If you have been taking ovulation-inducing agents such as clomiphene citrate (can be clomid or serophene) or human menopausal gonadotrophins (can be pergonal), the most commonly used of these fertility drugs, the risk of a miscarriage increases. It is generally agreed, however, that women with fertility problems have an increased risk of miscarriage to begin with. If you fall into this category, your doctor will follow you very closely in the early stage of pregnancy, by monitoring your hormone levels. Once again, this means that many more early miscarriages are detected and reported. We are not, therefore, sure whether the increased rate reflects a real change in the figures, or whether the simply more data are recorded.

Clomiphine, an antiestrogen chemical (not a hormone), has a miscarriage rate of just under 20percent, and Pergonal has a miscarriage rate of just over 20 percent. No one knows exactly why this is, and these figures, of course, can not be exact. If your prolactin level is high, you might be given a drug called bromocriptine to lower it. The miscarriage rate for this drug is just over 10 percent.

The cause of these miscarriage, however, may be an inadequate corpus luteum function. Pregnancies of women who have previously been infertile, as we have seen, are often supported by progesterone suppositories in the first trimester.