This study analyzed the effects of the announcement and publication of the 2019 Public Charge Rule on participation of the special supplemental nutrition program for women, infants, and children (WIC) among pregnant immigrants. A difference-in-differences approach was used to analyze the changes in prenatal WIC participation before and after the 2019 Public Charge Rule announcement and publication among immigrants relative to US natives. We identified 17,623,683 live singletons born in a hospital from 2015 to 2019. Compared to US natives, the odds of prenatal WIC participation among immigrants were 11.4% lower after the 2019 Public Charge Rule announcement, and 19% lower after the final rule was published. The results of this study suggest that pregnant immigrants may decide not to participate in the WIC program due to the fear of jeopardizing their immigration status after the announcement and publication of the 2019 Public Charge Rule.