U.S. obstetrician/gynecologists play a critical role as vaccinators of pregnant women. However, little is known about their current immunization practices. Thus, study objectives were to determine (1) practices related to assessment of vaccination status and vaccine delivery for pregnant patients; (2) barriers to stocking and administering vaccines; and (3) factors associated with administering both influenza and tetanus, diphtheria, and acellular pertussis (Tdap) vaccines.