results: Among 4112 pregnancies, there were 235 female ultrasound SGA fetuses and 177 male; (odds ratios (OR) 1.502 (1.223-1.845)); the detection rate of SGA at birth was 50.6% and 40.9%, respectively (OR 1.479 (0.980-2.228)). In ultrasound SGA girls the abdominal circumference growth velocity (ACGV) between 20 and 36 weeks was less frequently in the lowest decile (OR 0.490 (0.320-0.750)), with no differences in CPR.Conclusions: Females are more commonly diagnosed as SGA; those diagnosed may be at less risk than males.