Researchers Found Stressful Pregnancy May Affect Baby's Gender
Thu, January 27, 2022

Researchers Found Stressful Pregnancy May Affect Baby's Gender

A stressful pregnancy can affect the gender of a child, according to the researchers / Photo Credit: 123RF


Researchers have identified the types of stress during pregnancy that may affect the development of the child's gender as well as increase the risk of preterm birth.

Lead author Catherine Monk said the womb is as important and as influential of a home as the one a child is raised in after they are born. While a baby's sex is dictated upon conception, Monk said pregnancies with boys are at a higher risk of complications.

The study was published in the online journal Proceedings of the National Academy of Sciences, where researchers from Columbia University Vagelos College of Physicians and Surgeons and NewYork-Presbyterian examined the indicators of psychosocial, physical, and lifestyle stress of pregnant women.


Stress leads to fewer boys

The study analyzed 27 stress indicators collected from questionnaires, diaries, and daily physical assessments of 187 otherwise healthy pregnant women aged 18 to 45.

Among them, 17 percent experienced psychological stress—including high levels of depression, anxiety, and perceived stress—while 16 percent were physically stressed and experienced higher blood pressure and significant caloric intake compared to other participants. The remaining 67 percent were healthy, according to science news aggregator Science Daily.

Pregnant women who experienced psychological and physical stress are less likely to conceive a boy, the study said.



The average ratio of male-to-female birth is 105:100. But the collaborative study found that that physical and psychological stress leads to more female births, with the male-to-female ratio resulting in 4:9 and 2:3, respectively. This finding supports earlier works that suggest lower male births in maternal stress.

Monk said this pattern was previously seen after "social upheavals" like the 9/11 terrorist attacks in New York, in which the number of male births relatively decreased.

"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."


Complications from stress

The researchers found that 22 percent of physically stressed pregnant women birthed their child about a week earlier compared to healthier pregnant women (five percent). Their child also showed indications of slower development of the central nervous system.

Pregnant women who were psychological stressed experienced more birth complications compared to the physically stressed group, according to the study. It added that this finding is "consistent with previous findings among offspring of women with psychiatric illness."



A 2012 study found that pregnant women under pressure had higher levels of cortisol, a stress hormone that alerts the body of "flight or fight" situations. It's meant to dissipate once the threat has gone, but high levels of cortisol increase blood pressure and make a person more vulnerable to illnesses.

The high cortisol levels found in pregnant women were also present in their child's amniotic fluid at 17 weeks of pregnancy, CNN reports.

Laura Berman, assistant clinical professor at the Feinberg School of Medicine, said stress during pregnancy poses a threat to both the mother and the baby.

"Being stressed while expecting can increase a woman's chance of postpartum depression. It can also lead to preterm delivery and low birth weight," noted Berman, who was not part of the recent study.


Importance of social support

An estimated 30 percent of pregnant women report psychosocial stress from job strain or related to depression and anxiety, according to Science Daily. This stress has been linked to increased risk of premature birth, which is associated with higher infant mortality as well as physical and mental disorders.

But providing pregnant women with social support may curb these effects.

The study found a significant difference in terms of social support between the three groups analyzed in the study, with greater support being associated with increased chances of giving birth to a boy. The risk of premature birth also disappeared across all groups when expectant mothers received social support.

Even though the study was small, Monk argued that the results show that enhancing social support can be a potentially effective target for clinical intervention.


Social support is important for pregnant mothers to reduce the stress they feel / Photo Credit: 123RF


"The support could be from family and friends," the author told CNN. "It could be a sense of belonging in a religious community. It's the sense of social cohesion and social connectedness which research suggests is a buffer against the experiences of stress. It means you take a break from it."

While the study and others before it associate stress with pregnancy complications, expectant mothers should be cautious in associating the two. Stress is part of life that can actually be good for people if it motivates them and lets them focus. It only becomes a risk to their health when stress becomes overwhelming or constant.

Pregnancy is among the most crucial moments in women's lives as it redefines their perception of themselves, their families, and their communities. Providing them with moral support through this period not only helps lessen their stress but also ensures that both the expectant mother and baby are at their prime health.