Will baby’s sex affect the immune system of the mother? A new research explores the connection between the fetal sex and the immune response of the mother to disease.
A team of researchers from Ohio State University’s Wexner Medical Center set out to investigate whether or not there is any link between the baby’s sex and the immunity of the mother.
The team was led by Amanda Mitchell, a postdoctoral researcher at the Wexner Institute for Research in Behavioral Medicine.
Both anecdotal data and experimental studies (referenced by the authors) prompted the study, indicating that the sex of the fetus affects many physiological responses within the mother. Glycemic regulation, blood pressure, and levels of cortisol have all been shown to vary depending on the fetal sex.
For the new research, Mitchell and team examined 80 women in their early, middle, and late pregnancy phases. Among those future mothers, 46 were male pregnant, and 34 were female pregnant. Researchers exposed bacteria to their immune cells to see whether they reacted differently depending on the sex of the fetus.
The new results have been published in Brain, Behaviour, and Immunity journal.
Female fetus raises pro-inflammatory cytokine levels
In particular, Mitchell and her collaborators have investigated cytokine levels in pregnant women. Cytokines signal molecules that regulate immunity and inflammation.
These are often referred to as emergency molecules because the body releases them to fight off disease, and these help cells interact with each other while inflammation is present in the body. Cytokines are a part of the body’s normal immune response, but when released persistently, they can cause disease. This is similar to how inflammation is a key component of the immune response, but too much of it can cause pain and fatigue.
The research analyzed cytokine levels in both the blood and the laboratory sample that had been exposed to bacteria.
The results indicate women who are pregnant with girls can experience more serious symptoms of certain diseases.
“While women did not display variations in blood cytokine levels based on fetal sex, when exposed to bacteria we observed that the immune cells of women carrying female fetuses developed more pro-inflammatory cytokines. This means women carrying female fetuses had an increased inflammatory response when their immune system was tested, compared with women carrying male fetuses.
The increased inflammation observed in this study may explain why pregnant women with female fetuses continue to experience more serious symptoms of pre-existing medical conditions. Examples provided by the investigators include asthma and allergies, all of which tend to be intensified when carrying a female fetus compared to a man.
The lead investigator of the study explains what the results mean:
This research helps women and their obstetricians recognize that 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.”
Further research is needed to understand precisely how the inflammation affects pregnancy. Mitchell speculates that the inflammation levels may be caused by sex hormones, or other hormones present in the placenta.
“It’s important to think about maintaining a healthy immune system, which doesn’t automatically mean improving it – getting too little or too great an immune response is problematic,” Mitchell says. “That being said, research has shown that exercise helps good immune functioning, as does eating other foods, such as leafy greens, and relaxing through meditation practices. Before making any changes to your routine or diet, Of course, it is always important to check with your healthcare provider before making any changes to your routine or diet,” she notes.
In addition, the authors point out that more research is required on the relationship between fetal sex and other pre-existing medical conditions in the mother (such as preeclampsia), as well as negative consequences of pregnancy (such as premature birth).