Help for children born preterm might need to extend to their sibs

An unprecedented study of preterm birth suggests that only some of the problems previously associated with preterm birth are actually caused by preterm birth itself.

Brian D'Onofrio

Brian D’Onofrio

The study, for me, is an example of how ambitious, well-designed studies can shred conventional wisdom — ideas that otherwise would make sense and might even be supported by earlier research that had limitations surmounted by newer studies.

From the IU news release:

The new study by Indiana University Bloomington researchers confirms the strong link between preterm birth and the risk of infant and young adult death, autism and ADHD. But it also suggests that other threats that have been closely tied to the issue, such as severe mental illness, learning problems, suicide and economic woes, may instead be more closely related to other conditions that family members share.

“The study confirms the degree to which preterm birth is a major public health concern and strongly supports the need for social services that reduce the incidence of preterm birth,” said lead author Brian D’Onofrio, associate professor in the Department of Psychological and Brain Sciences at Indiana University Bloomington. “Yet, the findings also suggest the need to extend services to all siblings in families with an offspring born preterm. In terms of policy, it means that the entire family, including all of the siblings, is at risk.”

(Visit my Tumblr blog for cool pics and a video of a giant limestone brain as the Department of Psychological and Brain Sciences celebrates its 125th anniversary.)

The study is thought to be the largest population-based study of preterm births to date. The sheer number of children in the study — 3.3 million born in Sweden between 1973 and 2008 — allowed the researchers to examine relatively rare conditions, such as birth at 25-30 weeks, schizophrenia and autism. The study also is unique for comparing preterm infants to their non-preterm siblings and cousins.

From the news release:

The problem with previous studies that compared preterm infants to unrelated non-preterm infants, D’Onofrio said, “is that preterm birth is associated with a lot of other factors that are also predictive of poor outcomes in the offspring. So you are not sure if preterm birth or all these other factors actually cause these harmful outcomes. Trying to tease apart what is due to preterm birth or everything that goes along with preterm birth is very difficult.”

Comparing siblings is a way of controlling for and holding constant everything those siblings share: mothers and fathers, socio-economic status, and some genetic factors.

Here is a list of the information tapped, to give you a sense of the volume of data crunched for this study: The Medical Birth Registry, which includes information on more than 99 percent of pregnancies in Sweden since 1973; the Multi-Generation Registry, which contains information about biological relationships for all individuals living in Sweden since 1933; the Migration Register, which supplies information on dates for migration in or out of Sweden; the Cause of Death Register, which includes information on dates and causes of death since 1958; the Patient Registry , which provides diagnoses for all inpatient hospital admissions since 1973 and outpatient care since 2001; the National Crime Register, with detailed information about all criminal convictions since 1973; the National School Register, which includes grades in all subjects for all students at the end of grade 9 since 1983; the Education Register, with information on highest level of completed formal education through 2008; and the Longitudinal Integration Database for Health Insurance and Social Studies, which contains yearly assessments of income, marital status, social welfare status and educational level for all individuals aged 15 and older since 1990.

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