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.

Inclusion Criteria:

1. Are pregnant with a gestational age of <20 weeks either by last menstrual period (LMP) and/or ultrasound
2. Are at least 18 years of age
3. Have a visit at a study site during the enrollment period
4. Receive IIV at that visit
5. Have a cell phone with text messaging capabilities
6. Are English or Spanish-speaking
7. Are willing to report via text message through end of pregnancy

Exclusion Criteria:

1. Decision to not continue with pregnancy
2. Any contraindication to receipt of inactivated influenza vaccines
3. Receipt LAIV (live attenuated influenza vaccine) at that visit
4. Previous receipt of IIV in this pregnancy
5. Presence of fever >=100.4F at time of vaccination;
6. Administration of any antipyretic in the 6-hour period prior to vaccination,
7. Stated intent, at time of vaccination, to use prophylactic antipyretics before the development of a fever;
8. Patient only speaks a language other than English or Spanish
9. Patient does not have a cell phone with text messaging
10. Patient's inability to read text messages