Birth control

Birth control - taking control over if and when a couple have a child

It may involve contraception - preventing fertilisation when sexual intercourse takes place

There are also several methods of birth control that do not prevent conception, but rather prevent the tiny embryo from implating into the lining of he uterus. These can be termed anti-implantation methods and include use of intra-uterine devices (IUDs) and the 'morning after' pill. 

We will look at the methods that use hormones to prevent pregnancy.

The birth control pill

• the pill contains steroid hormones that surpress ovulation
• usually synthetic hormones because natural ones are not broken down so rapidly in the body and therefore act for longer
• some forms of the pill contain progesterone only, but most contain progesterone and oestrogen and are known as 'combined oral contraceptives'
• there are many different types, with slightly different ratios of these hormones because different womens bodies respond differently to the pill
• with most types of oral contraceptives;
  • the woman takes one pill daily for 21 days and then stops for 7 days during which menstruation occurs
  • for some types, she continues to take a different coloured, inactive, pill for these seven days

Both oestrogen and progesterone suppress the secretion of FSH and LH from the anterior pituitary gland. (negative feedback)

• in the menstrual cycle, highest concentrations of FSH and LH are produced when the concentration of oestrogen starts to fall and when progesterone concentration has only just…