What Is the Relationship between Progesterone and Fertility?

High levels of progesterone and fertility often go together, because progesterone is one of the female hormones necessary for pregnancy. Progesterone levels tend to drop during menstruation and as a woman ages, which is why it is uncommon for women to achieve pregnancy while they are menstruating and as they approach menopause. This hormone is also crucial in sustaining pregnancy, because a lack of progesterone is often responsible for miscarriages. Women who are worried about their levels of progesterone and fertility can seek treatment from a doctor for help getting and staying pregnant.

Progesterone is found in high levels during the luteal phase, which is the time just after ovulation. The reason that progesterone and fertility are so closely related is that this hormone causes the uterine wall to thicken in preparation for pregnancy, allowing an embryo to attach to the uterus after conception. When conception does not occur during a cycle, the progesterone levels drop suddenly, causing the uterine lining to shed during menstruation. In some cases, however, conception does take place, but the progesterone levels drop anyway, despite the presence of an embryo. As the uterine lining sheds, the embryo is also shed from the body in a miscarriage so early that the mother is not even aware she ever conceived, because the menstruation may appear normal to her.

Low progesterone may occasionally occur in some otherwise fertile women and requires no treatment in such cases. Some women never seem to have enough progesterone to stay pregnant, resulting in early miscarriages. Some women with low progesterone have trouble getting pregnant at all. Elevated progesterone increases the libido, and a lack of this hormone can lead to less sexual intercourse, reducing the chances of pregnancy. Problems with progesterone and fertility may result from old age, because this hormone decreases as women approach menopause, but some young women naturally have low levels of the hormone.

After a woman has had trouble getting pregnant for more than a year or has had a few miscarriages, she is often advised to have her progesterone levels tested. In non-pregnant women, the blood test can be given at a few points throughout the menstrual cycle to determine the levels at various times. Those who are worried less about progesterone and fertility and more about their levels of this hormone in early pregnancy can get the test done at any point in the first trimester to find out whether they need to have progesterone supplements to maintain the pregnancy. Progesterone supplements are often given in the form of a pill, cream or injection to increase fertility or sustain a healthy pregnancy.