The corpus luteum, which is what remains of an ovarian follicle after the release of an egg, produces the hormone progesterone. The corpus luteum continues to maintain progesterone levels throughout the first trimester of your pregnancy, after which the placenta takes over.
Discovery
Researchers at the University of Rochester in New York identified progesterone and its importance in maintaining pregnancy in 1928, according to PBS Online.
Importance
Progesterone thickens and nourishes the lining of your uterus for implantation and sustenance of the fertilized egg. It plays a part in the formation of the mucus plug in your cervix to prevent bacteria from entering the womb and potentially harming your baby. Because of its properties as a smooth muscle relaxant, it guards against premature contractions as well. Progesterone also acts as an anti-inflammatory agent, preventing your immune system from rejecting your baby.
Time Frame
When you first become pregnant, your progesterone level is at its lowest point. Day by day, the corpus luteum produces more progesterone to sustain the thickness of your uterine wall and the nutrients available to your baby. Through the first two weeks after conception and as your baby grows, your progesterone level should be in the area of 1 to 1.5 nanograms per milliliter. In the next two weeks, it should rise from 2 to 28 ng/ml. In a healthy pregnancy, progesterone levels at the end of the first trimester can be as high as 47 ng/ml, according to AmazingPregnancy.com.
Negative Effects
The muscle-relaxing properties of progesterone might cause a change in your gastric emptying process. This can cause the constipation and heartburn that pregnant women frequently experience. Babyzone.com says progesterone also can make your skin more oily, affecting your complexion.
Concerns
TheLaborofLove.com, a website devoted to pregnancy and childbirth, warns that after the fourth week, a progesterone level below 10 ng/ml can potentially be a warning of miscarriage because it affects the thickness of your uterine wall and the embryo's ability to implant and be nourished. When progesterone levels wane too much, the uterus sheds its lining. Doctors call this corpus luteum defect or deficiency. Another possible explanation for a low progesterone level is that you've erred in identifying your date of conception, and your pregnancy is not as far along as you think.
