Stressed Moms are Less Likely to Deliver Baby Boys

Stressed Moms are Less Likely to Deliver Baby Boys

by Dr. Lakshmi Venkataraman on Oct 15 2019 3:49 PM
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  • Mothers stressed physically and psychologically during pregnancy are more likely to give birth to girl babies as well as having an increased risk of preterm labor
  • The womb is the first home of the fetus and previous studies have shown maternal stress during pregnancy affects normal fetal development with unfavorable birth outcomes
  • The amount of social support a mother receives from family and friends could be a key factor in increasing the likelihood of having a male baby as well as reducing the risk of preterm birth
Increased maternal physical and mental stress during pregnancy can affect the gender of baby and increase the risk of preterm birth, according to a recent study led by Catherine Monk, PhD, director of Women’s Mental Health in the Department of Obstetrics & Gynecology at New York-Presbyterian/Columbia University Irving Medical Center and professor of medical psychology at Columbia University Vagelos College of Physicians and Surgeons.
The findings of the study appear online in the journal PNAS, the Proceedings of the National Academy of Sciences.


Can Maternal Stress Determine Your Baby’s Gender?

Details of the Study
  • Monk and her team analyzed 27 indicators of psychosocial, physical, and lifestyle stress obtained from diaries, daily physical measurements and questionnaires from 187 seemingly healthy pregnant women, between the ages 18 to 45 years
  • According to the analysis, 17% (32) of the women were psychologically stressed, suffering from clinical depression, high levels of anxiety, and reported they were feeling too stressed
  • About 16% (30) had evidence of physical stress, with relatively higher blood pressure values measured daily and higher caloric intake compared to normal healthy pregnant women
  • The majority of the participants (approximately 67%, or 125) were overall healthy


Findings of Study

  • The study team observed that pregnant women experiencing physical and psychological stress were less likely to have a baby boy
  • Typically, around 105 male babies are born for every 100 female babies. The current study showed an altered sex ratio in the physically and psychologically stressed maternal groups that favored birth of baby girls, with male-to-female ratios of 4:9 and 2:3, respectively
"Other researchers have seen this pattern after social upheavals, such as the 9/11 terrorist attacks in New York City, after which the relative number of male births decreased," says Monk. "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."


Other Impacts of Maternal Stress

  • Women with high physical stress, having higher blood pressure and caloric consumption, had a higher risk of preterm birth than mothers who were not stressed
  • Fetuses of physically stressed women had lower heart rate-movement coupling, an indicator of slower central nervous system development, compared to unstressed healthy women
  • In general, psychologically stressed women had more complications associated with birth than physically stressed women

How Social Support Improves Pregnancy Outcome

  • The more social support a woman receives during pregnancy, the higher the chances of having a male baby
  • Using statistical methods, when social support levels were made similar across the three groups, the stress effects on preterm birth disappeared
  • Around 30% of pregnant women reported psychological stress related to their job or suffering from depression and anxiety during the study. Such women have increased risk of premature birth, which is associated with higher rates of infant mortality as well as physical and mental issues during childhood such as anxiety and attention-deficit hyperactivity disorder (ADHD) among offspring.
  • Effects of mother’s psychological state on the fetus were not analyzed during this study
  • The findings of the study suggest that exposure to high levels of stress increases stress hormones levels such as cortisol in the uterus which can impact the fetus
  • Also, stress can affect the maternal immune system, which in turn impacts neurological and behavioral development in the developing fetus.
In summary, the findings of the study echo the findings of earlier research that poor maternal physical and mental health can affect not only the mother, but her baby as well. Therefore, providing better social support to all moms-to-be during pregnancy can prevent physical and mental stress and improve the baby’s health.

  1. Maternal prenatal stress phenotypes associate with fetal neurodevelopment and birth outcomes - (