STOCKHOLM (Reuters Health) Jun 04 - Infants deprived of oxygen at birth due to obstetric complications have a four times higher risk of developing 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 reported these findings in her doctoral thesis at Gothenburg University. The study will soon be published, according to Dr. Dalman.

Using a large sampling of schizophrenics obtained through Sweden's National Birth Register, Dr. Dalman compared 524 schizophrenics in Stockholm with 1,043 nonschizophrenic controls matched for sex and age. After eliminating factors such as hereditary psychosis, she found that the risk of schizophrenia was 4.4 times higher for children who experienced hypoxia during childbirth.

"I've been looking at fetal factors like preeclampsia" and low-weight fetuses, Dr. Dalman told Reuters Health. "If the fetuses are thin or the mothers have preeclampsia, those babies have a doubled risk of schizophrenia later on in life," she said.

"I've also looked at babies born before week 33, and they...have a doubled risk." Children with signs of asphyxia "have a four times higher risk of schizophrenia later in life," Dr. Dalman said.

"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 Dr. Robin Murray, a professor of psychiatry at London's Institute of Psychiatry. "These include poor nutrition and slow growth of the foetus, hypoxia at birth, and neonatal jaundice."

Every tenth child is exposed to some complication during childbirth that could lead to schizophrenia, Dr. Dalman explained, but most do not develop schizophrenia. While the etiology of schizophrenia is largely unknown, the greatest known risk factor is still genetic; children with a schizophrenic parent have a 10-fold increased risk of developing this disease.