Genetic influence on prolonged gestation: a population-based Danish twin study.
OBJECTIVE
The purpose of this study was to test a possible genetic component to prolonged gestation.


METHODS
The gestational duration of single, first pregnancies by both female and male twins was obtained by linking the Danish Twin Registry, The Danish Civil Registration System, and the Danish Medical Birth Register. A total of 2588 same-sex twin pairs of whom both cotwins became parents during 1978 to 1996 were identified.


RESULTS
The concordance rate for female twin pairs for a gestation of > or =41 weeks and > or =42 weeks was higher for monozygotic twin pairs than for dizygotic twin pairs, which indicates genetic effects. Biometric modeling suggested that genetic factors account for 23% to 30% of the liability to prolonged gestation. The difference in concordance rate between monozygotic and dizygotic male twin pairs was small, and the best fitting model indicated no genetic factors.


CONCLUSIONS
Maternal genes influence prolonged gestation. However, a substantial paternal genetic influence through the fetus was not found.
Department of Epidemiology, Danish Twin Registry, Institute of Public Health, University of Southern Denmark, Odense, Denmark.
Maja
M
Laursen
Camilla
C
Bille
Annette W
AW
Olesen
Jacob
J
Hjelmborg
Axel
A
Skytthe
Kaare
K
Christensen
D003718:Denmark; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D011273:Pregnancy, Prolonged / Q000235:genetics*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic