The role of progesterone in preterm delivery

The hormone progesterone:

Progesterone, also called the corpus luteum hormone as the most important representative of pregnancy hormones, has a natural occurrence in the body. In the woman's body, this hormone regulates the menstrual cycle, the receptivity of the endometrium, the implantation of the embryo and the successful occurrence of pregnancy. In the latter half of the menstrual cycle, also called the luteal phase, progesterone is secreted by the corpus luteum. This corpus luteum develops from the follicles in the ovary after ovulation. If fertilisation occurs, the hormone prevents further follicle maturation. During pregnancy, the hormone is produced in larger quantities by the placenta. In this case, it helps to immobilize the uterus during pregnancy.

In the medical field, progesterone is either administered orally in capsule form or the hormone is applied locally, for example as a cream.

Progesterone in men:

In the male body, progesterone is produced in the testes. However, the task and function of the hormone have not yet been researched in detail. Furthermore, small amounts of progesterone are built up in the adrenal cortex in both women and men.

Possible other functions:

Other functions of the corpus luteum hormone during pregnancy, such as immune system regulation, inhibition of premature milk production in the breasts, and induction of labor are still being debated.

Preterm birth and risk factors:

Preterm birth is defined as a birth which occurs before the completed 37th week of pregnancy. Depending on the country and culture, the limit of viability of a preterm birth is classified differently. Preterm birth is a critical factor in prenatal morbidity and mortality worldwide. According to the guidelines of the Society of Obstetrics and Gynecology in the DACH region, 965,000 premature infants die annually worldwide in the first 28 days and another 125,000 die in the first five years of life as a result.

The risk of premature birth is increased by various factors, such as a shortened cervix, infections or stress.

In a complication-free pregnancy, the cervix shortens towards the end of it as part of the preparation for birth. However, if the cervix shortens earlier (shorter than 25mm before 24 weeks of pregnancy), the cervix may open in the middle of pregnancy, increasing the risk of preterm birth.

Progesterone in shortened cervix:

Especially during the second trimester (i.e., 13th to 27th week of pregnancy), shortening of the cervix is a major risk factor for preterm birth.

The gynaecological societies of the DACH region are of the opinion that a vaginal progesterone supply is helpful in case of an opening of the cervix during pregnancy.

Possible support for premature birth:

A study published in the American Journal of Obstetrics & Gynecology sheds light on whether giving progesterone reduces the risk of preterm birth. Pregnant women with a shortened cervix were divided into a study group (498 women) and control group (476 women). The study group received vaginally administered progesterone and the control group received a placebo. The result shows that vaginal progesterone reduces the risk of preterm birth and improves birth outcomes in single pregnancies in women with shortened cervix in the mid-trimester. No adverse effects on the neurological development of the child were also demonstrated in the age up to two years.