Context: While low birth weight is the leading cause of infant mortality and morbidity, the factors influencing low birth weight are not well understood. In particular, the relationship between stressful life events and birth outcomes is unclear. It is important for health care providers to better understand the impact of stress on health outcomes.
Methods: Data from a statewide case-control study of 2,378 Missouri mothers are used to examine the relationship of perceived stress, pregnancy attitudes and major life events as psychosocial risk factors on very low birth weight (i.e., birth weight lower than 1,500 g). Such births are contrasted with moderately low birth weight births (those weighing between 1,500 and 2,499 g) and normal-birth-weight infants (those weighing 2,500 g or more). A stepwise logistic regression model is used to control for all study and control variables.
Results: The risk of very low birth weight is one and one-half times greater if the mother perceived that she "almost always" felt stress during her pregnancy. The regression model confirms that besides perceived stress, several other factors are independently associated with an increased risk of very low or moderately low birth weight. For example, getting back with a husband or partner or experiencing a major injury accident or illness were associated with an elevated risk of low birth weight (odds ratio, 1. 7), as was pregnancy denial (1.4-1.6) and unhappiness about the pregnancy (1.3). On the other hand, a few factors (taking out a mortgage or loan, having a close relative die and having a mistimed pregnancy) appear to have reduced the odds of low birth weight (odds ratio, 0.5-0.8).
Conclusions: Interventions with pregnant women, especially those assessing perceived stress and attitudes toward the pregnancy, have the potential to improve pregnancy outcomes. Additional prospective research with pregnant women on the origins and effects of stress, including the biological effects of stress, is needed.