Is Bacterial Vaginosis Caused By Sperm?

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Question: Is Bacterial Vaginosis Caused By Sperm?

Answer: No

Women who have been diagnosed with bacterial vaginosis (BV) often think that is caused by sex or by sperm. That misperception is understandable since one of the most clearly recognizable features of bacterial vaginosis is that women with BV often experience a strong, fishy smell coming out of their vaginas after having unprotected intercourse.

It's, therefore, natural to assume that it's semen -- the milky, white fluid that contains a man's sperm -- which causes the smell. It's just not true... at least not directly. 

Bacterial vaginosis is caused by an overgrowth of certain bacteria that are normally present at low levels in the vagina. No one is certain exactly what causes BV, or why some women are so susceptible to recurrent bacterial vaginosis, but one thing is for certain... BV stinks!

The smell after sex isn't caused by the presence of semen or sperm, but it is exacerbated by it. BV symptoms get worse after unprotected sex because the chemical compounds that cause the odor associated with BV are more noticeable at higher pH. Normally the vagina is mildly acidic, around pH 4. During bacterial vaginosis, the pH increases above 4.5. When semen is present, the vagina actually becomes neutral - pH 7 - and the amines, the chemical compounds that cause the "fishy smell," start to stink.

What may be a barely noticeable infection when a woman is not having sex, all of a sudden becomes very obvious when she is, particularly if she doesn't use a condom. That's why many women think that bacterial vaginosis is caused by sex. However, although BV is certainly sexually associated, and made more obvious by sex, ongoing research is still attempting to clarify any links between sexual activity and bacterial vaginosis in heterosexual couples.

Interestingly, it's pretty clear that the infection may be sexually transmitted in lesbians, but doctors and scientists are less certain how transmission would occur between a man and a woman since the penis is not as susceptible to infection by the bacteria most clearly associated with BV. 

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