title: Fetal sex and race modify the predictors of fetal growth.
abstract: The objective of this study is unknown if fetal sex and race modify the impact of maternal pre-pregnancy body mass index (BMI), and smoking on fetal growth. The authors studied markers of fetal growth in singleton offspring of 8,801 primiparous, normotensive women, enrolled in the Collaborative Perinatal Project. The authors tested for departures from additivity between sex/race and each predictor. The head-to-chest circumference ratio (HCC) decreased more, while birthweight and ponderal index (PI) increased more for each 1 kg/m(2) increase in pre-pregnancy BMI among term females versus males (P = 0.07, P < 0.01 and P = 0.08, interaction respectively). For term offspring of White compared with Black women, smoking independent of "dose" was associated with larger reductions in growth (165 g vs. 68 g reduction in birthweight, P < 0.01, interaction), greater reduction in fetal placental ratio (P < 0.01, interaction), PI (P < 0.01, interaction), and greater increase in HCC (P = 0.02), respectively. The association of BMI and smoking with fetal size appeared to be reversed in term versus preterm infants. Our study provides evidence that the associations of pre-pregnancy BMI and smoking are not constant across sex and race. This finding may be relevant to sex and race differences in neonatal and long term health outcomes.
authors.affiliation: Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA, simone.reynolds@downstate.edu.
authors.forename: Simone A
authors.initials: SA
authors.lastname: Reynolds
authors.forename: James M
authors.initials: JM
authors.lastname: Roberts
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Bodnar
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Haggerty
authors.forename: Ada O
authors.initials: AO
authors.lastname: Youk
authors.forename: Janet M
authors.initials: JM
authors.lastname: Catov
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D001724:Birth Weight / Q000502:physiology; D015992:Body Mass Index; D005260:Female; D047109:Fetal Development / Q000502:physiology; D005865:Gestational Age; D006801:Humans; D008297:Male; D008423:Maternal Age; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology; D044469:Racial Groups / Q000706:statistics & numerical data*; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects; D012959:Socioeconomic Factors; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult