The impact of the increasing number of multiple births on the rates of preterm birth and low birthweight: an international study.
OBJECTIVE
We studied the effects of twins and triplets on perinatal health indicators in the overall population in the 1980s and 1990s in Canada, England and Wales, France, and the United States.


METHODS
Data were derived mostly from live birth registration. We used rates, relative risks, and population attributable risks for twins and triplets separately.


RESULTS
In each country, the increase in multiple births, and the increase in preterm delivery among multiple births, contributed almost equally to the rise in or stabilization of the overall rates of preterm delivery. Twins contributed a much larger proportion of the preterm deliveries and low-birthweight newborns than did triplets.


CONCLUSIONS
Twins have a major population-based impact on the trends of perinatal health indicators.
Blondel
Béatrice
B
Epidemiological Research Unit on Perinatal Health and Women's Health, National Institute for Health and Medical Research, Villejuif, France. blondel@vjf.inserm.fr
Kogan
Michael D
MD
Alexander
Greg R
GR
Dattani
Nirupa
N
Kramer
Michael S
MS
Macfarlane
Alison
A
Wen
Shi Wu
SW
D002170:Canada / Q000453:epidemiology; D003431:Cross-Cultural Comparison; D004739:England / Q000453:epidemiology; D005260:Female; D005602:France / Q000453:epidemiology; D006306:Health Surveys; D006801:Humans; D015994:Incidence; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007752:Obstetric Labor, Premature / Q000453:epidemiology*; D011247:Pregnancy; D012307:Risk Factors; D014310:Triplets / Q000706:statistics & numerical data*; D014427:Twins / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology; D014852:Wales / Q000453:epidemiology