Pregnancy rates increased from 30 percent to a surprising 52 percent when the Jones Institute for Reproductive Medicine at Eastern Virginia Medical School added air filters to their embryo incubators.
The air filters began selling about three years ago, but many fertility clinics were skeptical. Now, fertility specialists are armed with the first scientific proof that incubator filters can help.
"We're not using them but we will be," Dr. Steve Voelkel of Emory University said after reviewing the study. "Anybody who could increase their pregnancy rate from 30 percent to 52 percent would be thrilled. It would have a huge impact on patient care."
Infertility affects as many as one in every five U.S. couples. Thousands turn to in vitro fertilization, where eggs are fertilized in a laboratory dish and grown in an incubator for several days before being implanted into the woman's uterus.
How likely a woman is to become pregnant after the procedure varies from clinic to clinic, but success rates in the 30 percent range are common.
A few years ago, Gen X International of Madison, Conn., began selling filters that promised to keep certain polluting gases out of embryo incubators. The theory was that tiny amounts of "volatile organic compounds" that would never harm a fetus inside a mother's uterus might seep inside a lab's incubators and prove toxic to a microscopic embryo just lying in a dish.
Dr. Jacob Mayer, the Jones Institute's embryology lab director was extremely skeptical that air filters would have any effect, since the lab's air was already controlled under tight regulations.
But the Jones Institute purchased four of the $2,400 incubator filters, enough for half of its embryo incubators, and Mayer set out to resolve the issue.
Between October 1998 and March of this year, he housed embryos in either filtered or unfiltered incubators, randomly assigning them to each incubator. No other part of the IVF treatment changed, and neither the women nor their physicians knew who received "filtered" or "nonfiltered" embryos.
Fifty-two percent of women implanted with embryos grown in filtered incubators became pregnant, vs. 30 percent of women whose embryos were grown in nonfiltered incubators, Mayer reported Tuesday at a meeting of the American Society for Reproductive Medicine.
Mayer doesn't know why the results turned out as they did. Because he didn't expect the experiment to work, Mayer didn't take the expensive step of having his incubators' air quality tested before and after filtration -- so he doesn't know if there were some polluting gas lurking around.
It is too soon to know how many of the Jones Institute's pregnancies culminated in live births, but Mayer will check whether the filters made an enduring difference. Regardless, he has purchased filters for th rest of the clinic's incubators.
A few other clinics have tried the filters and reported they didn't seem to help, but the Jones Institute so far has performed the only scientifically well-controlled study, said Michael Tucker, scientific director of the Shady Grove Fertility Center in Rockville, Md.
"It is a definite step forward," Tucker said. "It has sparked a lot of interest."
Written By Lauran Neergaard