How often does human chorionic gonadotropin (hCG) double?

In the early stages of pregnancy, human chorionic gonadotropin (hCG) levels typically double every 1.7 to 2 days. Around weeks 8 to 10 of pregnancy, hCG levels reach their peak, after which they rapidly decline.

Human chorionic gonadotropin is a glycoprotein secreted by the trophoblastic cells of the placenta and consists of alpha and beta subunits. After implantation of the fertilized egg, hCG levels in the pregnant woman begin to rise significantly. The rate of hCG increase differs between intrauterine and ectopic pregnancies. In normal intrauterine pregnancies, hCG levels rise more rapidly, increasing by over 60% within 24 hours and showing a doubling trend every 1.7 to 2 days.

Doubling of hCG levels every other day during early pregnancy is a normal phenomenon, indicating healthy fetal development within the uterine cavity. However, if hCG levels fail to double or remain consistently low, an ectopic pregnancy should be suspected. Further diagnostic evaluation and appropriate treatment measures are necessary in such cases.