Reproductive Endocrinology

Reproductive Endocrinology is the study of how hormones control reproduction. It covers the signal loop between the brain and the gonads, the ovaries and the testes (the hypothalamic-pituitary-gonadal axis). Those signals drive ovulation and implantation. They also drive the hormone support that sustains a pregnancy. The conventional subspecialty is Reproductive Endocrinology and Infertility (REI). It grew alongside assisted reproductive technology. IVF became the main clinical path for many clinicians with that training. Restorative reproductive medicine uses the same hormone science for a different goal. In practices such as NaProTechnology and NeoFertility, cycle-timed diagnostics find real points in the cycle. Hormone tests are timed to those points, not drawn on a random calendar date. The results then guide treatment of the cause, instead of a procedure that bypasses it. Conditions such as hypothyroidism, hyperprolactinemia, diminished ovarian reserve, and other hormonal abnormalities can add to infertility or pregnancy loss. A targeted hormone workup finds them. Clinicians can then treat them at the source.¹² Key tests include FSH, LH, progesterone, and estradiol. Those four hormones rise and fall across the cycle. For this reason, the day of the blood draw changes what the result means. TSH and prolactin do not track the cycle in the same way. Prolactin does rise with sleep, stress, and a recent meal. One draw under calm conditions is therefore usually enough to read it.³