Provera (medroxyprogesterone) is indicated in the treatment of Dysfunctional Uterine Bleeding, Endometriosis and Secondary amenorrhoea (i.e. absence of menstruation due to some cause). It is contraindicated in pregnancy. There is a very small risk of malformation (unwanted hair in female foetuses such as hirsutism and uro-genital malformation in male foetuses) based on experimental studies in animals since due to ethical reasons no trial can be conducted in humans. Therefore as an abundant precaution, Provera and similar progestogens should not be taken during pregnancy. The risk is indeed quite small and I should think that no further action is warranted except periodic ultrasound examinations. It is not clear if any pregnancy test (other than ultrasound) was done or not because it should have been positive. In very early pregnancy, ultrasound alone is sometimes false negative.