Study shows body's reactions to immune challenges predit baby genders

All kinds of theories are out there that "predict" whether a woman is pregnant with a boy or a girl. Turns out, though, they may not all just be old wives' tales. A new study puts some science behind the speculation.

While pregnant with her second child, Melissa Fox found many of the old wives' tales about the differences between carrying a girl and a boy were true. She craved different foods with her babies and she carried them differently. But what she didn't expect was the allergies she thought she had outgrown were back with a vengeance while pregnant with her daughter.

"When I was pregnant with Ren, that's when I noticed that they seemed like they were kicking up and flaring up again where I was having to take something on a daily basis," she says.

A new study at the Ohio State University Wexner Medical Center shows that it might be more than allergy season that caused Melissa's symptoms.

Researcher Amanda Mitchell led the study that followed 80 women through pregnancy and exposed their immune cells to bacteria in the lab.

"What the findings suggest is that women carrying a girl exhibit greater inflammatory responses when faced with some sort of immune challenge," she explains.

That inflammatory response includes proteins called cytokines, which the body releases to fight off sickness. The study found that the immune cells of pregnant women carrying girls released more proinflamatory cytokines than those carrying boys.

"Too many of those cytokines or too much inflammation can really be unhelpful for our bodies' functioning. It can create or contribute to symptoms like fatigue or achiness," says Mitchell.

Melissa took part in the study and says the results make a lot of sense based on her experience, but that suffering through her allergies was well worth it.

"I loved being pregnant with both of them. Obviously I love both of my children. I'm glad that they're here. But, it was really interesting to me just the differences that I experienced," she says.

The next step is to determine if this relationship exists in women with chronic illnesses. This information could inform doctors' treatment recommendations to pregnant women based on whether they're having a boy or a girl.

Activities that promote a healthy immune system like exercise and meditation are recommended to help all women stay healthy during pregnancy - regardless of what they're having.