From the Guidelines
Role of Progesterone in Maintaining Pregnancy
Progesterone plays a crucial role in maintaining pregnancy by preparing the uterus to implant a fertilized egg and supporting the pregnancy throughout its duration [ 1 ].
Key Functions of Progesterone
- Uterine Quiescence: Progesterone helps maintain high uterine quiescence, which is essential for preventing preterm labor [ 1 ].
- Preterm Birth Prevention: Progesterone supplementation, particularly in the form of 17-alpha-hydroxy-progesterone caproate (17OHP-C) or vaginal progesterone, has been shown to prevent preterm birth in women with a history of spontaneous preterm birth [ 2, 3, 4 ].
- Cervical Length Screening: Transvaginal ultrasound (TVU) screening for cervical length can identify women at risk of preterm birth, and progesterone supplementation can be beneficial in preventing preterm birth in these women [ 5 ].
Progesterone Supplementation
Progesterone supplementation can be achieved through medications such as:
- Progesterone capsules (100-200 mg twice daily)
- Injections (50-100 mg per week)
- 17OHP-C (250 mg intramuscularly weekly)
- Vaginal progesterone (90-mg gel or 200-mg suppository daily)
The duration of treatment varies depending on individual circumstances, but it is often continued until the 10th to 12th week of pregnancy, when the placenta takes over progesterone production [ 6, 4 ].
Important Considerations
It is essential to consult a healthcare provider for personalized guidance on progesterone supplementation during pregnancy, as the effectiveness of progesterone supplementation can vary depending on individual circumstances, such as prior preterm birth or cervical length [ 7 ].
From the Research
Role of Progesterone in Pregnancy
- Progesterone is an essential hormone in the process of reproduction, involved in the menstrual cycle, implantation, and maintenance of pregnancy 8, 9, 10, 11, 12
- It plays a crucial role in modulating the maternal immune response and suppressing inflammatory response, reducing uterine contractility, improving utero-placental circulation, and providing luteal phase support 8, 9
Mechanisms of Progesterone in Pregnancy Maintenance
- Progesterone interacts with progesterone receptors at the decidua level, playing a major role in the maternal defense strategy 8
- It promotes the invasion of extravillous trophoblasts to the decidua by inhibiting apoptosis of extravillous trophoblasts, improving utero-placental circulation 8
- Progesterone also acts as an "immunosteroid", contributing to the establishment of a pregnancy protective immune milieu, and upregulates HLA-G gene expression 9
Clinical Applications of Progesterone in Pregnancy
- Progesterone is used in the treatment of threatened miscarriage, recurrent miscarriage, and preterm birth, as well as in assisted reproductive technologies 8, 10, 12
- It has been shown to reduce the risk of miscarriage in women with recurrent or threatened miscarriage, particularly in those with a history of multiple miscarriages 11
- Vaginal micronized progesterone has been found to increase live birth rates in women with a history of miscarriage and current pregnancy bleeding 11