Heads a girl, tails a boy. For most couples, the odds of predicting the gender of their child are roughly the same as flipping a coin.
Of course, that hasn’t stopped people from trying to find ways to skew the numbers.
For millennia, the best attempts of soothsayers, wisewomen and quacks at sex selection have failed in the face of Mother Nature’s blithe indifference. But nowadays, it’s fertility specialists who have figured out how to load the dice. While the most reliable, high-tech alchemy takes place in the laboratory, there are also some low-tech approaches for the bedroom. Most don’t come with any kind of guarantee, but there are options to consider.
Old Wives’ Tales (Hit or Miss)
Before discussing the high-tech certainties and the bedroom possibilities, let’s first look at the historical absurdities. For instance, in eighteenth-century France, men who wanted a boy would tie a string around their left testicle because they believed that male sperm came from the right (sounds painful).
There was a time the moon was thought to play a role. People have long believed the moon to be responsible for everything from werewolves to sleepwalkers and maybe even bad hair days. So why not babies? One old belief has it that intercourse during a full moon helps conceive a girl, while a quarter moon leads to boys.
Finally, consider the Chinese conception chart, which apparently was discovered in a royal tomb over 700 years ago. The chart predicts gender by cross-referencing the age of the mother at the time of conception with the month the baby was conceived. In my case it turned out to be spot on. At age 34—in July—I conceived my son. But then again, a girl prediction would have been fine, too. His sister is just two minutes older. Alas, no clinical studies have been able to confirm the chart’s predictive powers. (But you can try it out yourself with our Chinese gender predictor.
Low-Tech Techniques (Far From Foolproof)
Peg Walker, 42, from Clarence Center, New York, is convinced she conceived the two children of her choice because she followed the advice of a book on predicting ovulation. According to the late Landrum B. Shettles, M.D., Ph.D., author of How to Choose the Sex of Your Baby (Doubleday, 1997), female sperm outlive male sperm but swim more slowly. He reasons, therefore, that the shorter the interval between intercourse and ovulation, the greater your chances of conceiving a boy. When trying for a girl, Dr. Shettles recommends you stop having sex two days before ovulation.
Walker’s children, now 9 and 11, are the result of meticulous temperature charting every morning. Walker, who says her cycle is an extremely regular 28 days, noticed a definite temperature spike every month on menstrual cycle days 15, 16, or 17, indicating ovulation. So Walker, who wanted girls, decided to try on day 14. The first month nothing happened. The following month it worked. A girl! For the next child she followed the same procedure. And again she got what she wanted: another girl.
How reliable this method is depends on whom you ask. A study published in the New England Journal of Medicine in 1995 concluded that the timing of intercourse in relation to ovulation has no influence whatsoever on the gender of the baby. Evidence to support the method is mostly anecdotal. But individual success stories can be compelling, especially when you know the person firsthand. Walker is a believer. One of her sisters who used the same method also conceived two girls by having unprotected sex on day 14 of her cycle, while her other sister, an ob/gyn, tried and failed at a second girl. But Walker has an explanation. Her physician sister, she says, didn’t have a regular cycle at the time.
Another technique, called the Whelan Method, contradicts Dr. Shettles’ advice. In this method, described in the book Boy or Girl? (Pocket, 1991) by Elizabeth Whelan, Sc.D., couples wanting boys should have sex four to six days before basal body temperature goes up, because proponents of this method believe that the conditions favoring boy-producing sperm occur earlier in a woman’s cycle. Sex two to three days before ovulation favors a girl. Again, there’s little evidence that the odds can be influenced this way, but, as always, you’ve got half a chance.
And for all the other advice on how to influence a baby’s sex with diet (eat veggies, sweets, and high-calcium foods for a girl, but red meats and salty snacks for a boy) and sexual positions (missionary for girl, rear-entry for boy), nothing has been proven to change those pretty much immutable 50-50 odds.
High-Tech Options (Science ups the Odds)
Science offers couples three ways to try and influence Mother Nature: sperm-spinning, preimplantation genetic diagnosis (PGD), and MicroSort.
So-called sperm-spinning is the least reliable of the techniques. In one method, called the Ericsson Albumin Method, sperm is repeatedly made to swim through albumin—a sticky protein substance in the blood. Since sperm carrying the Y-chromosome (male) generally swim faster than those carrying the X (female), the sperm can be sorted somewhat crudely on the basis of their speed. Clinics that use this technique claim a success rate of 78 to 85 percent for boys, and 73 to 75 percent for girls. The cost is approximately $600 to $1,200 per try.
Many experts, however, have challenged the effectiveness of sperm spinning. For Jennifer Merrill Thompson, who reviewed the data on the method as part of the research for her book Chasing the Gender Dream (Aventine Press, 2004), the evidence against it is compelling: “In my experience there are so many failures [wrong sex] with that method that I really can’t recommend it.”
Next in line in terms of accuracy is cytometric separation technology, commonly referred to as MicroSort. First used in livestock, the Genetics & IVF Institute in Fairfax, Virginia, holds the exclusive license to apply this technology to humans. The MicroSort approach also starts with the semen. The sex of a child is determined by the gender of the individual sperm cell that fertilizes the woman’s egg. Sperm cells carrying an X-chromosome result in a girl and those carrying a Y-chromosome in a boy. The MicroSort separation technology exploits the measurable difference in size between the X-chromosome and substantially smaller Y-chromosome. In order to use MicroSort, would-be patients have to become part of the ongoing clinical trial. Qualifying reasons are sex-linked genetic diseases or the desire for family balancing.
Author Jennifer Merrill Thompson, 42, of Vienna, Virginia, says she always wanted a girl. When her second child turned out to be another boy, Thompson was distraught. “I love him very much,” she says, but she still pined for a daughter. “I just didn’t just want to be an all-boys mom. It was really hard for me to see all these baby girls and think I would miss out.” That’s when Thompson decided to investigate high-tech options. Living just 15 minutes away from the MicroSort labs made things somewhat more convenient for her. After five unsuccessful rounds of IUI (intrauterine insemination) combined with MicroSort technology, and one successful round of IVF (in vitro fertilization), again employing MicroSort, luck was a lady at last.
But cytometric separation technology is not yet advanced enough to eliminate chance from the gender crap shoot. Currently it’s impossible to create all-female or all-male semen samples. Sorting errors can occur with semen separation, especially when sorting for a boy, as the male sperm is harder to isolate than the female. On average, female or X-bearing sperm can be isolated to a concentration of 88 percent, while that of Y-bearing male semen after sorting is 73 percent. In practical terms, it means that those who employed MicroSort hoping for a girl got it right 91 percent of the time, while those trying to become parents of a boy succeeded 76 percent of the time.
Finally: A Sure Bet
The most effective new method for sex selection is preimplantation genetic diagnosis (PGD), a technique used in conjunction with IVF to identify genetic disorders, but which can also identify an embryo’s sex. With PGD, embryos are tested before they are transferred into a woman’s womb. The most common use of the procedure is in women with recurring pregnancy loss, in families with genetically transmitted diseases to rule out chromosomal abnormalities, and in older women undergoing IVF to check the health of the embryos prior to implantation. Most agree that these specific medical conditions justify the use of PGD.
Increasingly, though, PGD has been attracting interest as a gender predictor, and that has caused some ethical concerns. Citing issues of possible sex discrimination and a burden on limited medical resources, the American Society for Reproductive Medicine has voiced concern. Many infertility clinics reserve PGD only for patients who can demonstrate medical need, a policy that Joseph C. Isaacs, president of Resolve: The National Infertility Association seconds. “Where does it end with the mapping of genes? Selecting for athletic ability or perfect musical pitch? One could start trying to have designer babies,” Isaacs says. “And it’s really about building families, not the perfect child.”
The draw of being able to pick a child’s gender is causing many couples to visit the U.S. from far away, especially if the procedure is illegal in their own country. Some fertility specialists who are willing to use PGD for gender selection report that more than 50 percent of the couples they treat are now from outside the United States. Would-be parents from China, Hong Kong, Singapore, Thailand, Japan, Germany, Britain, and Canada are flocking to these U.S. clinics. While biologists are concerned about the impact of gender balancing on populations such as China, which heavily favor boys, defenders of the technology argue that PGD would be much more humane in some countries than the abandonment of newborn girls or the selective abortion of “wrong-gender” fetuses. For the time being, PGD’s hefty price tag—about $15,000 to $20,000—makes its widespread use for gender selection rather unlikely.
Paul W. Zarutskie, M.D., reproductive endocrinologist, and founder of the Zarutskie Fertility & Endocrine Institute in Laguna Niguel, California, performs PGD regularly. “I see women between 40 and 43 who want a shot at this [having a child] but who don’t want to risk a disabled baby.” Roughly 60 percent of his patients who opt for PGD fall into the two categories of advanced maternal age and habitual pregnancy loss—the remaining 40 percent are patients who have undergone unsuccessful rounds of IVF elsewhere or who simply want to pick the gender of their future child. Dr. Zarutskie lets the couple decide.
“I don’t go out and advertise ‘Come to me and get your girl,’” Dr. Zarutskie says. “I don’t advertise because it’s a political issue.” The doctor, who requires all his IVF patients to undergo counseling prior to treatment, says he would turn down requests that he finds unethical. “If you’re just doing it with no clear reason—I wouldn’t do it.”
One of Dr. Zarutskie’s patients is Brandi Wojtiuk from Placentia, California. Currently pregnant with her second child, Wojtiuk had her first child, son A.J., in 2004 after her second IVF attempt. For four and a half years, the mortgage broker from Orange County had struggled with infertility before being told at age 29 that she might be entering early menopause. Despite the hormone stimulation that is part of IVF, Wojtiuk produces very few eggs. That’s why for the current pregnancy the couple didn’t want to take chances. They decided to use PGD in order to select the most viable embryos.
Of the seven eggs harvested, two were bad right from the start, while five fertilized and started to grow in the lab. Four embryos made it to the PGD testing stage—two boys and two girls. In the end, two healthy male embryos remained. “Had there been any girl eggs, I would have picked them. But I’m happy to get something,” says Wojtiuk. “Beggars can’t be choosers. My worst fear was that I had nothing to go in there. I really wanted a healthy baby.” But the 33-year-old isn’t finished with her family building, and is still determined to have a daughter. “Next time we’ll do it again. We’ll do spinning or sperm sorting and PGD. Maybe we’ll get our girl then.”
A version of this article originally appeared in the Fall 2006 issue of Conceive Magazine.
Check out our gender predictor for more fun ways to tell!