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Wednesday, 4 January 2012

Twin births rising, especially for older women, CDC says

Wasif Chudhary

More parents are seeing double these days — and federal data released today explains why: The number of twin births in the USA more than doubled from 1980 to 2009.
An analysis of three decades of twin births (2009 data are the most recent year included) finds large increases in twin birth rates for all age groups, among all racial and ethnic groups and in all states and the District of Columbia. The overall U.S. twin birth rate increased 76%, from 18.9 in 1980 to 33.2 per 1,000 births in 2009.
And for mothers age 35 and over, those twin rates have skyrocketed. Among women 35-39, rates rose by nearly 100%, and among those 40 and over, rates rose more than 200%, finds the report from the National Center for Health Statistics, part of the Centers for Disease Control and Prevention.
While the chance of having twins does increase with a mother's age, the report suggests that fertility treatment provides the backdrop for this baby bonus, says CDC statistician Joyce Martin.
"We found that about one-third of the increase over three decades was attributed to older maternal age and two-thirds likely the result of fertility-enhancing therapies — both drugs and technologies like in-vitro fertilization," she says.
As for women in their 20s who had twins, Martin says a small proportion of women in that age group do receive fertility treatment.But Barbara Luke, a professor of obstetrics, gynecology and reproductive biology at Michigan State University in East Lansing, says twins among younger women could be the result of widespread use of the birth control pill.
"Your chance of conception of twins is also higher right after you get off the birth control pill. So that may be why we're seeing it among younger women, since there is more widespread use of birth control pills," she says.
The analysis finds that although the pace of these increases in twin birth rates slowed from 2005 to 2009, twins now make up 3.3% of all births, up from 1.9% in 1980. The number of twin births increased from 68,339 to more than 137,000 in each year between 2006 and 2009.
Robin Gorman Newman, 51, of Great Neck, N.Y., founded the website MotherhoodLater.com after fertility treatments didn't work and she and her husband adopted their son, now 8.
"If someone has become a mom and they're over 40, if they get pregnant au naturel, they're really fortunate. It can absolutely happen, but for many, it takes intervention," she says.
Eric Widra, a Washington fertility specialist with the American Society for Reproductive Medicine, says his group wants to reduce the rate of twin births, which are more dangerous for both moms and babies.
"As pregnancy rates with reproductive technologies have improved, we've been working hard over the past several years to reduce the multiple birth rate," he says. "We can do that by encouraging practitioners to return fewer embryos to the woman's uterus."
Laura Whitlinger of Manhattan, who married at 40 and had "every fertility treatment you could," says she was prepared for multiple births during years of fertility struggles.
"It was like a full-time job getting pregnant," says Whitlinger, 46, the mother of fraternal twins Lyle and Wyatt, now 2½.
Although she had been very healthy, Whitlinger says she had a lot of pregnancy-related complications.
"Bearing twins when over 40 is tremendously hard on the body," she says.
Martin says twins are at higher risk because they are more likely be born earlier and smaller, to require more hospitalization and to die in the first year of life.
That's why the fact that this steady rise has slowed down is "important," she says.

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