Fertility data indicates that typically, 85% of women of child-bearing age having regular sexual intercourse using no contraception could expect to be pregnant within a year.¹⁰

In terms of contraceptive effectiveness, the number of women who could expect to become pregnant within a year is estimated at:^10,11,12

• 05% - implant (containing a progestogen – etonogestrel)
• <1% - hormonal coil containing a progestogen
• <1% - copper coil (intra-uterine device/IUD)
• 3% (0.2% to 6%)- depo injection (progestogen – usually medroxyprogesterone acetate but norethisterone enantate can be used short term for 8 weeks protection eg while partner’s vasectomy heals or following rubella immunisation)
• 9% - COCP*
• 9% - POP/minipill*
• 9% - patch (oestrogen + progestogen)
• 9% - vaginal ring (oestrogen + progestogen)
• 12% -diaphragm
• 15%-18% -condoms
• 22% - withdrawal
• 24% - fertility awareness (natural family planning)
• 28% - spermicides

* Theoretical effectiveness of pills could be much higher (less than 1% pregnancy rates) if taken ‘perfectly’ at the right time each day without missing doses, with no vomiting or diarrhoea, and with no impact from concurrent medications or diet.¹⁰