Objective: The purpose of the study was to assess the effects of the timing of stress during pregnancy on emotional responses and birth outcome. We hypothesized that as pregnancy advanced women would become increasingly resistant to the adverse effects of stress, and so early stress would have more profound effects than later stress.
Study design: Forty pregnant women who had experienced an earthquake during pregnancy or shortly afterward were identified. Using regression analyses we determined whether the timing of the earthquake was related to an affective response to this event and to length of gestation.
Results: The earthquake was rated as more stressful when it occurred early in pregnancy compared with late in pregnancy, and postpartum ratings were similar to first-trimester ratings (r (quad) =.39; P <.05). Stress experienced early in pregnancy was associated with shorter gestational length (r =.35; P <.05).
Conclusions: As pregnancy advances, women become decreasingly sensitive to the effects of stress. This decrease in vulnerability may reflect increasing protection of the mother and fetus from adverse influences during pregnancy.