In this study, the investigators will prospectively assess fever rates and other adverse events in pregnant women after administration of inactivated influenza vaccine (IIV) using text messaging. The investigators hypothesize that women <20 weeks gestational age who receive IIV will be willing to enroll in a text messaging-based vaccine adverse event monitoring program and will use it to report fever in the post-vaccination period as well as continue to text pregnancy-related outcomes through the end of their pregnancy.