Sex differences in fetal growth responses to maternal height and weight.
Sex differences in fetal growth have been reported, but how this happens remains to be described. It is unknown if fetal growth rates, a reflection of genetic and environmental factors, express sexually dimorphic sensitivity to the mother herself. This analysis investigated homogeneity of male and female growth responses to maternal height and weight. The study sample included 3,495 uncomplicated singleton pregnancies followed longitudinally. Analytic models regressed fetal and neonatal weight on tertiles of maternal height and weight, and modification by sex was investigated (n = 1,814 males, n = 1,681 females) with birth gestational age, maternal parity, and smoking as covariates. Sex modified the effects of maternal height and weight on fetal growth rates and birth weight. Among boys, tallest maternal height influenced fetal weight growth before 18 gestational weeks of age (P = 0.006), and prepregnancy maternal weight and body mass index subsequently had influence (P < 0.001); this was not found among girls. Additionally, interaction terms between sex, maternal height, and maternal weight identified that males were more sensitive to maternal weight among shorter mothers (P = 0.003) and more responsive to maternal height among lighter mothers (P < or = 0.03), compared to females. Likewise, neonatal birth weight dimorphism varied by maternal phenotype. A male advantage of 60 g occurred among neonates of the shortest and lightest mothers (P = 0.08), compared to 150 and 191 g among short and heavy mothers, and tall and light-weight mothers, respectively (P = 0.01). Sex differences in response to maternal size are under-appreciated sources of variation in fetal growth studies and may reflect differential growth strategies.
Lampl
Michelle
M
Department of Anthropology, Emory University, Atlanta, Georgia, USA. mlampl@emory.edu
Gotsch
Francesca
F
Kusanovic
Juan Pedro
JP
Gomez
Ricardo
R
Nien
Jyh Kae
JK
Frongillo
Edward A
EA
Romero
Roberto
R
D001724:Birth Weight; D001827:Body Height; D001835:Body Weight; D005260:Female; D047109:Fetal Development; D020567:Fetal Weight; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D033261:Maternal-Fetal Relations; D010298:Parity; D011247:Pregnancy; D012737:Sex Factors; D012907:Smoking; D015430:Weight Gain