To better understand the role of the ovarian corpus luteum, see this short description of how an egg becomes a fetus "Journey of an Egg - From follicle to uterus"
PROGESTERONE is a steroid hormone vital to the reproduction process. Produced by a corpus luteum in one of the two ovaries during the 2nd half of the menstrual cycle, by a process which breaks down cholesterol molecules. The ovaries take turns each month.
During pregnancy, corpus luteum continues to produce PROGESTERONE until close to the end of the first trimester. At which time the placenta should have taken over production. Normal production of hormones, including PROGESTERONE, is significantly increased during pregnancy, especially by the third trimester.
Insufficient PROGESTERONE during pregnancy can result in:
PROGESTERONE production /availability is crucial for development of the fetus. A sufficiency of PROGESTERONE production by the ovarian granulosa cells of the corpus luteumin the early stages of pregnancy performs several necessary functions (which could be lacking with a luteal phase deficiency (LPD), where the corpus luteum is not producing sufficient PROGESTERONE):
- Prevents mother's immune system from responding to fetal antigens and rejecting the "new arrival". It does this by stimulating secretion of immune system Th2 and reducing secretion of Th1 cytokines.
- Overrides uterine contractions. Controls hypercontractility of smooth muscle cells in the middle layer of the uterine wall (myocytes);
PROGESTERONE therapy/supplementation provides a "tool" to aid conception and maintain a pregnancy in a woman with estrogen dominance or whose corpus luteum is not producing sufficient PROGESTERONE (termed luteal phase deficiency (LPD)). Either during the luteal phase of the menstrual cycle (latter half of cycle in humans) and/or after conception. Supplementing natural PROGESTERONE at the right time and dose can:
Significantly lower levels of PROGESTERONE are found in women with PCOS in the early luteal phase which may contribute to their delay in conception. LPD in PCOS may explain the anovulation and miscarriage that occurs in these women;
Prevent miscarriage during luteal phase of menstrual cycle and after conception. By countering estrogen presence after fertilization. Too much estrogen compared to PROGESTERONE during the luteal phase can cause miscarriage i.e. when follicles ovulate normally, but fail to continue their PROGESTERONE production at levels necessary for successful implantation of the fertilized egg and development of the embryo.
Maintain sufficient PROGESTERONE to maintain pregnancy until placenta takes over production. PROGESTERONE has many necessary roles in pregnancy - from controlling mother's immune response (e.g. preventing untimely contractions) to providing nutrients for growing fetus. The placenta usually takes over the job of producing PROGESTERONE 10 weeks after gestation (which begins Day 1 of last period) - i.e. when fetus is 8 weeks old.
Supplementating PROGESTERONE for Conception / Pregnancy problems related to Luteal Phase Deficiency
The effects of Estrogen during pregnancy are: