belongs to category B drug in pregnancy
means animal studies showed no effect on fetus but human studies lacking,
according to FDA, primolut n
belongs to category X means some amount fetal harm is possible,
so as urine pregnancy test kits some times can give false positive results, you wait for blood report then depending on that you discuss with your doctor and follow her advice,
if you want to continue pregnancy follow with careful and regular antenatal checkups to detect any possible anomaly at the earliest.