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Richard Scott, the former director of a respected IVF program at St. Barnabas Hospital in Livingston, N.J., has doubts as well. The CDC study, he notes, found lower birth weight in single pregnancies only, not multiple ones. "If technologies were somehow 'changing the fetus,'" he reasons, "you'd think there would be an amplified effect on twins and triplets. But there wasn't." Moreover, earlier research in the U.S., Belgium and Israel found no such effects. Scott does take the new research seriously. But, he says, "this one study does not undermine all the previous work."
Some of the same caveats apply to the birth-defects study, say experts. Here, too, earlier research had found no significant differences between test-tube babies and conventionally conceived kids. And here, again, the new study didn't correct for the fact that women who get reproductive assistance often have something wrong with their reproductive system in the first place.
Dr. David Adamson, a Stanford professor, fertility expert and the director of Fertility Physicians of Northern California, is reminded of a celebrated 1992 Stanford study suggesting that fertility drugs might raise the risk of ovarian cancer. Later research cast doubt on that finding--but only after thousands of women were terrified. "It does not do the country a service," he says, "to present this out of perspective."
Even if these new studies are borne out by later research--already under way in infertility programs in Australia and the U.S.--the risks to kids conceived by assisted reproduction remain reassuringly small. And even if the danger is twice what doctors previously believed, 91% of ART babies would still be born perfectly healthy. Says Dr. Zev Rosenwaks, director of New York Presbyterian Hospital's infertility program: "If you ask a couple if they would rather not have a child at all or try to have a child that over 90% of the time will be normal, I think they will choose to have the child."
No doubt about it, agrees Pamela Madsen, executive director of the nonprofit American Infertility Association: "Infertile people want the joy of a biological child. If you tell us we have to be careful--in fact, if you tell us we have to stand on our head for nine months--we'll do it."
--Reported by Janice M. Horowitz, Alice Park and Sora Song/New York