If you're pregnant, one of the things your doctor will likely test for in the early weeks of your pregnancy is your progesterone level. This is because if you have low progesterone, it can be quite difficult to maintain a pregnancy. It's possible to keep a pregnancy even with low progesterone, with proper medical care.
Progesterone
The progesterone hormone has an important role in early pregnancy --- it helps ensure that you don't menstruate. The purpose of progesterone both during your normal reproductive cycle and during pregnancy is to proliferate and maintain the uterine lining, explains Dr. Lauralee Sherwood in her book "Human Physiology." If you're pregnant, a developing embryo embeds in the uterine lining and extracts all its nutrition from the blood vessels of the lining until such time as the placenta finishes developing, which takes place around the third or fourth gestational month.
Progesterone Levels
Normally, your progesterone levels rises for about 14 days following ovulation, and then begins to fall. If you become pregnant, the developing fertilized egg secretes a hormone called hCG, or human chorionic gonadotropin. The purpose of this hormone is to communicate to your body that you're pregnant, which causes tissue in your ovaries to continue secreting progesterone. This maintains the lining of the uterus, which would normally be sloughing --- causing you to menstruate --- right around the time the fertilized egg implants in the uterine lining.
Low Progesterone
To maintain a healthy pregnancy, you need to have adequate blood levels of progesterone. The Advanced Fertility Center of Chicago explains that if your progesterone levels are below 15 ng/mL, it's possible that something might be wrong with the pregnancy. It's also possible that you could have a completely normal pregnancy, but be producing low levels of progesterone for some other reason. Physicians typically test progesterone between weeks four and six of pregnancy.
Causes
Among the most likely causes of low progesterone in an abnormal pregnancy is ectopic implantation, in which the fertilized egg implants outside the uterus. Ectopic pregnancies typically show low levels of hCG production, resulting in low levels of progesterone production, though this is not always the case. Unfortunately, these pregnancies aren't viable, and must be terminated. In some cases, you may have a completely normal pregnancy despite a low progesterone level. This could be due to low progesterone production by the corpus luteum, an area of specialized ovarian tissue.
Treatment
If your doctor determines that you have low progesterone despite an otherwise normal, uterine pregnancy, you'll probably receive supplemental progesterone for the first weeks and months of your pregnancy. You'll likely take the supplemental hormone in the form of a pill, though it's also possible to receive hormone injections. Typically, by the fourth month of pregnancy, low progesterone is no longer an issue, as the placenta has developed by that time. Dr. Miriam Stoppard, in her book "Conception, Pregnancy and Birth," explains that the placenta also secretes progesterone, typically in high levels.
References
- "Human Physiology"; Lauralee Sherwood, Ph.D.; 2004
- Advanced Fertility Center of Chicago: Progesterone Levels
- "Conception, Pregnancy and Birth"; Miriam Stoppard, M.D.; 2008
