Roy Pitkin, M.D., is a professor of obstetrics and gynecology and is the former chair of the ob/gyn department at the University of California, Los Angeles School of Medicine. He is a frequent advisor to national health agencies on women's health issues and has received numerous international honors for this work.

Q: Can you increase your odds of having one sex baby over the other?

A: There really is no simple and effective means of selecting a baby's sex, or even altering the odds. Timing intercourse and a number of other approaches have claimed to be effective, but none has withstood careful scientific study. Of course, it is possible to determine sex very early in intrauterine life, and if the sex is not desired, abort the pregnancy. However, most physicians consider this approach unethical, except in rare cases of a sex-linked genetic disorder in which a baby of one sex will be perfectly normal but one of the opposite sex has a 50 percent chance of a serious and ultimately fatal disease.