How are Progesteron and fertility related?

Progesterone is a key hormone for fertility, especially in the luteal phase of the menstrual cycle. It prepares the uterine lining for implantation and supports early pregnancy. Deficiency can lead to cycle irregularities, recurrent miscarriage, or infertility. The provided context does not include specific data on progesterone and fertility; it covers unrelated topics like alcohol intolerance, FADS1 variants, or sleep chronotype. Thus, this answer is based on general medical knowledge (mechanistic, not from the given sources). Note: Progesterone testing (e.g., saliva or blood) can be useful, but interpretation should be done by a physician. Supplements or hormone therapy without medical supervision are risky.