Katrina "Tree" Davis has four daughters. Her sister Krista has four sons.
The women believe their families are perfect just as they are, but some people would rather have symmetrical families like the one in which Davis and her sister grew up — two boys and two girls.
In hopes of achieving this, some couples take supplements, eat special diets and employ other strategies to try to "sway" an embryo's sex. Others do something more complicated and expensive: conceiving via in vitro fertilization, then picking out the embryo they want after a genetic screening.
It's a practice called family balancing.
Some couples undergo IVF for sex selection for medical reasons — for example, if a boy would inherit a disease like hemophilia. But most people do so simply because they really want a boy or a girl, fertility specialists say, and in doing so, they wade into territory fraught with ethical questions.
Choosing embryos by sex could lead to societal imbalances or contribute to sexism and discrimination, some ethicists say. Though generally safe, IVF presents slight risks to both mother and child. And fertility experts warn couples that a child of their dreams might not fulfill their dreams even if he or she arrives with the "right" body parts.
"Our kids, no matter what we think we're doing to influence them, are individuals, and they're going to become what they're going to become," said Dr. Louise King, an attorney and OB-GYN who teaches at the Center for Bioethics at Harvard Medical School in Boston.
The American Society for Reproductive Medicine has declined to take a stand on IVF for sex selection, except to advise physicians to let their clinical staff opt out of such procedures if they are morally opposed to the practice.
That leaves it to parents to decide if their desire for a child of a certain sex is strong enough to warrant the expense, trouble and risks of IVF. But both fertility doctors and ethicists say some soul-searching about what you expect from your child is important before trying to manually balance a family.
When Louise Brown, the first baby conceived by IVF was born in 1978, her parents didn't have a choice of the child being a boy or a girl. Another two decades transpired before fertility doctors could routinely biopsy the embryo to see if there were any extra or missing chromosomes, and to test for the genes that cause debilitating or lethal diseases. The biopsy, taken from cells that will ultimately develop into the placenta, also reveals whether the embryo will become a boy or a girl.
Dr. Alan Penzias, a reproductive endocrinologist at Boston IVF, who is also an associate professor at Harvard Medical School, said genetic screening does not alter the embryo; it "simply identifies a trait that is desired, or a trait that is less desired." In short, fertility specialists aren't changing the embryos, but sorting through them.
But even that ability calls for serious consideration of four ethical guidelines for biomedical research, Penzias said. Called the Belmont Principles (after the 1974 commission that drafted the report), the guidelines are autonomy, justice, beneficence and nonmaleficence. "These things all have to be weighed and thought about at the micro level, as well as the societal level," Penzias said.
For example, beneficence requires that a procedure is done with the intent of doing good; if family balancing helps the entire family by allowing children to grow up in a home with siblings of both sexes, then the physician is doing good, Penzias said. The principle of nonmaleficence demands that a procedure does not hurt the patient or others in society. To achieve this, a physician or clinic pays attention on the sex ratio of requests for family balancing. "If the clinic is being asked 90 percent of the time for one sex, that could have negative consequences on society," he said.
But Penzias and other fertility specialists say requests for boys versus girls tend to break down roughly 50/50, similar to natural conception, in which boys have only a slight edge on girls.
At Boston IVF, family balancing is offered to clients, but only after thoughtful conversation with the parent- or parents-to-be about expectations for the child, Penzias said.
Sex selection begins with basic IVF. Fertility specialists extract eggs from the mother after she has undergone hormone injections to stimulate her ovaries, then fertilize the eggs with the father's sperm in a Petri dish. Usually this results in multiple embryos, depending on the age of the parents, their health and how they respond to treatment.
The baby grows from a single cell that rapidly divides and multiplies; within a week, there are enough cells to extract several for biopsy and identify the developing child's sex.
The cells, however, don't come from the part of the embryo that will develop into the baby, but from an outer layer of cells that will eventually form the placenta. Because of this, the process isn't 100 percent reliable, although "it's fairly uncommon to get the sex of an embryo wrong," said Dr. Erica Johnstone, reproductive endocrinologist who teaches at the University of Utah Center for Reproductive Medicine.
Still, she said, "It's not an easy decision or a simple procedure. It's complex, and not without risks, and something someone should think carefully about and seek a medical consultation before making the decision."
The risks to the baby, according to the American College of Obstetricians and Gynecologists, include an increased risk of preterm birth, low birth weight and an increased death rate in the weeks before birth. Women who have IVF are slightly more likely to experience placenta previa, a condition that can cause serious bleeding before and after childbirth, and the drugs given to induce ovulation can cause a condition called ovarian hyperstimulation syndrome.
The first person to offer IVF sex selection without a medical need was Dr. Jeffrey Steinberg, a reproductive endocrinologist and director of The Fertility Institutes, which has offices in in Mexico, India and the U.S., including one in Draper, Utah.
"I was the first one to do this, and I was accused of putting everyone on the slippery slopes 25 years ago, and it's been 25 years, and no slips yet," he said.
Ninety-five percent of his clinics' patients are choosing IVF for family balancing, and the average age of the couple is 34 years old and they typically have two or three children of the same sex. Sometimes people will come in and want to select the sex of an only child. "Most programs will turn them away; we won't," he said, adding that he practices "happy medicine."
Steinberg said when he first began offering sex selection, it was "extraordinarily controversial" but he said no one was able to give him any good reasons against it. As for the "playing God" reason, which he hears a lot, he counters that people would die from appendicitis if surgeons didn't interfere.
"We're not making boys or girls. That's not allowed. All we're doing is telling people what they've made and letting them choose," he said.
Couples then must decide what to do with the embryos they choose not to implant. Their options include donating them to other couples or donating them for research.
Steinberg said he has heard every possible do-it-yourself "swaying" technique that couples use to try to conceive a boy or a girl — from women drinking gallons of hot tea, to men walking around with chilled jock straps. None of them work, he says, which is why he hears these methods from couples sitting in his office seeking IVF.
But, like Johnstone, Steinberg warns that the procedure isn't simple, and couples need to be educated about what's involved. With natural conception, slightly more boys are conceived than girls, but fertility specialists sometimes see an imbalance when embryos form in the lab. He's had cases where IVF results in 12 embryos, and 11 are male or female. "There may be a natural predisposition to producing one gender or the other," he said.
Steinberg says couples should be screened for fertility in general before signing up for IVF because even couples who conceived easily naturally might have a harder time conceiving with IVF.
"It's not so easy to do this. We need a huge number of embryos," he said, adding that even among women with no fertility issues, "about 20 percent have a hard time being supercharged with fertility drugs" to harvest the eggs.
King, with Harvard's Center for Bioethics, says that rapid advances in genetics have led some people to speculate the day is coming when all human reproduction will be done in a lab, and that men and women will only have sexual intercourse for pleasure.
"The big problem with that, and the big problem with sex selection, is the idea that we can control this in any way," she said. "From an ethics standpoint, thinking when you select a child that is female by genetics, that you're going to get some type of child is a fool-hardy exercise."
King said couples could have the girl they want and then discover that she has no characteristics that they were expecting, or they could have a boy and discover that he has characteristics that they consider girlish.
"Creating those types of expectations for children is certainly in keeping with our history as human beings; we have children for a million different reasons," she said.
"But from the standpoint of just common sense, I think it's important to encourage families to understand that all this control they're trying to exert is rather absurd. We should be encouraging families to be very happy with the children that come to them."
Davis, the mother of four girls who lives in Hawaii, grew up in a family that was naturally "balanced" — two boys and two girls. So it was a surprise when Davis and her husband had all girls, and her sister, who lives in Florida, had all boys. While they joked that they should switch their fourth babies, Davis said her sister called right after her fourth son was delivered and said couldn't believe she had joked about trading him for a girl, because "she was already so in love with him."
Additionally, Davis said she and her sister were a surprise to her father, who'd wanted a son so he could share his love of sports. "My sister and I wound up being much better athletes than the boys," she said.
While Davis and her husband experienced a little bit of sadness knowing they would never have a son after their last daughter was born, they're happy with their family the way it is.
"My husband is in the military and spends his time predominantly with men, and he loves to come home to our home full of girls," she said. "And I feel like it wasn't our decision to make."
For those who feel differently, Steinberg's fertility clinic in California has a new option for couples who come to him wanting IVF for sex selection. About a year ago, the clinic beginning offering eye color as a choice, too. So far, he says, the success rate is close to 80 percent.