It is already well established that the stress levels incurred during pregnancy have huge effects on the development of the fetus and the child. But now according to a new study, stress also may have an effect on the number of male births.
Pregnant women who have suffered physical or psychological stress are more likely to have a daughter than a son. This was the conclusion of the study by Vagelos College of Physicians and Surgeons and New York-Presbyterian.
Catherine Monk, director of research, published in the journal PNAS (Proceedings of the National Academy of Sciences), explains: “The mother’s uterus is the first influential home base. It is just as important as the one in which a child will be raised, if not more.”
Stress affects the baby’s gender
The team supervised 187 healthy pregnant women, between 18 and 45 years old. They were asked to fill in a questionnaire with question on about 27 indicators of psycho-social and physical stress and on their lifestyle.
About 17% of the pregnant women were psychologically stressed and showed signs of depression, anxiety and stress. 16% were physically stressed, with relatively higher daily blood pressure and a higher calorie intake compared to other pregnant women. The majority almost 67% were relaxed.
When analyzing the data collected, scientists found that mothers with high blood pressure and other signs of physical stress had four boys for nine girls (ratio 4/9). Participants who were psychologically stressed had two boys per three girls (ratio 2/3).
Stress and gender of babies: historical events confirm the link
The relationship between anxiety and gender of fetuses was observed by demographic experts. Catherine Monk recalls: “Other researchers have observed this phenomenon after historical stressful events, such as the 2001 terrorist attacks in New York City, after which the relative number of male births decreased.
The Professor of Medical Psychology at the University of Columbia added: “This emphasis on women is likely to be of a long-term nature. Studies have shown that boys are more vulnerable to adverse prenatal environments, suggesting that strongly stressed women are less likely to give birth to a boy as a result of spontaneous abortions, sometimes without knowing that they are pregnant.”
Stress also increases the risk of premature delivery
The fear of the future by the mother does not only affect the sex of the baby but it also affects the date of delivery. According to the study, it is more likely that physically stressed women with high blood pressure and caloric intake give birth prematurely than at ease mothers. In addition, the fetuses had a reduced heart rate and movement which is an indicator of slower central nervous system development.
In addition, participants with signs of psychological stress showed more complications at birth than participants with physical stress.
In addition, about 30% of pregnant women indicated that they suffer from work-related stress or depression-related stress. Such problems are associated with a higher risk of premature birth, higher infant mortality and higher rates of physical and mental disorders in children, such as hyperactivity.
The important role of moral support
The researchers also found that what distinguishes the three groups most is the importance of the social support that the pregnant women receive. For example, the more a mother is surrounded by family and friends, the more likely she is to have a boy.
The researchers are of the opinion that the support around pregnant women should be improved.
Why is this happening?
Animal studies have shown that exposure to high stress levels can increase the level of stress hormones, such as cortisol in the uterus. This may affect the fetus. She continues: “Stress can also affect the mother’s immune system, leading to changes that affect the fetus’s neurological and behavioral development.” Our research clearly showed that the mother’s mental health was important not only to her, but also to her future child.