Stressful First Trimester found to cause Premature Birth, Less Male Babies?
No other study has explored the timing and effects of early stress in pregnancy, though common wisdom tells that it is not good. Also, the fact that early stress reduces the possibility of having male babies is bit surprising to experts. The study also found out that stress itself is more damaging than other factors, like poverty, in pregnancy.
In the study, researchers studied birth certificates of babies born between years 2004-2006. Information like gestational age, sex, weight and medical attention and mother’s residence, parity and marital information are collected and analyzed. These gave important information on whether how close the mothers were to the epicenter when the earthquake happened. Of course, the selected participants are largely unselected and mixed. In the count, it is estimated that the birth rate in Chile at that time amounted to 200,000 per year.
Because the earthquake’s magnitude is ‘quite disastrous’ 7.8 magnitude and its epicenter is near several towns in Chile, it is expected that many people including pregnant women will experience tremendous stress during that period. Analysis shows that pregnant women who are in their second month of pregnancy at that time cut their pregnancies by as much as 1.3 days short compared to others who are largely unaffected.
Those who are in their third month cut their terms by almost two days short, and preterm births rose more than 3.4 percent – at the rate of nine deliveries per 100 births. This is higher than the average six per 100 women at that time in Chile. Risk of preterm birth increased significantly when stress happened during second month of pregnancy by as much as 3.9 percent. The earthquake also affected the sex ratio of newborns as the normal ration of 51 boys in every hundred was reduced to 45, resulting to more females being born than males.
Based on this evidence, it is clearly established that stress at first trimester can influence the state of pregnancy till childbirth. Though the research is based on a natural disaster, the same amount of stress can still be experienced by pregnant women (including those who don’t have any idea that they are pregnant) facing unemployment, harassment, unreasonable work demands, abuse from spouse and sexual abuse.
Regarding the change in sex ratio, it’s not that stress automatically changes the fetus’ sex from female to male. Previous research explained that stressed women are more likely to miscarry male fetuses than females, largely because males grow larger and require more resources from the mother. Intense stress consumes considerable resources from the mothers, and in hard times, the body will prioritize the mother’s well-being more than the growing fetus, thus causing spontaneous abortion.
Researchers recommend that although it’s not possible to completely avoid natural disasters, outside sources of stress from work, family and relationships should be limited as much as possible especially during the early months of pregnancy.
The study is available in the journal Human Reproduction, the leading reproductive medicine journal in Europe, this month of December.
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