Methods of contraception include use of hormones and barrier methods - Edexcel - GCSE Biology Combined Science - Question 4 - 2021 - Paper 1

A barrier method of contraception may be used alongside a hormonal method to provide additional protection against sexually transmitted infections (STIs) and to increase the effectiveness of preventing pregnancy.

The endocrine gland that releases oestrogen is the ovary.

High levels of oestrogen and progesterone in the combined contraceptive pill work together in the following ways:

1. Inhibition of FSH production: Oestrogen inhibits the production of Follicle Stimulating Hormone (FSH), preventing eggs from maturing in the follicles.

2. Inhibition of LH production: High levels of progesterone inhibit the release of Luteinizing Hormone (LH). Without LH, ovulation does not occur.

3. Thickening of cervical mucus: The presence of these hormones causes the cervical mucus to thicken, which makes it difficult for sperm to enter the uterus.

4. Prevention of uterine lining development: These hormones also prevent the buildup of the uterine lining, making it unfavorable for implantation should fertilization occur.

Clomifene therapy: Clomifene citrate is used to stimulate the ovaries to produce more eggs. It works by blocking estrogen receptors, leading the brain to increase the release of FSH and LH, which promotes the maturation of eggs.

IVF (In Vitro Fertilization): IVF is a procedure where eggs are harvested from the ovaries and fertilized with sperm in a laboratory setting. This method can help women who have difficulties with natural conception, as it bypasses various barriers to fertilization and can result in embryo transfer to the uterus.