Fertility control with sub-dermal silastic capsules containing a new progestin (ST-1435).

The contraceptive action of silastic implants containing a new progestion ST-1435 was investigated in 285 women of reproductive age. A group of 52 women (group A) received three capsules containing each 35 mg of the steroid. A second group of 48 women (group B) received four capsules and a third and larger group of 185 women (group C) received five capsules. No pregnancies occurred during 530 months of use in group A. In 502 months of use recorded for group B, one pregnancy occurred. In group C, 2.142 months were recorded. One pregnancy was reported at the end of 11 months of use and another at the end of 19 months of use. Alterations in the pattern of menstrual bleeding was the most common side effect.