bstet Obstet Gynecol. 2003 Jan;101(1):129-35.
The changing epidemiology of multiple births in the
United States.
Russell RB, Petrini JR, Damus K, Mattison DR, Schwarz RH.
Perinatal Data Center, March of Dimes Birth Defects
Foundation, White Plains, New York 10605, USA. rrussell@marchofdimes.com
Objectives:
To describe changes in the epidemiology of
multiple births in the United States from 1980 to 1999
by race, maternal age, and region; and to examine the
impact of these changes on birth weight-specific infant
mortality rates for singleton and multiple births.
Methods:
Retrospective univariate and multivariable
analyses were conducted using vital statistics data from
the National Center for Health Statistics.
Results:
Between 1980 and 1999, the overall multiple birth ratio
increased 59% (from 19.3 to 30.7 multiple births per
1000 live births, P <.001), with rates among whites
increasing more rapidly than among blacks. Women of
advanced maternal age, especially those aged 30-34,
35-39, and 40-44 experienced the greatest increases
(62%, 81%, and 110%, respectively). Although all regions
of the United States experienced increases in multiple
birth ratios between 1991 and 1999, the Northeast had
the highest twin (33.9 per 1000 live births) and higher
order birth ratios (280.5 per 100,000 live births), even
after adjusting for maternal age and race. Between 1989
and 1999, multiple births experienced greater declines
in infant mortality than singletons in all birth weight
categories. Consequently, very low birth weight and
moderately low birth weight infant mortality rates among
multiples were lower than among singletons.
Conclusion:
It is important to understand the changing epidemiology
of multiple births, especially for women at highest risk
(advanced maternal age, white race, Northeast
residents). The attribution of infertility management
requires further study. The differential birth
weight-specific infant mortality for singletons and
multiples demonstrates the importance of stratifying by
plurality when assessing perinatal outcomes.
