The Complete Reproductive Continuum
Menstrual cycle → Fertilization → Pregnancy → Parturition → Lactation
↓ ↓ ↓ ↓ ↓
FSH/LH cycle Ampulla event hCG rescues Oxytocin Prolactin+
estrogen/P4 acrosome/ corpus luteum positive Oxytocin
drives cycle cortical Rxn → progesterone feedback (let-down)
Key Hormonal Handoffs
| Transition | What Happens |
|---|---|
| Follicular → Ovulation | Estrogen (↑) → positive feedback → LH surge |
| Ovulation → Luteal | LH causes luteinization; corpus luteum forms |
| Luteal → Pregnancy | hCG (trophoblast) rescues corpus luteum |
| Early → Late pregnancy | Placenta takes over progesterone (~week 8–10) |
| Late pregnancy → Labour | Fetal cortisol → estrogen dominance → oxytocin sensitivity |
| Delivery → Lactation | Placenta out → estrogen falls → prolactin acts on mammary glands |