Infertility Treatments May Raise Birth Defect Risk
Study Finds Certain Kinds of Assisted Reproduction Are Linked to Higher Rates of Birth Defects
WebMD News Archive
Freezing Embryos May Lower Birth Defect Risk continued...
"The freeze-thaw cycle improves risk," Davies says. "The birth weights and gestations also improve after freezing."
That may be because embryos that survive freezing are simply healthier to begin with and more likely to develop normally, he says.
"I think it's probably an [indicator] of embryo quality," Davies tells WebMD. "There's quite a loss of embryos during the freeze-thaw cycle. What's interesting is that it may be the ones that are not developmentally competent anyway."
Other treatments associated with higher risks of birth defects included gamete intrafallopian transfer (GIFT), which involves mixing an egg and sperm in a test tube and then immediately placing the mixture into a fallopian tube. GIFT was tied to a 73% increased risk of birth defects, but experts say it is less of a concern because it's rarely used anymore.
Researchers Warn Against Self-Dosing Clomid
The highest risk associated with any treatment was seen with the at-home use of the drug clomiphene citrate, or Clomid, which stimulates ovulation.
Fertility doctors know to carefully time the dosing of Clomid so that it stimulates ovulation but is cleared from the body before a woman becomes pregnant.
"It's not a drug that a fetus wants to be exposed to," says Davies. "It stops the growth of new blood vessels, but that's not necessarily what we want to happen in a developing fetus."
The FDA has labeled Clomid as a drug that should not be used in pregnancy because it raises the risk of major birth defects.
Women who are desperate to become pregnant, but who may not be able to afford the expense of fertility treatments, sometimes order Clomid off the Internet, Davies says.
Women in the study who opted to use Clomid on their own, without medical supervision, had a 300% higher risk of having a baby born with a birth defect compared to fertile couples.
"I actually think we may be seeing the tip of the iceberg in that finding, to be quite honest. I think it may help contribute to why we're seeing an excess of birth defects in women who went through infertility but who don't report ART," Davies says. He is planning more research to look into the problem.