Lack of Oxygen at Birth Increase Risk of Schizophrenia

June 2, 2001 - A research report that came out today suggested that newborns who are deprived of oxygen at birth due to obstetric complications are at four times greater risk of schizophrenia later in life than other children, new research suggests.

Many different obstetric complications during pregnancy and delivery are associated with a future risk of schizophrenia, said Dr. Christina Dalman, a psychiatrist who recently published her doctoral thesis at Gothenburg University.

A growing body of evidence links the disease with complications at birth. ``I've been looking at fetal factors like preeclampsia or if the fetuses are thin,'' Dalman said, ``and I've found that if the fetuses are thin or the mothers have preeclampsia, those babies have a doubled risk of schizophrenia later on in life. I've also looked at babies born before week 33 and they also have a doubled risk. And, then I've been looking at signs of asphyxia and those children have a four times higher risk of schizophrenia later in life.''

Preeclampsia strikes about 5% of first-time mothers, and occurs less frequently among other pregnant women. Characterized by high blood pressure, swelling and protein in the urine, preeclampsia sometimes progresses to eclampsia, a life-threatening condition marked by convulsions. ``Dr. Dalman's work is among the most impressive of any research in this area and puts beyond doubt the evidence that a range of factors during pregnancy and birth can increase the later risk of schizophrenia,'' said Robin Murray, a professor of psychiatry at London's Institute of Psychiatry. ``These include poor nutrition and slow growth of the foetus, hypoxia (lack of oxygen) at birth, and neonatal jaundice.'' Every 10th child is exposed to some complication during childbirth that could lead to schizophrenia, explained Dalman, but most do not develop the illness. The origins of schizophrenia are largely unknown, but the greatest known risk factor is genetic, with a 10 times increased risk for children with one parent with the illness.

Dalman was able to take advantage of a large sampling of people with schizophrenia in Sweden because of the country's unique registering systems. The National Birth Register, for instance, contains information on all children born in Sweden, about 100,000 every year. The researcher was able to compare 524 schizophrenic persons in Stockholm with 1,043 people of the same sex who were born about the same time. After eliminating factors such as hereditary psychosis, Dalman found that the risk for schizophrenia was 4.4 times higher for children who suffer from hypoxia during childbirth.

Research Paper: Signs of asphyxia at birth and risk of schizophrenia. Population-based case-control study.




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