The blood level of hcG in a woman with an ectopic pregnancy usually rises at a slower rate than normal. Typically, hCG levels double about every two days for the first four weeks of a normal pregnancy, then slow to every 31/2 days by six weeks. Those with failing pregnancies will also frequently have a longer doubling time early on or may even show falling hCG concentrations during the doubling period. hCG concentrations will drop rapidly following a miscarriage. If hCG does not fall to undetectable levels, it may indicate remaining hCG-producing tissue that will need to be removed (dilation and curettage – D&C).