Previous studies have suggested that prenatal stress may be associated with a spectrum of adverse pregnancy outcomes, including preterm birth and low birth weight (reviewed in Hobel et al, 2008). A recent study from Danish researchers has investigated the impact of psychological stress on risk for stillbirth.

In this prospective cohort study, data from a total of 19,282 singleton pregnancies were collected and analyzed. Psychological stress during pregnancy was measured at 30 weeks of gestation using the 12-item General Health Questionnaires (GHQ). Women with intermediate levels of psychological stress (scores of 7-11) were used as the reference group. Scores of 0-6 were defined as a low level of psychological stress and scores of 12-36 indicated the highest levels of stress.

Stillbirth (fetal death after 28 weeks of gestation) occurred in 66 pregnancies (3.4%). Compared to women with intermediate levels of psychological stress during pregnancy, women with higher levels of stress had an 80% increased risk of stillbirth (relative risk = 1.8). Adjusting for certain confounding variables, including maternal age, parity, maternal pre-pregnancy body mass index, smoking, alcohol and caffeine intake during pregnancy, marital status, and education level failed to change the findings. In addition, the results remained unchanged after excluding women with preterm deliveries or other complications during pregnancy (including diabetes, hypertension, vaginal bleeding).

This is the first study to examine the effect of antenatal psychological stress on risk of stillbirth, indicating that more extreme levels of stress are associated with a nearly twofold increase in the risk of stillbirth. The authors speculate that stress may increase the risk of stillbirth and other adverse pregnancy outcomes in different ways. Psychological stress, depression and anxiety are all associated with high levels of stress hormones, including catecholamines. In animal studies, it has been demonstrated that high catecholamine levels have been associated with decreased placental blood flow and fetal asphyxia. While certain behaviors like smoking may increase the risk of stillbirth and are more common in women who experienced higher levels of stress, the researchers were able to carefully control for these variables and demonstrated no evidence of confounding from these variables.

Ruta Nonacs, MD PhD

Wisborg K, Barklin A, Hedegaard M, Henriksen TB. Psychological stress during pregnancy and stillbirth: prospective study. BJOG. 2008 Jun;115(7):882-5.

Hobel CJ, Goldstein A, Barrett ES. Psychosocial stress and pregnancy outcome. Clin Obstet Gynecol. 2008 Jun;51(2):333-48.