Sept. 13, 2002 -- Women who have delayed having children may find welcome relief in the results of a new study. It shows that twins and triplets born to older moms don't face any more risks than those born to younger women. In fact, triplets born to older moms may even fare better.
The number of births to older women has been growing rapidly in recent years. According to researchers, 13% of all births in the U.S. now occur in women over the age of 35.
And the number of twins born to moms over 35 has increased 5.6-fold from 1980 to 1999, while the number of triplets soared 31-fold. Researchers estimate that about 80% of those multiple births are attributable to the use of assisted-fertility technology.
Although pregnancies involving twins and triplets are riskier than single pregnancies at any age, researchers say the greater risks faced by infants born to older women may be offset by other factors.
For example, many mothers who are pregnant with more than one baby conceive them through assisted-fertility techniques such as in vitro fertilization, in which the eggs are fertilized in a laboratory. Researchers say twins and triplets conceived in this manner are less likely to be identical. Non-identical multiples have a lower risk of complications at birth than do identical siblings.
In addition, mothers who conceive through assisted fertility are monitored more closely throughout the pregnancy and tend to receive better prenatal care than mothers who conceive multiples naturally.
In the study, researchers at the National Institute of Child Health and Human Development (NICHD) and the University of Kansas analyzed information on more than 147,000 twin pregnancies and more than 5,000 triplet pregnancies that occurred between 1995 and 1997 in the U.S. They also looked at federal data on more than 3 million single pregnancies in 1996.
The study appears in the September issue of Fertility and Sterility.
The researchers found that among single births, the likelihood of suffering from problems, such as very preterm birth, very low birthweight, or miscarriage or death within one year of birth, increased as the age of the mother increased.
But this relationship between increasing age and increased risk to the baby nearly disappeared among twin births. And triplets born to older mothers were actually more likely to fare better than those born to younger mothers.
Multiple pregnancies are riskier than single pregnancies at any age and under any care, says researcher Jun Zhang, MD, PhD, of NICHD, in a news release. But this study shows us that the right medical care can make multiple pregnancies safer, Zhang says.