Overstimulation of ovaries

Fertility drugs stimulate the ovaries to release more eggs, causing them to swell, bleed and retain fluid, leading in rare cases to heart failure. Carrying multiple foetuses increases the risk of potentially fatal blood clots during pregnancy and delivery, and the children born can require follow-up care for many years.

In Germany doctors are prohibited from using fertility techniques that would produce more than 3 offspring per mother. In the USA, reproductive techniques are unregulated, but there is considerable opposition to the practice of over- stimulating the ovaries and then aborting a number of the unwanted foetuses when fertility drugs succeed.