W.H.O. Research Team, Chulalongkorn Hospital Medical School, Bangkok, Thailand
The contraceptive steroid, medroxyprogesterone acetate (MPA), which at a dose of 150 mg can be injected every 3 months, is being considered for more widespread use in family planning programmes of developing countries, e.g. Thailand. Since MPA, in contrast to the combined oestrogen-progestagen steroids, does not decrease but may actually increase milk secretion when administered to lactating women (Karim et al., 1971; Koetswang, Chiemprajert & Kochananda, 1972) it could be used more for contraception during lactation.
There is no information on the effects of MPA, when administered to the lactating rat, on the subsequent growth, sexual maturation and reproductive function of the young. MPA may be ingested through the milk, as has been demonstrated for the oestrogen-progestagen steroids (Laumas, Malkani & Laumas, 1971), and affect the release of the gonadotrophic hormones now known to be secreted very early after birth and