i understand your concern. Regesterone (Norethindrone) has been assigned to pregnancy category X by the FDA.Pregnancy Category X means that studies in animals or humans have shown positive evidence of fetal risk, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefits. Postmarketing human pregnancy data have revealed a possible association between first trimester progestin use and genitourinary anomalies in male and female fetuses. Norethindrone use is considered contraindicated during pregnancy. My advice is stop using the medication as soon as the pregnancy test is positive. Talk to your doctor. There is a possibility that it might affect your baby but it also largely depends on the dosage and frequency of drug intake. Take Care!