Minimal stimulation IVF with Clomid is less effective than standard in vitro fertilization
Clomid is an oral medication that has been used for over 40 years in women with infertility. Clomid stimulates the pituitary gland to trigger stimulation of the ovaries. The result is the growth and development of a few eggs. When the ovaries are stimulated, at a certain point the pituitary gland will trigger ovulation. In order to perform IVF, this signal from the pituitary gland must be blocked or at least controlled. Otherwise, many IVF cycles would be cancelled. A group of medications known as GnRH antagonists may be used to prevent ovulation.
A few small studies have been published using clomiphene citrate for in vitro fertilization. One study, published in 2003, evaluated 33 infertile couples who used clomid and compared them to 156 couples who went through standard in vitro fertilization. The group that used clomiphene citrate ended up with fewer eggs, less embryos, less embryos transferred and less embryos that could be frozen. The pregnancy rate was less than one-half of the pregnancy rate of the standard in vitro fertilization group. This was due to a much lower implantation rate. In other words, the number of pregnancies produced per embryo transferred was much lower.
The authors suggested that the lower rate of implantation and pregnancy rate might have been due to adverse effects of the clomiphene citrate on the uterine lining rather than an effect of the embryos themselves.
Although each clomiphene citrate cycle was less expensive to perform, the couples would be predicted to spend more money overall because they would require a greater number of attempts to get the same number of pregnancies.