Severe stress during pregnancy linked to birth defects
2000-09-10 17:52
New York - 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.
öThere has long been debate about whether emotional stress
causes congenital malformation,ö 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.
öThe strongest association was seen for women exposed to
the death of an older child during (organ development in the
first trimester),ö 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 ôsevere life events in children
may on average cause more stress in the women than severe life
events in partners.ö
Hansen and colleagues also report that no relationship was
found between extreme stress and other kinds of congenital
defects.