– EN Fitness & Wellbeing – Women who are stressed during pregnancy are more likely to have girls, researchers report.
Academics at Columbia University and NewYork-Presbyterian Hospital have examined 27 indicators of stress collected from questionnaires, diaries, and daily physical assessments of 187 otherwise healthy pregnant women, aged between 18 and 45.
Around 17 per cent of participants were psychologically stressed, with high levels of depression, anxiety, and perceived stress, while another 16 per cent were physically stressed, with relatively higher daily blood pressure and greater caloric intake compared with other healthy pregnant women. The majority of those analysed were healthy.
“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,” said study leader Dr. Catherine 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.”
On average, around 105 males are born for every 100 female births. But in this particular study, the sex ratio in the physically and psychologically stressed groups favoured girls, with male-to-female ratios of 4:9 and 2:3, respectively.
The researchers also claimed that physically stressed mothers, with higher blood pressure and caloric intake, were more likely to give birth prematurely than unstressed mothers, and psychologically stressed mothers had more birth complications than physically stressed mothers.
Elsewhere in the study, Dr. Monk and colleagues noted that what most differentiated the three groups was the amount of social support a mother received from friends and family. For instance, the more social support a mother received, the greater the likelihood of her having a male baby.
Full study results have been published in the journal PNAS.