Medroxyprogesterone acetate does not perturb the profile of steroid metabolites in urine during pregnancy.

The plasma concentrations of medroxyprogesterone acetate (MPA) in 14 women administered the progestagen for threatened abortion during the first 6 weeks of pregnancy were measured by specific radioimmunoassay. Treatment (52 nmol orally every 6 h) was continued to 18 weeks of gestation. The mean plasma concentration of MPA rose rapidly during day 1 of treatment to 14.1 +/- 1.84 nmol/l. It reached 21.5 +/- 2.3 nmol/l by 7 days and subsequently stabilized at around 26.8 +/- 5.0 nmol/l by the end of week 2. Urinary steroid profiles were determined by gas-liquid chromatography and mass spectrometry for six of the MPA-treated women and compared with those of six untreated women of similar gestational age. No differences were detected between the two groups of women, suggesting that the administration of MPA during pregnancy did not alter qualitatively or quantitatively the metabolism and excretion into urine of progesterone and oestrogens.