Coitus interruptus means
Intentional withdrawal to prevent sperm deposition in vagina
Coitus interruptus is the most simple method of natural contraception. This is where the male makes sure that the sperm is not deposited into the vagina of the woman by intentionally withdrawing the penis just before ejaculation. This mode of contraception is easy, free and has no side effects, and does not affect the woman’s fertility at all, meaning the couple can conceive whenever they choose. But mistakes happen, and semen may leak out before ejaculation. Around 15 to 30% who depend solely on this method, conceive, and hence is very unreliable.