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Defects Moms Have Well-Formed Kids

April 8, 1999

Women with birth defects have normal babies a surprisingly high 96 percent of the time, Norwegian researchers reported today in the New England Journal of Medicine.

Since many birth defects are at least partly genetic, researchers expected to find more of them among babies whose mothers had defects.

Instead, they found that birth defects were seen in 3.8 percent of babies whose mothers had birth defects vs. 2.4 percent of those born to normal mothers.

``It’s not the usual finding of everything looks dark for that family,″ said researcher Rolv Skjaerven of the University of Bergen.

The findings are reassuring and fill a major gap in knowledge for experts who counsel couples on genetic risks, said Dr. Donald Mattison of Chicago, medical director for the March of Dimes.

``While there is an increased risk, it’s at a level many people might feel comfortable with _ not a huge risk overall,″ he said.

The study looked at survival and childbearing rates for nearly 460,000 females born between 1967 and 1982 in Norway, which maintains a national registry that lists birth defects found in the baby’s first five days.

The findings mean that mothers with birth defects are 60 percent more likely than other women to have children with birth defects. But the overall risk of children with birth defects is very small to begin with.

When there are defects, they are often the same ones that the mothers have, the study found.

More than half of the 1,100 mothers with birth defects had relatively minor ones, such as a clubfoot or a cleft lip or palate. Females with severe defects often do not make it to adulthood, and those who are survive are less likely than other women to have children.

Skjaerven said he was surprised that the figures were so low. A 1994 study found that if one child in a family had a birth defect, the next baby was 7.6 times more likely than normal to have the same defect, and 1.5 times as likely to have other problems.

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