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Knight Ridder Newspapers
SAN JOSE, Calif. - In what probably will be reassuring to many couples considering fertility treatments, new research suggests that babies conceived with a little help from science are no more likely to have birth defects or chromosomal abnormalities than babies made the old-fashioned way.
But women who become pregnant through in vitro fertilization may experience more complications during their pregnancy, the scientists cautioned. Multiple births are also much more common - and represent the single greatest health risk to babies conceived in that manner.
The findings, however, should help allay previous fears that fertility drugs, IVF and other therapies might be harmful to the babies conceived by them.
"It's a major concern when you're giving drugs," said Dr. Richard Schmidt, medical director of Nova In Vitro Fertilization in Palo Alto, Calif. "It seems to be so foreign. But it's really the exact same hormone that the body uses to get an egg to come out every month, so it would make sense that they would not find anything significant for chromosomal abnormalities."
All in all, "This is good news," said Dr. Tracy Shevell, lead author of the new study, which appears in the November issue of the journal Obstetrics & Gynecology. "The chances of conceiving and having a healthy baby using assisted reproductive technology overall are very high."
The study looked at 36,062 pregnancies in hospitals from Seattle to Ireland. Of that number, 34,286 were unassisted, 1,222 resulted from ovulation induction (i.e., fertility drugs) and 554 were the result of in vitro fertilization.
The risk of multiple births is prompting the American College of Obstetricians and Gynecologists to recommend that couples be counseled about their chances of having multiple babies after turning to fertility treatments, and how that is associated with poor infant outcome, low birth weight and prematurity.
Those risks can be reduced, doctors agree, by limiting the number of fertilized eggs implanted in a woman's uterus through IVF.
"One of the first questions he asked me was how I felt about multiple-birth pregnancy," said Susan Smith, a 28-year-old Castro Valley, Calif., woman who turned to IVF when other therapies failed.
She told Dr. Louis Weckstein that the idea of "selective reduction" - implanting several embryos and eliminating what appear to be the least viable fetuses - troubled her. "We've come so far in this journey of infertility, that how do we decide which fetus you're going to terminate and which one you're going to keep?" said Smith.
"So based on that, they don't transfer more than two embryos" - twins at the most. She and her husband, Jeffrey Smith, are fine with that. She has completed one course of IVF and is beginning a second.
Weckstein, medical director of Reproductive Science Center of the Bay Area, called limiting multiple pregnancies "a very important point. In our center, we've gotten very conservative" - letting the fertilized embryos develop in the laboratory for as long as five days and then choosing "the best of the best, so we can put back fewer. This," he said, "has raised pregnancy rates and cut multiple pregnancy rates.
"That's our goal: healthy babies."
Despite the new study, it remains uncertain whether the fertility treatments are to blame for the slightly increased risk of preeclampsia or placenta abnormalities - or whether underlying medical problems that can make it difficult to conceive in the first place are the true root cause, experts said.
"It should not be surprising that women who had a medical problem that made it difficult for them to get pregnant also had problems once they became pregnant," said Dr. William Gibbons, president of the American Society for Reproductive Medicine, in a written statement.
"The other complicating factor may be age. Women who undergo infertility treatments are often older than most women who become pregnant. Age in and of itself is a risk factor for a more complicated pregnancy."
Weckstein called the study's findings about placenta abnormalities and the risk of high blood pressure "things that we have known and seen for some time," but praised the study for verifying the anecdotal evidence. He called those risks "very slight, really, overall a very small number," and said that in his experience, most patients who suffered from those problems during pregnancy "had normal, successful pregnancies."
For women who require assistance in achieving pregnancy, the message of the study is that it's "very reassuring that there is no increase in birth defects," Weckstein said. "But it's also important that patients be informed and aware that there seems to be some increased risk in some select problems - and they should be followed closely."
(c) 2005, San Jose Mercury News (San Jose, Calif.). Distributed by Knight Ridder/Tribune News Service.