Progesterone in pregnancy

Progesterone in pregnancy-action

Progesterone belongs to the female sex hormones. During the luteal phase of the menstrual cycle, as well as during the first weeks of pregnancy, it is produced by the corpus luteum. Progesterone production depends on stimulation by luteinizing hormone (LH) and chorionic gonadotropin (beta-HCG). It is recognized that by the 7th. Week, the development of pregnancy is entirely dependent on ovarian production of progesterone. In the following weeks, the site that secretes most of the progesterone is the placenta.

Progesterone is responsible for relaxing and reducing smooth muscle tone, thus preventing possible preterm labor. Progesterone also acts on other muscles in a pregnant woman’s body, such as the lower esophageal sphincter (LES). Physiologically, this muscle, being at rest, is constantly tense, so that there is no backflow of food content from the stomach into the esophagus. In turn, high levels of progesterone during pregnancy cause the lower esophageal sphincter to relax, leading to reflux symptoms. In addition, progesterone is also responsible for congestion and distension of the vulva, vaginal walls and cervix. Progesterone also contributes to constipation during pregnancy.

Progesterone in pregnancy-concentration

At the beginning of pregnancy, the corpus luteum produces 25-50 mg of progesterone per day,. The average serum concentration is in the range of 8-48 ng/ml. At the time of delivery, placental progesterone production reaches 250 mg/day, and serum levels are 100-200 ng/ml. In the case of twin pregnancies, progesterone production reaches up to 600 mg/day.  After the birth, at the end of the 1st. postpartum week, progesterone levels reach the pre-pregnancy value. This decrease also allows lactation to begin.

Pregnancy progesterone standards may vary from lab to lab, so reference values for each trimester should be provided on the test result. In turn, the result should always be consulted with a gynecologist.

Too low progesterone in pregnancy

During the menstrual cycle, too low levels of progesterone can cause irregular periods or intermenstrual bleeding. Its deficiency can also make it difficult to get pregnant. This is because progesterone is responsible for, among other things. For preparing the endometrium for nesting. If the level of this hormone is too low, it is much more difficult for the embryo to implant properly, as well as for its early development.

Progesterone and preterm labor

The use of progesterone is listed as one of the methods to prevent preterm labor (along with pessaries and cervical suture). It has a proven effect especially in women who have had preterm labor in the past and in women with a shortened cervix. Progesterone is most often used vaginally. Its effects include. On inhibiting uterine contractility and cervical dilation. It also affects the glands that secrete cervical mucus, which is a barrier to pathogens that can cause an infection that could lead  to preterm labor. 

Bibliography:

 The use of progesterone in the prevention of preterm labor, Gynecology and Practical Perinatology 2018 Vol. 3, No. 3, pages 85-92