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The Influence of a Male Twin on Birthweight of its Female Co-twin — A Population-based Study

Published online by Cambridge University Press:  21 February 2012

Ran D. Goldman*
Affiliation:
Division of Emergency Medicine,The Hospital for Sick Children,Toronto, Ontario, Canada and Department of Pediatrics, University of Toronto,Toronto, Ontario, Canada. ran.goldman@sickkids.ca
Efrat Blumrozen
Affiliation:
Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, and the Hadassah-Hebrew University School of Medicine, Jerusalem, Israel.
Isaac Blickstein
Affiliation:
Department of Obstetrics and Gynecology, Kaplan Medical Center, Rehovot, and the Hadassah-Hebrew University School of Medicine, Jerusalem, Israel.
*
*Address for correspondence: Ran D. Goldman, MD, Department of Paediatrics, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8 Canada.

Abstract

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Fetal growth is influenced by various determinants, with males being heavier than females. It was recently suggested that female birthweight tends to be increased by the presence of a male co-twin. We evaluated this hypothesis in the Israeli population. We reviewed a retrospective population database of the 1993–1998 Israeli Birth Registry. We compared male birthweight in the male-male and malefemale combination sets and female birthweight in the femalefemale and male-female combination sets. We compared the mean birthweight of males and females in three groups of total twin birthweight. The sample of 12,686 sets included 50.6% males. The male-male combination was found in 31.3% sets, female-female in 38.7% and unlike-sex combination in 30.0%. A total twin birthweight of less than 3000g was found in 7.2% sets, of 3001–5000g in 50.7% sets, and of over 5000g in 42.1% sets. The mean male birthweight was 2398 ± 602 g and the mean female birthweight was 2316 ± 566g, p < .0001 (95% CI of 67, 96). The mean birthweight of males in the malemale combination was significantly lower than in the unlike-sex combination, p < .0001, in total birthweights over 3000g. No significant difference was found between the mean birthweight of females in the female-female and in the unlike-sex combinations in all total birthweight strata. Our findings do not substantiate a male-related inter-twin influence on female birthweight. Population differences might underlie the opposing observations in the literature.

Type
Articles
Copyright
Copyright © Cambridge University Press 2003