Contrary to popular belief, using birth-control pills for many years does not impair a woman's ability to conceive—in fact, it may enhance it

The Economist, 10 October 2002

USERS of contraceptive pills have had to put up with a lot of worries over the years—deep-vein thrombosis scares, unwanted weight gain and migraine headaches, to name just a few. Women who stop taking the Pill are often advised to “detox” themselves for a few months before trying to conceive. They are further warned that getting pregnant may be harder than it would have been had they never taken chemical contraceptives.

Not so, suggests a study just published in Human Reproduction. Alexandra Farrow, an epidemiologist at Brunel University, in London, and her colleagues, looked at planned pregnancies in 8,497 couples. The couples were asked to fill in a questionnaire that inquired about such matters as age, drinking and smoking habits, Pill use and how long it took to get pregnant.

It turned out that, far from being less fertile than normal, women who had taken the Pill for at least five years were more likely than non-Pill users to conceive within 12 months of starting to try. Some 90% succeeded, as opposed to 85% of those who had not taken the Pill. In fact, the longer a woman had taken contraceptive pills, the more likely she was to conceive quickly, even after other factors were taken into account.

These findings support the idea that the Pill keeps a woman's ovaries young. Chris Ford of the University of Bristol, one of Dr Farrow's co-authors, speculates that by preventing ovulation and the stresses that it puts on the reproductive system, Pill-using women may, in effect, be cheating time. Pill use may also maintain a woman's limited store of eggs, which some people think are ovulated in order, from best to worst.

The researchers cite work carried out a few years ago in Australia. This found that women who had taken the Pill for years were less likely to suffer age-related miscarriages, which are usually caused by bad eggs. Pill-using women over the age of 30 cut their risk of miscarriage from 28% to 7%, according to that study. The next phase will attempt to find out if prolonged Pill use pushes back the menopause, as this theory suggests it should.

All of which is an amusing twist to a tale that began in the 1950s, when a gynaecologist called John Rock first administered oestrogen and progesterone—the main components of the Pill—to a group of women. Rock's goal was not contraception, but conception. His patients were having trouble conceiving, and he reckoned that their ovaries might do better after a short break from ovulating. He appeared to be right. But the preparation he was using was then reformulated as the birth-control pill. What goes around, it seems, comes around—eventually.