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Ask the Experts

Question:

Has any research been done to see if there is a link between stressful births (delivery of a baby through delayed caesareans, possible hypoxia or trauma)and schizophrenia?

Answered by: Cheryl Corcoran

My colleague Dr. Alan Brown has written a wonderful review of risk factors for schizophrenia, which includes a section on “obstetric complications”, which is the technical term which includes the “stressful births” you ask about, though also includes complications during pregnancy, and abnormal fetal growth and development before the birth itself.

Here are some of the main points of Dr. Brown’s review, entitled “The environment and susceptibility to schizophrenia”, published in 2011 this year in the journal “Progress in Neurobiology”: Early meta-analyses in the 1990’s suggested “obstetric complications” doubled the risk for schizophrenia, i.e. prematurity, premature rupture of membranes, or the need for resuscitation or incubator use.

In a later “meta-analysis” in 2002, emergency C-sections were found to increase the risk of schizophrenia threefold.

These meta-analyses (which are analyses of many studies together) support that “stressful births” are a risk factor for schizophrenia.

However, as Dr. Brown points out, there are caveats to keep in mind. An association of obstetric complications and schizophrenia may be “spurious” in that both are related to a “confound” i.e. an unknown third factor. (Consider how eating ice cream and sunburn may be associated, even though one is unlikely to cause the other). Also, many studies rely on “maternal recall” years later, after a diagnosis of schizophrenia is made in the offspring, when mothers may have been thinking about what may have caused their child’s illness, and more likely to recall early adverse events than other mothers of children without mental illness.

The mechanism of how obstetric complications may increase risk for schizophrenia is unclear. One feature common to most of the “obstetric complications” identified as at least doubling the risk for schizophrenia is that they involve “hypoxia” during birth, such that the newborn has some period of time of getting insufficient oxygen.

In animal models, rats exposed to hypoxia during birth have features similar to the biology of schizophrenia, including changes in dopamine release in the striatum in response to amphetamine or stress, enlarged ventricles and smaller hippocampal volumes. So hypoxia is a plausible mechanism for how stressful birth may lead to later onset of schizophrenia.