How does HCG promote luteal function?

Generally, HCG refers to human chorionic gonadotropin. It promotes luteal function by simulating the action of luteinizing hormone (LH), maintaining luteal activity, promoting the synthesis and secretion of progesterone and estrogen, prolonging luteal lifespan, ensuring early pregnancy, regulating the secretion balance of luteal-related hormones, exerting immunomodulatory effects, and protecting embryonic development. A detailed analysis is as follows:

1. Mimicking the action of luteinizing hormone (LH) to maintain luteal activity

The β-subunit of HCG is highly homologous to LH and can bind to the LH/hCG receptors on the surface of luteal cells, activating intracellular signaling pathways and mimicking the physiological effects of LH to maintain continuous luteal function. In a normal menstrual cycle, if pregnancy does not occur, the corpus luteum regresses about 14 days after ovulation due to the loss of LH support; however, after conception, HCG secreted by embryonic trophoblast cells replaces LH, stimulating the corpus luteum to continue secreting progesterone and estrogen and preventing its regression.

2. Promoting the synthesis and secretion of progesterone and estrogen

HCG stimulates luteal cells to increase the production of progesterone (progesterone) and estrogen, ensuring the endometrium remains in the secretory phase to provide a stable environment for embryo implantation and early development. Progesterone inhibits uterine contractions, preventing embryo expulsion, while estrogen promotes endometrial thickening and angiogenesis, providing nutritional support for the embryo.

3. Prolonging luteal lifespan and ensuring early pregnancy

Under continuous stimulation by HCG, the corpus luteum transforms from a menstrual corpus luteum into a pregnancy corpus luteum, extending its functional duration to 5-7 weeks of gestation. During this period, progesterone secreted by the pregnancy corpus luteum fully meets the embryo's needs until the placenta establishes its own capacity to secrete progesterone. Insufficient HCG levels may lead to premature luteal regression, increasing the risk of miscarriage.

4. Regulating the secretion balance of luteal-related hormones

HCG not only promotes the secretion of progesterone and estrogen but also regulates the release of luteal inhibin and relaxin. Inhibin suppresses pituitary FSH (follicle-stimulating hormone) secretion, further inhibiting follicular development and ensuring ovarian quiescence during pregnancy, thus preventing interference from new follicle development.

5. Immunomodulatory effects that protect embryonic development

HCG inhibits the maternal immune rejection response against the embryo, reduces the activity of uterine natural killer cells, and lowers the risk of immune attack on the embryo by the maternal immune system. This immunomodulatory effect provides a relatively safe microenvironment for the embryo, ensuring its normal development.

During HCG treatment, patients should follow medical instructions and undergo regular monitoring to evaluate drug effectiveness and promptly adjust treatment plans. Additionally, maintaining a healthy lifestyle and avoiding harmful habits such as smoking and alcohol consumption can help improve treatment success rates.