(dailyRx News) Babies born ahead of their time might need more than tiny clothes. They may also require parents to be more vigilant for signs of developing mental illness in their children.
A recent study has found a variety of strong links between being born early and later developing a range of psychiatric conditions.
One of the highest mental health risks for preemies appears to be bipolar disorder.
Chiara Nosarti, PhD, of the Department of Psychosis Studies in the Institute of Psychiatry at London's King's College, led a study in Sweden to look at how being born early or other birth conditions might affect a person's risk of psychiatric disorders later in life.
Past research has already shown an association between preterm birth and development of schizophrenia, but little had been studied about bipolar disorder, depression and other mental health conditions.
The researchers used data from the Swedish Medical Birth Register for all people born between 1973 and 1985 who were living in Sweden in December, 2000.
The study included data from 1,301,522 people, and the researchers looked at their Apgar scores, the week of pregnancy when they were born and whether their fetal growth rate was normal.
The mental conditions that the researchers looked for included nonaffective psychosis, bipolar disorder, depression, an eating disorder, drug dependency, alcohol dependency or another disorder listed in the psychiatric disorders of the International Classification of Diseases.
They only included people who had been hospitalized for one of these disorders.
The data showed links between having several mental disorders at age 16 or older and having been born earlier than the 37th week of pregnancy.
Preemies born between 32 and 36 weeks were 1.6 times more likely to have nonaffective psychosis and 1.3 times more likely to have depressive disorder. They were also 2.7 times more likely to have bipolar disorder.
Younger preemies showed even stronger links with later development of psychiatric conditions. The risk for those born before the 32nd week of pregnancy was 2.5 times greater for nonaffective psychosis, 2.9 times greater for depression and 7.4 times greater for bipolar.
Preemies born between 32 weeks were also more than three times more likely to develop an eating disorder, and there was a small link (20 to 30 percent) between being born at 32 to 36 weeks and developing a drug or alcohol dependency.
An association between certain psychiatric conditions and a low Apgar score or poor fetal growth was also found. Poor fetal growth is generally measured by a newborn's weight.
Being underweight is considered being "small for gestational age." Those in this category had a slightly higher risk of psychiatric hospitalization with drug and alcohol dependency even after controlling for Apgar score, gestational age, gender, number of siblings and the mother's age, education level and mental health history.
Babies with an Apgar score between 0 and 3 had twice as high a risk for being hospitalized as an adult for depression.
The Apgar score is on a scale of 0 to 10 and is used to assess a newborn's skin complexion (blue to normal), heart rate, reflexes, muscle tone and breathing.
The researchers said it was possible that preterm birth had an association with neurodevelopment problems that contribute to later psychiatric issues, but it's also possible that other factors play a part in the links they found.
For example, this study did not take into account socioeconomic factors, ethnicity or a family history of having preemies, smoking, substance abuse, bacterial vaginosis, bacterial infections in the uterus and viral infections.
Similarly, the link between poor fetal growth and a later risk of drug or alcohol dependency could be altered if the mothers smoked or abused alcohol or drugs.
Another limitation to the study is that only hospitalizations for mental illness were considered, so milder cases of psychiatric conditions could not included.
The study appeared online June 1 in the Archives of General Psychiatry. The research was funded by a Young Investigator Award from the National Alliance for Research on Schizophrenia and Depression.
The authors also receive ongoing support from the National Institute for Health Research Biomedical Research Center for Mental Health at the South London and Maudsley National Health Service Foundation Trust and the Institute of Psychiatry at King's College London. The authors reported no financial conflicts of interest.