Sex fascinates many -- if not most -- people. It is considered an integral part of many marriages and other romantic relationship, drives wedges between young people and parents and, let's not forget, keeps the species going.

Despite its importance, some people cling to myths about sex. Holding beliefs about what is right or wrong, or what is fun or not, can be personal and often don't have obvious implications. But getting the facts wrong about conception can cause a surprise pregnancy and a host of other consequences.

Dr. Laura Berman says on her Web site that one of the big falsehoods that people believe is that women can't get pregnant the first time they have sex.

"You can get pregnant any time you have sex, whether it's the first, second, third, or thousandth time!" she writes. also takes on a slew of misconceptions about conception.

The site points out that women get pregnant even if they're breastfeeding, don't have an orgasm or use the withdrawal method of birth control. None of those things can do much to prevent pregnancy.

Having her menstrual cycle timed down to the minute can make it more difficult for sperm to reach and egg, but since they can live in the body for quite some time, and the cycle of a woman's body is never that precise, accidents can happen.

Men, Women Not That Different

As for getting ready for sex, many people believe the notion that something visual has a greater effect on most men than most women. But a says even that isn't true.

Researchers studied the brain activity of men and women shown full-color slides, some of which showed sexual activity. The authors of the study said that there were not differences in the reactions based on gender.

And, lastly, remember what the experts say: No matter what TV ads and spam e-mail say, a pill can't give you a size boost.