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Severe stress during pregnancy linked
to birth defects
Women who are exposed to severe emotional stress during
the first trimester of pregnancy -- such as the death of an older child -- are more likely
to have children with birth defects such as cleft lip and cleft palate, according to a
group of Danish researchers.
However, the overall risk of such birth defects is low,
so even pregnant women who faced life-altering events such as the death of a child still
had a low risk of having a child with birth defects. About 0.65% of all pregnancies
resulted in an infant with such malformations compared with 1.18% of pregnancies in women
under extreme stress, according to the report.
'There has long been a debate about whether emotional
stress causes congenital malformation,' write Dr. Dorthe Hansen of the John F. Kennedy
Institute in Glostrup, Denmark, and colleagues. Some researchers have found associations
between stress during pregnancy and cleft lip and palate, heart defects and other
malformations, while others have not.
Because stress affects not only the nervous system, but
also the cardiovascular, hormonal and immune systems, there is good reason to suspect that
severe emotional stress -- especially during the first trimester when many organs are
forming -- could cause defects, Hansen and colleagues explain.
The researchers examined the medical records of more than
3,500 women who were exposed before or during pregnancy to extreme stress due to a male
partner or older child being diagnosed with cancer, having a heart attack, or dying. The
investigators compared the number of babies born with birth defects with the number born
to a 'control' group of more than 20,000 women who had not been exposed to these events.
Babies born to women who had experienced severely
stressful events in the first trimester of pregnancy were more likely to have defects of
the cranial nerve crest, a structure of cells that is thought to contribute to the
development of the head and face, such as the skull, palate, teeth, nose, parts of the
eyes, ears, throat and heart. These are the structures that have been linked most closely
to stressful events during pregnancy in earlier research.
'The strongest association was seen for women exposed to
the death of an older child during (organ development in the first trimester),' report
Hansen and colleagues in the September 9th issue of The Lancet. These women were almost
five times more likely to have babies with a cleft lip or palate, or a heart defect than
women who were not exposed to such trauma, and if the death of the older child was
unexpected, more than eight times more likely. The likelihood of these defects was
significantly less if the event occurred before the pregnancy or in a later trimester.
No relationship was found between congenital defects and
experiencing the death or severe illness of a male partner during pregnancy, the authors
report. They note, however, that the number of cases in which this happened was much
smaller than the number in which women lost older children. But it is also possible, they
add, that 'severe life events in children may on an average cause more stress in the women
than severe life events in partners.'
Hansen and colleagues also report that no relationship
was found between extreme stress and other kinds of congenital defects. |
