As you get further along in pregnancy and the hCG level gets higher, the time it takes to double can increase to about every 96 hours. A normal pregnancy may have low hCG levels and result in a perfectly healthy baby. The results from an ultrasound after 5-6 weeks gestation are much more accurate than using hCG numbers. If cardiac activity is there with good decidual reaction... no need to worry. Consult ur obstetrician to give u hormonal support if required.