There is evidence that mothers with male fetuses are at increased risk of preterm birth and gestational complications such as diabetes or pre-eclampsia . But until now it was not clear why this supposed disadvantage of the male sex.
A work carried out by the Autonomous University of Madrid (UAM), the La Paz University Hospital (HULP) and the University Medical Center Hamburg-Eppendorf (Germany), has shown that some important molecules in pregnancy are modulated by the sex of the fetus, influencing the levels of inflammatory cytokines and nitric oxide in pregnant women.
In other words, women pregnant with a male fetus may be less able to contain a pro-inflammatory environment, although they have more vasodilator factors than women who are pregnant with a female fetus. Physiologists from the Autonomous University of Madrid (UAM)
An important advance to prevent risks
This study, published in the journal Cytokine, analyzed the blood of 85 healthy pregnant women during week 10 of pregnancy, focusing on cytokine concentrations.
Thus, in women with male fetuses, they found higher levels of a pro-inflammatory cytokine, leading to an imbalance in pregnancy that may be the basis of a gestational disease.
Thus, in women with male fetuses, they found higher levels of the pro-inflammatory cytokine, while they were lower in the anti-inflammatory cytokine in pregnancy.
Pro-inflammatory cytokines are essential in early pregnancy for proper placentation to occur, but subsequently levels should decrease and increase anti-inflammatory cytokines. The authors explain:
“A delicate balance between pro, anti-inflammatory and chemokine cytokines is crucial for a proper pregnancy. An imbalance in favor of pro-inflammatory cytokines can be the basis of a gestational disease ”.
They add that “the placental immune response is different depending on the fetal sex, and it is possible that the placenta-male fetus unit may be more susceptible to this imbalance.”
According to the researchers:
“The dual function or evolution of these cytokines throughout pregnancy in relation to fetal sex should be thoroughly explored to understand the true role of these molecules in pregnancy health and disease.”
The study also found higher nitrate levels in pregnant women with male fetuses. Nitrates represent the end product of nitric oxide oxidation and are a measure of its concentration.
Nitric oxide is the most important vasodilator factor in the placenta, which could lead to better vascular adaptation during pregnancy and increased blood flow to male fetuses. However, this advantage can turn into a disadvantage if there is a pro-oxidant environment, as occurs in gestational diseases such as pre-eclampsia or gestational diabetes, in which many free oxygen radicals are produced.
These free radicals destroy nitric oxide and also generate peroxynitrite, a compound toxic to cells.
The higher levels of nitrates in women with male fetuses could be due to stimulation of the enzyme that synthesizes this compound (nitric oxide synthase) by testosterone, a sex hormone that is already present in the male fetus.
Finally, the authors explain:
“Together, our results show that some important molecules in pregnancy are modulated by the sex of the fetus. More research in this field would be necessary to evaluate the role of sex to predict the evolution of a gestational pathology ”.
Via | Autonomous University of Madrid
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