There was no evidence of statistical interaction between BMI and race, nulliparity, and diabetes. However, because the interaction between BMI and chronic hypertension was determined to be present, the multivariate analysis was stratified by the presence or absence of chronic hypertension. These results are shown in Table 4. Analysis of the risk factors for women with chronic hypertension indicated that for this population, none of the factors considered were significant predictors of PIH ( p>0.9). Although there was a large loss of power for this analysis, the point estimates for the ORs were generally closer to 1 in contrast to women without chronic hypertension.