Risk factors and perinatal outcomes associated with idiopathic small for gestational age Taiwanese newborns

Objective To determine risk factors and perinatal outcomes associated with small for gestational age (SGA) neonates among healthy pregnant women. Methods A retrospective cohort study was conducted of 49 945 women who gave birth at Chang Gung Memorial Hospital, Taipei, Taiwan, after 24 weeks of pregnancy. Idiopathic SGA newborns (n = 3398) were characterized by a birth weight below the 10th percentile for mean weight corrected for GA and fetal sex. Results Risk factors for idiopathic SGA newborns included hypercoiling of the umbilical cord (adjusted odds ratio [aOR], 3.3; 95% confidence interval [CI], 1.6-7.0); prior fetal death (aOR, 2.8; 95% CI, 2.0-3.9); primiparity (aOR, 1.5; 95% CI, 1.4-1.7); adolescent pregnancy (aOR, 1.5; 95% CI, 1.2-2.0), low prepregnancy weight (aOR, 1.6; 95% CI, 1.5-1.8), low prepregnancy body mass index (aOR, 1.1; 95% CI, 1.0-1.3); short stature (aOR, 1.3; 95% CI, 1.1-1.4); and entangled umbilical cord (aOR, 1.1; 95% CI, 1.0-1.3). Idiopathic SGA newborns correlated with increased risk of adverse perinatal outcomes, including fetal death, low Apgar scores, oligohydramnios, placental abruption, and admission to the neonatal intensive care unit. Conclusion Some risk factors for idiopathic SGA newborns were modifiable, suggesting potential implications for public health.