Home fertility tests may not be reliable predictors of a woman's ability to get pregnant, researchers at the University of North Carolina-Chapel Hill have found.
The group, led by Dr. Anne Z. Steiner, an assistant professor of obstetrics and gynecology, found the do-it-yourself kits often indicated women would have difficulties, yet many had no problem conceiving.
"Although the tests are out there, this is the first study that asks, can these tests be used to measure potential fertility?" Steiner said.
Women typically use the tests to gauge their chances of becoming pregnant, particularly if they've postponed child-bearing into their 30s when fertility diminishes. For years, women in the U.S. have delayed their first pregnancies, on average now until age 25; in the 1970s, the average age was 21.
At about age 30, fertility gradually starts to wane as the number and quality of eggs declines. The drop-off is steeper in a woman's late 30s.
Like a pregnancy test, a home fertility detector uses a chemically treated strip that reacts to hormones in the urine and displays a reading.
Readings above a certain level are supposed to signal a woman may be infertile.
But Steiner's group found abnormal FSH levels did not correlate to reduced fertility among the women who participated in the study.
Although FSH levels were not good predictors of who would have difficulty conceiving, another hormone was more accurate. That chemical, anti-mullerian hormone, is produced in the ovaries and also controls the growth of egg follicles. Steiner said screenings might need to include more than one hormone.
although AMH can only be measured in blood.
"When we have larger numbers of women in the study, we will be able to look at how many women conceived in a year despite an abnormal test value," Steiner said.
Her findings result from a small trial of about 100 women in the Raleigh-Durham, N.C., area who were older than 30. The women, who were all trying to become pregnant and had no history of infertility, supplied both blood and urine samples that were tested for FSH and other hormones.
Although FSH levels were not good predictors of who would have difficulty conceiving, another hormone was more accurate. That chemical, anti-mullerian hormone, or AMH, is produced in the ovaries and also controls the growth of egg follicles.
Steiner said screenings might need to include more than one hormone, although AMH can only be measured in blood.
Heather Boles, 32, of Chapel Hill said she volunteered to participate in the study this year when she and her husband, Marty, began trying for their second child. She said her role lasted about two months - when she became pregnant.
"We didn't have any trouble" conceiving, Boles said. She said she wasn't concerned about fading fertility but would have pursued additional measures if months had passed without success.