Pregnancy loss is when pregnancy becomes non viable and ends up with spontaneous abortion. The urine tests come to be positive and after about 5 weeks one should be able see gestational sac on sonography. At around 6-7 weeks a small foetal pole appears with a cardiac activity. If that doesn’t come up at that time or even later at around 8 weeks or so or if its comes up at 6-7 weeks and then disappears at around 8-10 weeks, then these pregnancies are known as non-viable gestation and they end up.