Humans have been trying to find ways to influence the sex of their baby for centuries, but when it comes to birth, “there really are no sexual positions that affect the sex of the baby,” says Jeffrey Steinberg, M.D., director of the Gender Selection Program at the Fertility Institute in Los Angeles. That is, sexual positions don’t affect whether you have a boy or girl.
For better or worse, despite the fascinating myths surrounding gender selection, most of us are still at the mercy of Mother Nature when it comes to the gender of our children. Think about it: “To have a boy, eat meat and salty foods, to have a girl, eat lots of desserts.” Or, “If you want a boy, have sex standing up or during a full moon, but if you want a girl, stick to the missionary position and have sex during a full moon.”
You can also check out 700-year-old Chinese fertility charts that tell you the day you will conceive a boy or girl based on the ages of the expectant parents and the month of conception, but there’s no scientific evidence that any of these are effective.
In a study published in the Journal of the American College of Obstetrics and Gynecology , researchers in Massachusetts looked at birth records of babies born between 1995 and 2008 to see if the claims that these charts are 93% to 99% accurate were true. But what they found was that the odds of correctly guessing a baby’s gender were about the same as flipping a coin.
But gender selection is big business. You may have noticed gender selection kits being sold online that promise results with vaginal douches, vitamins, or do-it-yourself artificial insemination kits. None of these kits have been scientifically approved.
The best-known book on gender prediction is by IVF pioneer Dr Landrum Shettles, who in the 1960s first reported on the distinct characteristics of X-chromosome (which produces girls) and Y-chromosome (which produces boys) sperm and outlined a non-invasive, low-tech family planning technique.
For example, the late Dr. Shettles advised couples seeking men to have sex as close to ovulation as possible because that’s when vaginal and cervical fluids tend to be most alkaline, making them most fertile for unhealthy Y sperm. But further research has found that Dr. Shettles’ theory is probably about as effective as a coin toss.
In 2016, researchers found no association between the style or timing of intercourse and the gender of the baby conceived. And in 2020, researchers rejected claims that sperm carrying a Y chromosome are more vulnerable. They concluded that aside from DNA content, there are few obvious differences between sperm carrying an X and a Y chromosome.
“There’s really very little you can do at home to select the gender of your baby,” Dr. Steinberg sums up. If you’re really determined to have a girl, medical procedures to select sperm or embryos offer more promise, but the ethics of these are being debated on all sides.
Some call this trend “embryo shopping” and say it’s unethical to manipulate genes to select traits like gender or eye color. But others say it could be worth it if the science could also be used to eradicate disease.
While questions about a baby’s gender are often limited to male (XY) and female (XX), it’s important to note that nature offers many more chromosomal options. According to the Intersex Society of North America, roughly 1 in 1,500 to 1 in 2,000 births “are born with genitalia abnormal enough that they require the assistance of a specialist to determine the gender.” However, the organization adds that “many more people are born with more subtle sexual anatomical variations.”
The Intersex Society of North America defines intersex as “an umbrella term that describes a range of conditions in which people are born with genitalia or genitalia that do not fit the traditional definitions of female or male.” Determining who is intersex and who is not is very difficult and cannot be predicted by folklore, like predicting who is male and who is female.
While science may not support superstitious ideas about gender selection or prediction, it never hurts to experiment a little for fun.
Editor’s Note
While the terms “gender” and “boy” and “girl” are sometimes used in this article, it is important to note that gender is an individual’s identity that exists on a spectrum, can change throughout life, and is most importantly, something a person defines for themselves. Gender, on the other hand, is assigned at birth based on the shape of a baby’s genitals. Gender assigned at birth typically matches a person’s sex (referred to as cisgender), but may not match for transgender, intersex, and gender non-binary people.
