Ask the Sexpert

Dear Sexpert,\nWhat positions are least likely to get a woman pregnant? Also, during which weeks of the month in relation to her period cycle is she least likely to get pregnant? Is there an effective way to keep track of this?\nRhythm-master\nDear Rhythm-master,\nOK, let's start with the basics. Is your penis in her vagina? If the answer is yes, then she is very likely to get pregnant. It doesn't matter if you're on top, on bottom or standing on your head. Any time you ejaculate inside the vagina without any form of contraception, the woman is at risk for pregnancy. End of story.\nBut there are different times of the month when a girl is more fertile. Planning your sex life around the ups and downs of the menstrual cycle is known as the "rhythm method" or "natural family planning." While this is a somewhat popular method, especially in religious families where artificial means of birth control are frowned upon, let it be known that I do not endorse this as a highly effective birth-control method. Hormones, as we all know, are very unpredictable, and it is very easy to screw up when you're relying on the rhythm method. I would also like to point out that the rhythm method offers absolutely no protection against the transmission of sexually transmitted diseases.\nA woman is most fertile during ovulation, which is when one of her ovaries releases an egg to be fertilized. On a clockwork-regular 28-day cycle, ovulation occurs roughly halfway between periods. It is important to note that the egg can live for one to three days, and sperm can survive in the vagina for two to seven days. So you should prepare for a nine-day danger zone: five days before ovulation, the day of ovulation and three days after ovulation. That leaves 19 days that are considered "safe," but don't forget that four to seven of those "safe" days will be occupied by the woman's period. So unless you aren't squeamish about blood, you've got about 12 to 15 days.\nIn order for the rhythm method to work, the woman has to "chart" her fertility patterns by paying close attention to the changes that occur throughout her cycle. There are several ways to do this: the temperature method, the cervical mucus method and the calendar method. The most effective thing to do is combine all three methods, resulting in what is known as the "symptothermal method." She must take her body temperature every day before getting out of bed (it will rise slightly on the day of ovulation), observe changes in her cervical mucus (it will become thicker and clearer during ovulation) and track her cycle on a calendar to make sure her periods are regular. Sounds like a lot of work when you could just as easily buy condoms or go on the pill, huh?\nI can't stress enough how risky this method is. Under normal use, 20 out of every 100 women who rely on the rhythm method will get pregnant. If it's used perfectly, that number drops to three, but perfect use is extremely rare. First, your girlfriend has to be absolutely positive her cycle is completely regular. Second, exactly how closely do you keep track of your girlfriend's menstrual cycle anyway?\nSend all your questions and comments to the Sexpert at jfinkel@indiana.edu.