Globally, poor and underserved countries tend to have an elevated incidence of infectious disease, often contributing to increased mortality rates. One health issue resulting from this is diarrhea, the 6th leading cause of mortality in developing countries. Because pregnant women are already vulnerable to infections due to an immune system that is rapidly adapting to a developing fetus, they may be more susceptible to diarrhea and the complications that come with it. We sought to identify whether diarrhea during pregnancy was associated with adverse birth outcomes, such as preterm birth and being small for gestational age. We used data from a prospective longitudinal study of maternal influenza immunization of pregnant women and their infants conducted in rural Nepal from 2011-2014. Diarrhea episodes were defined as three or more watery bowel movements per day for one or more days. The chi-square test, two-sample t-test, and log-binomial regression were performed to evaluate baseline characteristics and the association between diarrhea during pregnancy and adverse birth outcomes. From our study, we found that average weight and BMI at enrollment for women with diarrhea was significantly lower than those without diarrhea during pregnancy (47.6kg vs. 48.5kg, p=0.01, 20.72 BMI vs 21.06 BMI, p=0.01) and women with diarrhea during pregnancy were significantly more likely to have small for gestational age infants (42.6% vs. 36.8%, p=0.03). We also found that the incidence of non-live birth, preterm, and low birth weight did not significantly differ between mothers with and without diarrhea. By understanding the risks diarrhea during pregnancy poses for both mothers and infants, we can assess the severity of this problem, and whether or not a possible means of prevention should be prioritized. Further research should examine whether methods to improve weight and BMI during pregnancy prevents diarrheal illness and thus negative birth outcomes.