Reproduction, fertility and contraception

Human reproduction is controlled by hormones from the pituitary gland (in the brain) and from the ovaries in females / testes in males.

The menstrual cycle (≈ 28 days)

Day	Event	Key hormone(s)
1-5	Menstruation (uterus lining sheds)	low oestrogen + progesterone
6-13	Lining repairs and thickens	oestrogen rising (from ovary)
~14	Ovulation (egg released)	LH spike from pituitary
15-28	Lining maintained	progesterone (from corpus luteum)

If no fertilisation, progesterone falls and menstruation begins again.

Four key hormones

• FSH (follicle-stimulating hormone, pituitary) — causes a follicle to mature in the ovary.
• Oestrogen (ovary) — repairs and thickens uterus lining; inhibits FSH.
• LH (luteinising hormone, pituitary) — triggers ovulation.
• Progesterone (ovary, then placenta if pregnant) — maintains uterus lining; inhibits FSH and LH.

Contraception

Method	Type	How it works
Combined pill	Hormonal	Oestrogen + progesterone inhibit FSH so no egg matures
Condom	Barrier	Stops sperm reaching egg — also prevents STIs
Diaphragm	Barrier	Covers cervix
IUD	Mechanical / hormonal	Prevents implantation; some release progesterone
Sterilisation	Surgical	Cuts/blocks oviducts or sperm ducts

IVF (in-vitro fertilisation)

Used when a couple cannot conceive naturally.

1. FSH and LH are given to stimulate multiple eggs to mature.
2. Eggs are collected and fertilised with sperm in a dish.
3. Embryos develop for a few days.
4. One or two embryos are inserted into the uterus.

Issues: emotional/physical stress on the woman, multiple births (twins/triplets), low success rate per cycle, high cost.

CCEA tip

For "describe how the contraceptive pill works" the markscheme always wants the hormones AND the mechanism: "contains oestrogen + progesterone B1 which inhibit FSH B1 so no egg matures / no ovulation B1". Naming the hormones alone scores only 1 of 3.