[Intrauterine growth according to fetal sex and maternal parity].

Influence of fetal sex on intrauterine growth (by birth weight) was studied in 8,533 newborn infants (4,199 females and 4,334 males) without known risk factors. Similar effects of maternal parity were also evaluated in infants of the same cohorts (648 infants from multigestae women were excluded because of antecedent abortion, 3,291 were first born to primigravidae and 4,594 were born to multiparae mothers). Male infants mean birth weights were 180-228 g greater than those of female infants. Male infants weighed 3,340 g +/- 390 (mean +/- SD) and 3,643 g +/- 414 (mean +/- SD) and female babies: 3,210 g +/- 376 and 3,502 g +/- 393 (mean +/- SD) at 38 and 41 weeks of gestational age respectively. Mean birth weights of newborn from multiparae were 85-140 g higher than those from primigravidae. Babies from multiparae weighed 3,337 g +/- 393 (mean +/- SD) and 3,608 g +/- 418 (mean +/- SD) and babies from primigravidae: 3,202 g +/- 372 mean +/- SD) and 3,523 g +/- 384 (mean +/- SD) at 38 and 41 weeks of gestational age in each case. All of these data were statistically different at 38 throughout 41 weeks of gestational age. A correction is suggested for birth weight according to a graph of differences between general mean birth weight and those for multiparae, primigravidae, males and females.