Research published in The Lancet (September 2000) reviewed tens of thousands of pregnancies to explore whether major life stress might influence the likelihood of birth defects. The authors examined medical records for 3,560 women who experienced significant stressors—events such as the severe illness of a partner or child, or the death of a loved one—either during pregnancy or within the 16 months before conception. Their outcomes were compared with more than 20,000 pregnancies in women who did not experience such extreme stress.
The findings suggested a meaningful difference:
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1.18% of women in the stress group gave birth to an infant with a birth defect, compared with 0.65% in the control group.
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This represented roughly an 80% higher likelihood of a birth defect when major stressors were present.
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The strongest associations appeared when the stress involved the death of an older child during the pregnancy, which was linked with a five-fold increase in risk.
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If the death was unexpected, the association strengthened further, suggesting an eight-fold increase compared to pregnancies without extreme stress.
This study highlights how profound psychological stress may influence pregnancy outcomes, potentially through hormonal, inflammatory, or immune changes that researchers continue to investigate today.
