BackgroundOur objective was to investigate: (1) the proportion of influenza vaccination, attitudes, and barriers among pregnant women, (2) the proportion of obstetrics and gynecology (OBGYN) doctors who routinely recommend influenza vaccination in pregnant women, and (3) the influencing factors in Korea, during the flu season of 2019-2020, following the introduction of free influenza vaccination program for pregnant women.MethodsTwo separate anonymized questionnaires were developed for pregnant or postpartum women and physicians, and distributed to public or private healthcare centers and clinics, in South Korea. The proportions of women who received influenza vaccination during pregnancy and OBGYN doctors who routinely recommend influenza vaccine for pregnant women were analyzed. Independent influencing factors of influenza vaccination and OBGYN doctors’ routine recommendation for pregnant women were analyzed using multivariate logistic regression analysis, respectively.Result The self-reported proportion of influenza vaccination during pregnancy among 522 women was 63.2%. Independent factors influencing maternal influenza vaccination were ‘(ever) received information about influenza vaccination during pregnancy’, ‘information obtained from OBGYN doctors’, and ‘2nd/3rd trimester or postpartum period’ (OR 8.988, 95% CI 4.21–19.188, p < 0.001, OR 2.611, 95% CI 1.705-3.998, p < 0.001 and OR 3.082, 95% CI 1.508–6.297, p < 0.001, respectively).In 372 OBGYN doctors, the proportion of doctors with the routine recommendation of influenza vaccine for pregnant women was 76.9%. Independent factors affecting the routine recommendation were: 1) affiliation with private hospital or clinic (OR 4.508, 95% CI 2.225–9.133, p<0.001); 2) awareness of guidelines (OR 3.153, 95% CI 1.118–8.894, p=0.03); (3) awareness of 2019 National free influenza vaccination program for pregnant women (OR 4.955, 95%CI 2.377–10.329, p<0.001). For a future recommendation of influenza vaccine for pregnant women, the guidelines proposed by the government or public health care [108 (46%)] and academic committees [59 (25%)] were most commonly chosen by OBGYN doctors.Conclusion This study demonstrated that providing information about maternal influenza vaccination and the recommendation by OBGYN doctors are crucial for increasing the vaccination coverage in pregnant women.