Hormones in reproduction and contraception · GCSE Biology

Hormones at puberty

During puberty, reproductive hormones cause secondary sex characteristics to develop.
Oestrogen is the main female reproductive hormone, made in the ovaries. At puberty, eggs begin to mature; about every 28 days an egg is released (ovulation).
Testosterone is the main male reproductive hormone, made in the testes. It stimulates sperm production.

FSH (from the pituitary) causes an egg to mature in the ovary.
LH (from the pituitary) stimulates the release of the egg (ovulation).
Oestrogen and progesterone (from the ovaries) are involved in maintaining the lining of the uterus.
(Higher) FSH stimulates the ovaries to make oestrogen. Oestrogen inhibits FSH and stimulates LH. LH triggers ovulation. Progesterone maintains the uterus lining and inhibits FSH and LH.

Hormonal methods: the oral contraceptive pill contains hormones that inhibit FSH so no eggs mature; injections, implants and skin patches release progesterone slowly to stop eggs maturing and being released for months or years.
Barrier methods, such as condoms and diaphragms, stop sperm reaching the egg. Spermicides kill or disable sperm.
Intrauterine devices (IUDs) stop an embryo implanting, or release hormones.
Other methods: avoiding sex around the time of ovulation, and surgical sterilisation.

FSH and LH can be given in a 'fertility drug' to women whose FSH level is too low.
In IVF, the mother is given FSH and LH to mature several eggs. The eggs are collected and fertilised by sperm in a laboratory. The fertilised eggs grow into embryos, and one or two are put into the uterus.
IVF can be emotionally and physically stressful, success rates are not high, and it can lead to multiple births, which are a risk to mother and babies.

Oestrogen: The main female reproductive hormone, made in the ovaries.
Testosterone: The main male reproductive hormone, made in the testes.
Ovulation: The release of an egg from an ovary, about every 28 days.
FSH: Follicle-stimulating hormone: causes an egg to mature in the ovary.
LH: Luteinising hormone: stimulates the release of an egg.
Progesterone: A hormone that maintains the lining of the uterus.
Contraception: Methods used to prevent pregnancy.
IVF: In vitro fertilisation: eggs are fertilised by sperm outside the body.
Barrier method: A contraceptive, such as a condom, that stops sperm reaching an egg.