This is a pilot, prospective, randomized, open-label clinical trial. During the study, pregnant women will be randomized (1:1) to receive co-administration of a single intramuscular (IM) 0.5 mL dose of US-licensed inactivated influenza vaccine (IIV) and a single intramuscular (IM) 0.5 mL dose of US-licensed Tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine adsorbed (Tdap) or sequential administration of the vaccines (IIV followed by Tdap ~ 21 days later). Vaccines will be administered by licensed study personnel.