Youthful infertility balanced by late-blooming ovaries
04 March 2009 by Aria Pearson
Magazine issue 2697.
YOUNG women with fertility problems caused by polycystic ovary syndrome may have reason to take heart. Over a lifetime their chances of having children appear just as good as other women’s, perhaps because egg production increases as they grow older.
About 7 per cent of reproductive-age women have PCOS, which features irregular periods, high levels of male hormones and greater numbers of developing follicles, or cysts, on the surface of their ovaries. In a normal ovary, a few follicles appear each month, one or two of which mature and release an egg; the rest die off. Women with PCOS ovulate less often because their extra follicles interfere with normal hormonal activity and stop follicles maturing past a certain stage. This is how PCOS lowers fertility.
Now it looks like that is not the end of the story. Miriam Hudecova and colleagues at Uppsala University in Sweden interviewed 91 women who were 35 or older and had been diagnosed with PCOS when younger. They found the women had undergone just as many pregnancies and borne as many babies, on average, as PCOS-free women of the same age. Some of the women with PCOS had been treated for infertility, but more than two-thirds had become pregnant without such help.
Hudecova also examined most of the women and found that the ovaries of the older women with PCOS showed signs of being more active, with better hormone levels and more eggs available, than those of control women of the same age (Human Reproduction, DOI: 10.1093/humrep/den482).
“As women with polycystic ovarian syndrome get older the chance of getting pregnant may actually be higher,” says Hudecova.
There may be an explanation for this. As women age, fewer follicles are produced each month, and in most this reduces fertility. With PCOS, however, fewer follicles may have the opposite effect: it may stop the hormonal interference and cause follicles to release eggs normally.
The hypothesis is backed up by other studies that have shown that the menstrual cycles of women with PCOS tend to become more regular as they age (Human Reproduction, vol 15, p 24). Marcelle Cedars, a reproductive endocrinologist at the University of California, San Francisco, points out that it also chimes with a recent finding that hormone treatments can coax immature follicles to produce eggs.
“They might hit their reproductive peak a little bit later than other women,” says Richard Legro, a gynaecologist at Penn State Milton S. Hershey Medical Center in Hershey, Pennsylvania. “When we see more data to that effect we’ll revise what we tell them.”