Physical and mental stress on a pregnant woman may increase the risk of stillbirth, a new study suggests.

The study involved more than 2,000 U.S. women who were surveyed 24 hours after a delivery or after a stillbirth. (About 600 women who’d experienced a stillbirth were recruited to take part in the study, along with about twice as many women who had delivered.)

In the study, women who said they had experienced five or more stressful life events in the past year, such as losing a loved one or their job, were 2.5 times more likely to have a stillbirth compared with women who experienced no stressful life events in the past year.

The finding “reinforces the need for health care providers to ask expectant mothers about what is going on in their lives, monitor stressful life events and to offer support as part of prenatal care,” said study researcher Marian Willinger, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), which funded the study.

However, stressful life events were common, and most women who were stressed did not have a stillbirth.

Among women who carried their baby to delivery, 75 percent (1,015 women) experienced a stressful life event in the past year, compared to 83 percent of women who had a stillbirth (503 women), the researchers said. About one in ten women who delivered, and one in five women who had a stillbirth, experienced five or more stressful events.

A stillbirth is defined as the death of a fetus after 20 or more weeks of pregnancy. For every stillbirth in 2006, there were 167 live births, according to the Centers for Disease Control and Prevention.

Women were especially at high risk of stillbirth if they were in a physical fight in the past year, or if they had a partner go to jail.

“This is a first step toward cataloguing the effects of stress on the likelihood of stillbirth and, more generally, toward documenting how pregnancy influences a woman’s mental health and how pregnancy is influenced by a woman’s mental health,” said study researcher Uma Reddy, also of NICHD

The study is published in the American Journal of Epidemiology.

Previous studies have linked stress in pregnancy to an increased risk of preterm birth, or to having a baby with a low birth weight.

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