Effect of an intra-uterine device on conception and ovulation in the Rhesus monkey.

From January 1966 to January 1967 British researchers at the Birmingham University Medical School studied the effects of the IUD ON CONCEPTION AND THE occurrence and timing of ovulation in the adult rhesus monkey. 24 controls and 21 IUD users were regularly mated with 6 males from day 12 (or 10) to day 16 of the menstrual cycle. A total of 18 pregnancies occurred amont 15 control monkeys while none of the IUD monkeys conceived. Throughout the breeding program both groups displayed normal menstrual cycles and laparotomy at the conclusion of the experiment indicated morphologically normal genital tracts in the IUD group. All 6 males sired at least one pregnancy thus demonstrating equal fertility. Autopsy and laparotomy of the ovaries of all femal monkeys between day 11 and day 18 of the menstrual cycle showed the absence of an IUD effect on the occurrence of ovulation. The development of corpora lutea during the first 6 to 7 days after ovulation was found to be similar for both control and IUD monkeys and data correlating the time of ovulation showed almost identical results for both groups. It was concluded that the IUD exerts a contraceptive effect in naturally cyclic rhesus monkeys without any obvious effect on ovarian function.