Why is pregnancy from rape so rare?
There are several reasons for this:
• The ovum (egg) only lives for 24 hours, so for a pregnancy to occur, the rape would have to happen a day or so either side of ovulation (egg release) — a very small window of time.
• The victim may be too young or too old to conceive (pre-puberty or post-menopause).
• She may be on the pill or other contraception, or have been sterilised, or have known or unknown fertility problems.
• She may already be pregnant to her husband or boyfriend.
• Trauma from the rape may bring into play some natural defence mechanisms that reduce the likelihood of pregnancy, such as hormonal change and spasms of the fallopian tubes which inhibit ovulation or fertilization.
• Rape does not always involve a complete act of sexual intercourse — ejaculation may not occur at all, may occur prior to or after penetration, or the rapist may be infertile or have low fertility.
• The chance of conception resulting from a single act of unprotected intercourse even between consenting fertile individuals has been estimated at only 2-4%