The pregnancy hormone human chorionic gonadotrophin (hCG) is generated by cells that form in the placenta. Blood tests can often identify hCG by 11 days after fertilisation, and urine tests often pick up the hormone by 12 to 14 days after fertilisation. HCG levels can provide useful information for determining whether a pregnancy is healthy. In approximately 85 per cent of normal pregnancies, hCG levels double every 48 to 72 hours. If you have reason to worry that your pregnancy may not be developing normally, checking your hCG levels can help you identify a problem or, hopefully, provide reassurance.
Take a home pregnancy test (hpt), which detects hCG in your urine. With a highly sensitive test, you can get a positive result as early as seven days after conception, but this is uncommon. Test 12 to 14 days after you ovulated to get the most reliable answer as to whether you are pregnant. If the test turns positive, then you have hCG in your urine and are pregnant. While the lines on an hpt tend to get darker as your pregnancy progresses, the test can only tell you whether you have hCG in your system. The darkness of the line isn't a reliable indicator of your hCG levels.
Call your doctor or midwife to request a quantitative hCG test, also called a beta hCG test, which measures the amount of hCG in your system. Doctors don't routinely check hCG levels during pregnancy but may agree to do so if you have a history of pregnancy problems, such as miscarriage or infertility, if you are bleeding or if you simply feel anxious about whether your pregnancy is developing normally. Explain your reasons for wanting your hCG levels tested and, if you have an understanding caregiver, he will hopefully agree to your request.
Visit the laboratory your caregiver recommends, once you have her orders for the hCG test, to have your blood drawn. A beta hCG test measures the exact amount of hCG in your blood. A number below 5 indicates you aren't pregnant. A number over 25 is a positive pregnancy result.
Repeat the beta hCG test 48 hours after your first test. The normal ranges for betas vary greatly during pregnancy, so a single test won't tell you very much about whether your pregnancy is viable. If your hCG levels have a doubling rate between 48 and 72 hours, it indicates that your pregnancy is developing normally. However, even if you have a slower double rating, it doesn't necessarily mean anything is wrong. Fifteen per cent of normal pregnancies do not double within 48 to 72 hours.
Check your hCG levels a third or fourth time if your doctor or midwife recommends continued testing. HCG levels that rise slowly sometimes indicate a miscarriage or ectopic pregnancy, so if your levels fall outside the normal range, your caregiver may want to continue monitoring you until you reach approximately 6 weeks. At that time, an ultrasound can determine whether your baby has a heartbeat.
Tests of hCG levels are usually very accurate. However, if you were treated with a fertility medication that includes hCG, you might get a false positive if you start testing earlier than 14 days after ovulation.