Pregnant women are left to ponder the sex of their babies until an ultrasound can determine a male or female fetus around five months of pregnancy. A recent study suggested maternal blood pressure could predict the sex of a baby; other explanations are much more outlandish. The newest scientific study offers new information though, suggesting that the sex of a baby is linked to a mother’s immune responses.
From The Ohio State University Wexner Medical Center, researchers followed 80 women through their pregnancies, collecting blood samples to look for varying levels of cytokines. These are small proteins produced by the immune system, mostly to act as messengers to boost communication and interaction between all of the immune system’s various cells.
They found that there was not a difference in the amount of cytokines in blood samples from mothers with male versus female fetuses, yet the two cytokine populations were still not identical.
"While women didn't exhibit differences in blood cytokine levels based on fetal sex, we did find that the immune cells of women carrying female fetuses produced more pro-inflammatory cytokines when exposed to bacteria,” said principal investigator of the Brain, Behavior, and Immunity study Amanda Mitchell, PhD. “This means that women carrying female fetuses exhibited a heightened inflammatory response when their immune system was challenged, compared to women carrying male fetuses.”
This study could explain why pregnant women with female fetuses might experience particularly debilitating exhaustion or soreness as well as heightened versions of existing health problems. Fetal sex and maternal inflammation can also influence the fetus or the pregnancy in other ways, during delivery, for example. Mitchell anticipates that there are also ways that maternal inflammation affects the fetus that are still unknown, and there are also other factors that affect pregnancy separately from fetal sex.
“Fetal sex is one factor that may impact how a woman's body responds to everyday immune challenges and can lead to further research into how differences in immune function may affect how a woman responds to different viruses, infections or chronic health conditions, such as asthma, including whether these responses affect the health of the fetus," she explained.
Pregnant women can do a lot to boost the health of their immune system like increasing their physical activity, refining their diet, or lowering stress levels. “Of course,” Mitchell advised, “it's always important to check with your healthcare provider before making any changes to your routine or diet.”