Changes
in prenatal care for women pregnant with twins appears to be
contributing to an increase in twin births that are “moderately
preterm,” occurring between 35-36 weeks of pregnancy, according
to a new HRSA study.
HRSA
epidemiologist Michael Kogan, Ph.D., Maternal and Child Health
Bureau, is first author of “A Comparison of Risk Factors for
Twin Preterm Birth in the United States Between 1981-82 and
1996-97,” published in the March issue of the Maternal and
Child Health Journal. The study looked at a variety of factors
that might contribute to preterm births.
Study
findings indicate:
- The overall rate of twin preterm
birth has risen markedly from 1981-82 and 1996-97.
- The rate of twins born before
33 weeks increased only 7 percent between 1981-82 and 1996-97,
while the rate for those born between 33 and 34 weeks increased
31 percent. The rate for twins born between 35 and 36 weeks
(moderately preterm) rose 51 percent over the study
period, while the rate for twins born from 37 to 44 weeks
(term birth) declined 22 percent.
·
The
“intensive” use of prenatal care, marked by an “excessively
large number of prenatal visits,” was much more likely to be
associated with moderately preterm twin births in 1996-97 than
in 1981-82.
·
African
American women, teenagers, unmarried woman, women with low education
and those having their first babies were more likely to deliver
preterm. However,
the effect of these risk factors diminished over the study period.
This
study illustrates that changing clinical practices -- delivering twins earlier -- may have unintended effects
on the public health goal to reduce preterm and low birth weight
rates in the United States. In general, twin pregnancies and
preterm births, where babies are smaller, do pose greater risks
to babies’ health than single births delivered at term.
For
an abstract of the article, go to the
Journal's
web site and click on Journal Contents, then
Issue 1. More information on HRSA's Maternal
and Child Health Bureau also is available online.
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