The babies of women exposed to the stress of the death of a close relative during the first trimester of pregnancy may have an increased risk of schizophrenia, according to new research findings.
However, the death of a relative during the other trimesters or up to six months before the pregnancy was not associated with an increased risk of schizophrenia, the study found.
Dr Louise Kenny, a senior lecturer in obstetrics and gynaecology at UCC and consultant obstetrician/gynaecology at Cork University Maternity Hospital, is part of the international team of researchers involved in the population-based study.
The peer reviewed paper entitled Higher Risk of Offspring Schizophrenia Following Antenatal Maternal Exposure to Severe Adverse Life Events was published yesterday in the prestigious Archives of General Psychiatry.
"We are not overplaying the risk, but there were more cases of schizophrenia in women exposed to the stress of the death of a relative in the first trimester than we would have expected," she said.
"Overall, the risk is only slightly affected by this work, but it is important because it sheds light on a time in pregnancy and the mechanisms of disease that we know very little about," Dr Kenny told the Health Supplement.
In a cohort of 1.38 million Danish births from 1973-1995, mothers were considered exposed if one (or more) of their close relatives died or was diagnosed with cancer, acute myocardial infarction or cerebrovascular accident up to six months before conception or during pregnancy. Offspring were followed up from their 10th birthday until their death, migration, onset of schizophrenia or June 30th, 2005.
Schizophrenia is a serious, potentially lifelong and disabling condition which is associated with abnormalities of brain structure and function, according to the study.
During the period 1973-1995, the mothers of 36,193 offspring were exposed to illness or death of a close relative. There were 16 mothers who were exposed to the death of a close relative during the first trimester whose offspring subsequently developed schizophrenia - a much higher figure than expected.
Dr Kenny said: "Our research shows that it is when the foetal brain is forming at the start of pregnancy that it is most vulnerable to stress and there is an increased risk of schizophrenia. We are not quite sure how this happens but we feel this is an important paper in terms of shedding light on the causes of schizophrenia."
"The offspring of women exposed to the stress of losing a close relative in the first trimester of pregnancy appear to be at a significantly increased risk of developing schizophrenia as adults," the study noted. "This effect is independent of a range of factors known to influence risk of schizophrenia, such as offspring sex, age, family history of mental illness, place of birth and maternal age. Deaths occurring up to six months before pregnancy and after the first trimester did not have a significant effect on subsequent schizophrenia risk."
Loss of a close relative during the first trimester appeared to have a significant effect on the risk of schizophrenia in the offspring who had no family history of mental illness, but not among those who did have a family history of mental illness in close relatives.