AbstractMany women suffer from new or worsening anxiety during pregnancy. In this pilot study, we investigated the effect of timing and severity of prenatal state anxiety symptoms on reduced birth weight. We hypothesized that: (1) Women with state anxiety symptoms during mid-gestation would deliver newborns with lower birth weight in comparison to participants with symptoms in early gestation and (2) compared to women with lower anxiety symptoms (< 50th percentile), women with medium-to-high state anxiety symptoms (> 50th percentile) would have lower birth weight offspring. The sample consisted of the first 30 pregnant women who agreed to participate in this pilot study. We assessed anxiety symptoms, using the State-Trait Anxiety Inventory during early and mid-gestation. We obtained birth weight from clinical charts. A hierarchical multiple regression showed that, after controlling for covariates, state anxiety symptoms in mid-gestation were associated with lower infant birth weight [F(9, 7) = 20.30, p<.001]. However, birth weight did not differ as a function of the severity of maternal state anxiety [F(1, 23)=.14, p=.71 and F(1, 24)=1.76, p=.20., respectively]. Clearly, our pilot data need replication. Once statistical significance is established with larger samples, it will be informative to examine the clinical significance of those findings.