Physical and psychological stress that lead to less male births identified, claims study
Shortly after the 9/11 terrorist attack, researchers spotted a pattern: they found a relative decrease in the number of male births. By piecing together evidence triggering such unusual patterns during stressful events, scientists had found that stress -- physical and psychological -- was taking a toll on pregnant women, causing less male births.
Now, a new study by researchers at Columbia University Vagelos College of Physicians and Surgeons and NewYork-Presbyterianin has identified the types of physical and psychological stress that has a bearing on birth outcomes.
The researchers found that 30 percent of pregnant women report going through psychosocial stress from job strain or depression and anxiety. Earlier studies have pointed out that stress in expectant mothers can affect the unborn child, who may end up developing attention deficit hyperactivity disorder (ADHD) or cardiovascular disease later in their lives. It could also disturb brain development in children as it could affect a brain region associated with psychiatric disorders. And stress affects the fetus and the mother: low-birth weight and premature birth in babies and postpartum depression in mothers.
In this study, researchers studied 187 pregnant women, aged between 18 to 45. The participants were given questionnaires to assess their psychosocial, physical, and lifestyle stress. Based on their responses, they found that while about 17 percent of them were psychologically stressed in the form of depression, anxiety and perceived stress, 16 percent were physically stressed, showing relatively higher daily blood pressure and greater caloric intake than other healthy pregnant women. The rest of the group, close to 67 percent of the participants, were found to be healthy.
The scientists also estimated the extent to which stress in mothers-to-be influenced birth outcomes. They found that stressed mothers gave birth to more girls: the physically stressed group had four males for every nine females born and those in the psychologically stressed group gave birth to two males for every three females.
Explaining how stress leads to relatively few male births, professor Catherine Monk, the author of the study, said in a press statement, "This stress in women is likely of long-standing nature; studies have shown that males are more vulnerable to adverse prenatal environments, suggesting that highly stressed women may be less likely to give birth to a male due to the loss of prior male pregnancies, often without even knowing they were pregnant."
But stressed mothers can get help through social support. Monk and team showed that when these women received support, the effect of stress on the child's sex faded.
"Screening for depression and anxiety are gradually becoming a routine part of prenatal practice. But while our study was small, the results suggest enhancing social support is potentially an effective target for clinical intervention," Monk said in a press statement.
The study was published in the Proceedings of the National Academy of Sciences journal.