Believe it or not, after millennia of fervent (and often hilarious) experimentation with different ways to conceive, we still lack conclusive evidence about the very best positions to get pregnant. "There's not a whole lot of science about which position is best for conception," says Sheryl A. Kingsberg, Ph.D., chief of the Division of Behavioral Medicine at University Hospitals Case Medical Center and a professor of reproductive biology and psychiatry at Case Western Reserve University School of Medicine in Cleveland. It's more of a logistical issue than anything else. "It is very difficult to research specific sexual positions that might enhance fertility when there are so many other variables that go into it," Dr. Kingsberg says.
The few studies that have looked at coital connections hint that missionary position might offer a slim anatomical advantage. The theory: In guy-on-top, a woman's cervix can dip more easily into the vaginal semen pool, giving sperm access to the protective cervical mucus. "There's no scientific data on that, though," says Kelly Pagidas, M.D., a fertility specialist with Women & Infants Center for Reproduction and Infertility in Providence and an associate professor at Brown Alpert Medical School. Plus, not all women are built the same way. "Having women on their backs makes sense for women who have an anteverted uterus, one that is tilted forward, which is about two-thirds of the population," Dr. Kingsberg notes. "But a third of women have a retroverted uterus, one that's tilted backward, so missionary wouldn't offer any advantage for them."
Chances are, you don't know your own uterine alignment anyway, so who's to say whether it would benefit you? Also, missionary might even hurt your guy. "The missionary position is more demanding for men because they have to use their muscles to keep from putting their full weight on you, putting extra pressure on them," says Mindy R. Schiffman, Ph.D., a clinical psychologist and sex therapist at New York University's Fertility Center and in private practice in New York City.
It's more likely that the very best position is, in fact, your favorite one. It doesn't matter if you're twisted like a Bavarian pretzel or lying still as a statue, as long as your partner gets the job done. And if it provides a toe-curling climax, so much the better! "There was some research that a woman's orgasm did help move semen into the uterus terms of the contractions," Dr. Kingsberg says. But she cautions against stressing if you don't regularly climax. "Honestly, there's so little science behind it that we don't want to put pressure on women to have to reach orgasm."
What's most important is to keep up a consistent routine, and not necessarily an obsessive one. "In studies about frequency of sex, there wasn't a statistical difference between rates of pregnancy for people who have intercourse every other day leading up to ovulation and those who do it every day," says Jani Jensen, M.D., a reproductive endocrinologist and assistant professor at the Mayo Clinic in Rochester, Minnesota. "Besides, trying to have it daily can be a huge chore."
The optimal postcoital routine is another aspect of baby-making sex that's up for debate. Most experts question the advice that you should lie still on your back for 30 minutes after having sex, yet others swear by it. Our view: If you've got time to lounge, why not enjoy the afterglow? Propping yourself up on a pillow or putting your legs up the wall, however, have not been shown to make a difference. "Once the ejaculate gets inside you, the sperm is already in the cervical mucus, which works to hold sperm there for fertilization," Dr. Schiffman says.
There is one other thing factor that can influence your chances of conception: lubricant. Regular water-based lube has been shown to negatively affect sperm survival. Look for versions that are hydroxyethyl cellulose-based, and read labels carefully to make sure they don't contain spermicide — which, um, obviously won't help!