Length of gestation and birthweight in dizygotic twins

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Despite the longer gestation of girls, their birthweight is less than that of boys. Because unlike-sex twins provide a natural situation in which to investigate the influence of sex on gestation, we compared birthweight and gestation of 1929 same-sex and unlike-sex dizygotic pairs. Length of gestation in unlike-sex pairs was similar to that of female same-sex pairs, and significantly (0.4 weeks; p=0.02) longer than that of male same-sex pairs. Birthweight of girls from unlike-sex pairs was similar to that of girls from same-sex pairs, but boys from unlike-sex pairs weighed 78 g more than boys from same-sex pairs (p=0.001). These data show that in unlike-sex pairs it is the girl that prolongs gestation for her brother, resulting in a higher birthweight than that of same-sex boys.

Original languageEnglish
JournalLancet
Volume358
Issue number9281
Pages (from-to)560-1
Number of pages2
ISSN0140-6736
DOIs
Publication statusPublished - 18 Aug 2001
Externally publishedYes

    Research areas

  • Analysis of Variance, Belgium, Birth Weight, Female, Gestational Age, Humans, Infant, Newborn, Male, Prospective Studies, Sex Factors, Twins, Dizygotic

ID: 258333255