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Some immunological complications in pregnant women tied to fetus's sex

Women who were pregnant with a girl are more likely to have heightened immunological responses when their system is challenged, according to research published in Brain, Behavior and Immunity.

"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," Amanda M. Mitchell, PhD, The Institute for Behavioral Medicine Research, The Ohio State University Wexner Medical Center, said in a press release.

Researchers studied serum levels of interleukin-6, interleukin-8, and tumor necrosis factor-α as well as lipopolysaccharide-stimulated production of interleukin-6, interleukin-8, tumor necrosis factor-α, and interleukin-1β by peripheral blood mononuclear cells incubated for 24 hours were evaluated in early, mid, and late pregnancy among 80 women, 34 of whom were carrying female fetuses. There were no significant differences in adverse outcomes observed by fetal sex, cigarette use, gestational weight gain, BMI, parity, annual income, education, marital status, race and age.

Mitchell and colleagues used linear mixed models and found that women carrying girls vs. boys had greater stimulated production of interleukin-6 at each timepoint (ps ≤ 0.03). They also had greater production of tumor necrosis factor-α in early pregnancy (P = 0.04), and interleukin-1β in mid- and late pregnancy (ps ≤ 0.05). Although there were changes in serum levels of interleukin-8 (P = 0.002) and tumor necrosis factor-α (P < 0.0001) throughout the pregnancy, there were no differences observed in any serum cytokines in relation to fetal sex (ps > 0.85).

“The current data extend the literature by showing that stimulated cytokine production by peripheral maternal [peripheral blood mononuclear cells] differs by fetal sex,” Mitchell and colleagues wrote. “It is notable that in the current study, differences in maternal stimulated cytokine production, but not serum cytokine levels were seen based on fetal sex. Thus, such associations may only be observed in the context of an immune challenge. Of note, as is common practice, the [lipopolysaccharide] stimulation protocol in this study utilized 10% human male serum. Although it is perhaps unlikely given the magnitude of response elicited by [lipopolysaccharide], it is possible that exposure to male serum affected our results. Thus, specific methodology should be carefully considered and alternatives compared in future studies.” – by Janel Miller

Disclosure: The researchers report no relevant financial disclosures.