For centuries, we’ve told stories about how to predict the gender of an unborn child, from "girls drain a woman’s beauty," to "craving salty foods is a sign you're carrying a boy." These are regarded as myths, but research suggests that a baby’s gender could actually have an effect on its mother’s health. According to the new research, women who carry females may experience heightened inflammation, which could make them feel worse during pregnancy.

According to the study, now published online in Brain, Behavior, and Immunity, the sex of a baby is associated with pregnant women's immune responses, and women carrying female fetuses have a heightened immune response when compared to women carrying male fetuses. This may even play a role in differences in morning sickness and cravings based on fetus gender.

“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," explained lead researcher Amanda Mitchell in a statement on Science Daily.

Read: How The Placenta Protects Girls More Than Boys

For their research, the team looked at 80 different women throughout their pregnancies, looking specifically at differences in their levels of an immune marker called cytokines. These are cell signaling molecules that aid in communication in immune responses, News Medical Life Sciences reported.They also stimulate the movement of cells toward sites of inflammation, infection, and trauma.

Although there were no differences in the levels of cytokines in women’s blood based on fetal sex, results did show that women who were carrying female fetuses had more pro-inflammatory cytokines when they were exposed to bacteria. This translates as a heightened immune response compared to mothers carrying male children, and could affect the mother's health.

While female fetuses may cause mothers to have exacerbated health concerns during pregnancy, in general male fetuses are associated with more risky pregnancies and births. One reason is because male fetuses grow faster than females, and as a result are at greater risk of lacking nutrition. For example, a 1999 study showed that historically, in times of famines, the number of healthy male births drops dramatically in comparison to female births.

Source: Mitchell AM, Palettas M, Christian LM. Fetal sex is associated with maternal stimulated cytokine production, but not serum cytokine levels, in human pregnancy. Brain, Behavior, and Immunity . 2017

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Gender Differences In The Workplace

Aging Differences Between Men And Women