Dear Curious,

No, it's not true. While some people may believe this, it is a misconception, a myth, and misinformation. Regardless of a woman's position during sex, if a man ejaculates inside her vagina, without using contraception, there is a possibility of pregnancy. After all, 300 to 500 million sperm are typically released in a single ejaculation. A man's pre-ejaculatory fluid can contain sperm, too (see Pregnant from pre-cum? in Alice's Sexual Health Archive). According to Contraceptive Technology, 85 percent of women who did not use contraception (including those who chose not to use protection because they're trying to conceive) became pregnant within a year.

Sperm can swim in different directions when they spurt into the vaginal canal. Some may shoot upwards. If a woman is ovulating (see Fertile times?), healthy sperm can potentially swim through favorable cervical mucus. If it meets up with a healthy egg, conception can occur. Others may detour down and trickle out of the vagina (check out Semen drips out after sex).

It sounds as though you are eager not to get pregnant. If that's the case, then it makes sense to talk with someone about contraceptive choices to prevent pregnancy. For further info or help in choosing contraception, couples may want to speak with a health care provider. The books, Our Bodies, Ourselves For The New Century by The Boston Women's Health Book Collective and Contraceptive Technology by Robert Hatcher, et. al., provide information on this as well as other options.

Alice

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