Hi & Welcome to HCM. Norethisterone has been assigned to pregnancy category X by the FDA which means animal studies have not been reported, however human pregnancy data have revealed a possible association between first trimester progestin use and genitourinary anomalies in male and female fetuses. It also increases chances of first trimester abortion. So, stop taking Norethisterone & inform your doctor immediately. Have a proper rest & visit the ER if you feel any cramping pain or bleeding vaginally & get an ultrasound done for well being of fetus about 6-8 weeks later and take iron and folic acid tablets as prescribed by your doctor. Hope this will help.