Can progesterone prevent or treat spontaneous abortion?

Progesterone is not a "universal solution" for preserving pregnancy. Its use is only evidence-supported in cases of threatened miscarriage caused by luteal phase deficiency. The mechanism involves supplementing progesterone normally secreted by the ovarian corpus luteum, thereby stabilizing the endometrium and providing continuous nutritional support for embryo implantation and early development. If serum progesterone levels are below 15 ng/mL before five weeks of gestation, especially accompanied by symptoms such as shortened menstrual cycles or delayed rise in basal body temperature, oral dydrogesterone, micronized progesterone, or intramuscular progesterone injections may be administered under medical supervision. Progesterone levels and ultrasound findings should be monitored dynamically; approximately 70% of patients can continue their pregnancies successfully.

More than half of spontaneous miscarriages result from embryonic chromosomal abnormalities, in which case additional progesterone cannot alter the outcome of genetic defects. Bleeding due to immune disorders, hypothyroidism, uterine malformations, or ectopic pregnancy will not be resolved with progesterone alone—using it may even mask the underlying condition. Therefore, individuals experiencing abdominal pain or vaginal bleeding should seek immediate medical evaluation. An initial assessment with ultrasound and laboratory tests must be performed before deciding whether progesterone supplementation is appropriate.

During treatment, avoid strenuous activity, maintain a balanced diet, moderately supplement vitamin E and high-quality protein, and attend follow-up appointments as scheduled. If ultrasound confirms embryonic demise, pregnancy should be terminated promptly to avoid increased risks of infection and coagulopathy.