Pregnancy women who are stressed during the second and third trimester of pregnancy run the risk of preterm birth. Stress may also affect the ratio of boys to girls with the number of boys declining. This is according to a new study published in Europe’s leading reproductive medicine journal Human Reproduction.
While it has been known that stress negatively impacts pregnancy, until now, no investigation has examined the impact of the timing of the stress and the effect stress may have on gender determination.
For the study researchers looked at the medical records of babies born in Chile between 2004 and 2006, around the time of the 2005 Tarapaca earthquake. “Looking at the information on gestational age at the time of the earthquake in a large, unselected group of women, enable us to determine the risk for specific birth outcomes by gestational age of exposure to a stressor, which, because it was a natural disaster, was experienced by all at the same time, although in varying degrees of severity, depending on how close they lived to the epicenter. We were able to capture the developmental periods in which exposure to tress was most detrimental for either sex,” explained Professor Florencia Torche, PhD, and member of the research team.
Women who lived closest to the epicenter during their second and third trimesters had the shortest pregnancies and were at an increased risk of delivering before 37 weeks of gestation. The effect was most notable for female births.
There are usually 51 boys per 100 live births in Chile. After the earthquake the number of male babies dropped to 45. There is a theory that more males are miscarried during stress. “Our findings on decreased sex ratio support this hypothesis and suggest that stress may affect the viability of male births,” said Dr Torche.
Source: MedicalNewsToday, Human Reproduction