[Anxiety during pregnancy, prematurity, and low birth weight: a systematic literature review].

The purpose of this systematic literature review was to examine publications that had investigated the effect of anxiety on prematurity and/or low birth weight. The PubMed, BVS, CINAHL, and HEALTHSTAR databases, published from 1966 to 2006, were tracked using the following key words: "anxiety", "pregnancy", "low birth weight", and "prematurity". Thirteen studies were found: 11 cohorts, 1 cross-sectional, and 1 case-control. Most studies (7/13) were conducted in the United States. The most reliable results came from four studies, whose strengths were: exclusion of adolescents and/or women older than 34 years, studies that analyzed anxiety during the second and/or third trimester of pregnancy, used validated scales to measure anxiety, kept loss-to-follow-up rates below 30%, and applied adequate control of confounders. Anxiety during pregnancy was associated with prematurity and/or low birth weight in eight studies. Odds ratios and relative risks varied from 1.08 to 2.31. Carefully designed and well-conducted studies are still needed to clarify the relationship between anxiety during pregnancy, prematurity, and low birth weight considering that the accumulated evidence remains controversial.