[Increase in twin maternities and consequences on health].
OBJECTIVE
To describe trends in twin maternity rates, factors which contribute to these trends, and risks associated with twin maternities for mothers and children.


METHODS
The review was done on population-based studies, preferably in France and the European Union.


RESULTS
The rate of twin maternities was 15.6 p 1000 in 2008 and it increased by about 80% between 1972 and 2006. This rise was explained mainly by advanced maternal age and the diffusion of fertility treatments. The major risks for twins were fetal and infant mortality, preterm delivery, small for gestational age, and cerebral palsy. The rate of preterm delivery (<37 weeks) was 44.3% in France in 2003, and the relative risk was 8.8 (95% CI: 7.8-10.0), when compared with single pregnancies. Maternal age and fertility treatments do not change very much the perinatal risk of twins.


CONCLUSIONS
Twin pregnancies are a high risk group which needs more intensive medical care than single pregnancies. The perinatal information system should be improved in France to monitor perinatal indicators according to the number of fetuses in a proper way.
Blondel
B
B
INSERM U953, Unité de recherche épidémiologique sur la santé périnatale et la santé des femmes et des enfants, 94805 Villejuif cedex, France. beatrice.blondel@inserm.fr
D004200:Diseases in Twins / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D005260:Female; D005315:Fetal Diseases / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D006801:Humans; D007231:Infant, Newborn; D017410:Practice Guidelines as Topic; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D059285:Pregnancy, Twin / Q000706:statistics & numerical data*; D012307:Risk Factors