The hormone hCG or Human chorionic gonadotropin, is produced in a woman’s body once she is pregnant. Post implantation, this pregnancy hormone is produced by the placenta in around a week of the fertilization and ovulation. It is responsible for nourishing the fertilized egg that is attached to the uterine wall.
Once a woman is pregnant, the hCG levels can be detected by blood tests after about eight to eleven days of being pregnant. Urine tests can detect the hCG levels in around twelve to fourteen days of the pregnancy. The unit for measuring hCG hormone is milli-international units per milliliter (mIU/ml). A blood serum test showing hCG levels of 25 mIU/ml (25 IU/L) indicates a positive pregnancy while levels less than 5 mIU/ml (5 IU/L) shows a negative pregnancy test.
It is in the early stages of pregnancy that the hCG levels continue to rise. In fact every 48 to 72 hours the hCG levels will double itself. As you progress farther into the pregnancy the rate of increase will slow down significantly and the time taken to double the hCG levels can increase to more than 96 hours.
According to the American Association of Pregnancy the normal hCG levels at around three weeks will be around 5 – 50 mIU/ml which in turn can increase to 5 – 426 mIU/ml in the 4th week. By the sixth week the hCG levels would have increased dramatically to 1,080 – 56,500 mIU/ml.
By seven to eight weeks hCG levls would be around 7, 650 – 229,000 mIU/ml. The rate now keeps on decreasing significantly with women in the last few weeks of pregnancy having hCG levels of 3,640 – 117,000 mIU/ml. These hCG levels are calculated based on the last menstrual period. When the levels are approximately 2000, an ultrasound can detect the fetus.
As you can see the normal hCG levels in early pregnancy can vary widely at any given time of the pregnancy. However in the majority of the cases low hCG levels in pregnancy indicate a possibility of a miscarriage or an ectopic pregnancy while high levels may indicate twin pregnancy, molar pregnancy or a miscalculated conception date.
Certain fertility drugs can interfere with the normal hCG levels in early pregnancy. If the doctor believes that there is a risk to the pregnancy then the hCG levels are monitored every 72 hours