Estradiol-to-Progesterone Ratio
The estradiol-to-progesterone ratio compares two hormone levels measured in the same cycle. Estradiol is the main estrogen. Progesterone rules the second half of the cycle. The ratio describes the balance between them, not the amount of either one.
Balance is worth measuring. The two hormones act against each other in the uterus. A ratio can rise because progesterone falls, not because estradiol climbs. One hormone read on its own hides that. In 12 women with carefully defined unexplained infertility, mid-luteal progesterone ran lower than in 12 fertile women. The ratio ran higher.1
The ratio also shifts across every normal cycle. A 1991 review tied those shifts to seizures that cluster with the period.2
Cited in this entry
- Blacker CM, Ginsburg KA, Leach RE, Randolph J, Moghissi KS. Unexplained infertility: evaluation of the luteal phase; results of the National Center for Infertility Research at Michigan. Fertility and Sterility. 1997. https://pubmed.ncbi.nlm.nih.gov/9091327/
- Herzog AG. Reproductive endocrine considerations and hormonal therapy for women with epilepsy. Epilepsia. 1991. https://pubmed.ncbi.nlm.nih.gov/1959509/
This content is for educational purposes only and does not constitute medical advice. Consult an RRM clinician or healthcare provider for guidance specific to your situation.
