Being small at any point in the gestational process—including babies born with a low birth weight—has been linked to a greater risk for the development of schizophrenia and other mental health disorders.
This finding comes from a recent study conducted by Dr. Kathryn Abel and a team of researchers affiliated with the Centre for Women’s Mental Health, Biostatistics/Health Methodology Research Group, the University of Manchester, Karolinska Institutet, Columbia University, New York State Psychiatric Institute and the University of Aarhus.
Birth weight data was reviewed for 1,491,467 infants born in Denmark and Sweden between 1973 and 1986, and the findings revealed that those with a birth weight of less than 2500 g (5.5 pounds) were up to 1.63 times as likely to develop schizophrenia.
Those who had been identified as small at any point in the gestational process also presented with a much higher risk for the development of schizophrenia and any other psychiatric disorders. Specifically, the research suggested that the odds ratio for schizophrenia was 1.34 compared to 1.35 for other psychiatric diagnoses.
Those falling into the category of “small” were defined as being more than two standard deviations less than normal birth weight for a particular gestational age.
Published in the September 2010 issue of the Archives of General Psychiatry, Abel and team noted that “the exact nature of the relationship between birth weight and risk of schizophrenia in adulthood has been debated frequently in the literature but remains unresolved.”
According to background in the published report, most previous studies primarily focused on the World Health Organization low birth weight threshold (less than 5.5 pounds) as it related to schizophrenia but did not conclude or establish a relationship between the two.
Overall, the team reviewed birth year, gender, social class and the presence of mental illness in the mother. By 2005, research findings revealed that 5,445 of the total reviewed had developed schizophrenia, and 57,455 had developed some other form of mental illness.
The risk of schizophrenia and other psychiatric disorders was not only associated with a birth weight of less than 5.5 pounds. The trend for greater risk held true as birth weight decreased across the full range, according to the study.
“In by far the largest sample to date, we have shown that low birth weight is associated with increased risk for adult schizophrenia,” the team noted. “In contrast to those previous studies that have focused on birth weight less than 5.5 pounds, however, we provide evidence that there is no threshold of effect for low birth weight but that risk extends into the normal birth weight range. We also report that other disorders severe enough to result in psychiatric admission or attendance at an outpatient clinic show a similar pattern of a graded association with birth weight.”
In conclusion, the team suggested that there needed to be more extensive research into prenatal causes of mental health disorders with “greater emphasis on the broader links between fetal growth, its control, and brain development.”
Source: Archives of General Psychiatry