My sister is four months pregnant. Her husband died suddenly last month, and we’ve all been shocked and devastated. I’ve heard that traumatic events during pregnancy increase the child’s risk of developing schizophrenia. Is that true?

It is well-established in dozens of studies that complications during pregnancy and delivery may increase the risk of schizophrenia later on in life in the offspring. However, most of these complications refer to conditions that adversely affect the brain development of the fetus, such as exposure of the pregnant woman to a viral infection, severe nutritional deficiencies (starvation), alcohol or drug intake, bleeding, low oxygen availability, immunological problems (such as Rh incompatibility) and serious medical illness.

The most vulnerable period of pregnancy where such adverse events to the brain of the fetus may increase the risk for schizophrenia is the second trimester – months four, five and six. The reason is that critical growth and development events occur during the second trimester, such as neuronal migration (the movement of brain cells to their proper locations), differentiation (when cells mature to form a specific task), and pruning (removal of unneeded brain cells). Disruption of any of those developmental processes can affect the infrastructure of the brain and may lead to psychiatric illness later in childhood (such as autism) or in adulthood (such as schizophrenia or other psychotic disorders).

So what about your sister losing her husband during pregnancy, especially since this stressful event occurred during her second trimester? Theoretically, severe stress during pregnancy may have a disruptive effect on the fetal brain development due to the increased levels of cortisol and other stress-related biological changes. There is only one published report (from Finland) where the risk of schizophrenia was found to increase if the husband died during pregnancy. However, in my opinion, normal grief should not be too risky unless it is prolonged and unresolved. Research on this subject (exposure to stress early in life) actually points to an increase in the risk of depression and stress -reactivity rather than psychosis.