(COLUMBUS, Ohio) – Most pregnant women have heard theories and old wives’ tales about the differences between carrying a girl and a boy. Some say you can tell what a woman will have, simply based on the foods she craves or the way she looks.

But a new study, conducted by researchers at The Ohio State University Wexner Medical Center, has found some science behind the speculations. Researchers followed 80 women through pregnancy, exposing their immune cells to bacteria in the lab, and noticed some significant differences.

“What the findings showed is that women carrying girls exhibited greater inflammatory responses when faced with some sort of immune challenge compared to women carrying boys,” said Amanda Mitchell, lead author of the study and a postdoctoral researcher in the Institute for Behavioral Medicine Research at The Ohio State University Wexner Medical Center. “This could mean that inflammation may play a role in why some women who are carrying girls have more severe reactions to illnesses, making symptoms of conditions like asthma worse for them during pregnancy.”

Scientists found that immune cell samples of women carrying girls produced more proteins called proinflammatory cytokines than those carrying boys, which is part of the inflammatory response. “Too many of these cytokines or too much inflammation can really be unhelpful for our bodies’ functioning,” Mitchell said. “It can create or contribute to symptoms like fatigue or achiness.”

So, there’s now some evidence behind the notion that women carrying girls may be more likely to have a harder time with illnesses during pregnancy than if they were carrying a boy.