Fertility can be controlled by hormonal and non-hormonal methods of contraception. Oral contraceptives contain hormones that inhibit FSH production, so no eggs mature. An injection, implant or skin patch gives a slow release of progesterone, which stops eggs maturing and being released for a number of months or years.
Barrier methods, such as condoms and diaphragms, prevent sperm reaching an egg. Condoms also reduce the risk of sexually transmitted infections (STIs). An intrauterine device (IUD) prevents the implantation of an embryo, or releases a hormone. Spermicidal agents kill or disable sperm.
A couple can also abstain from intercourse when an egg may be in the oviduct. Surgical methods of male and female sterilisation prevent pregnancy.
To evaluate a method, compare how reliable it is, whether it has side effects, whether it protects against infection, how long it lasts and whether it can be reversed. Science can give these facts, but choosing a method also depends on personal, social, ethical and religious views, so science alone cannot answer every question about contraception.