Objective To explore general practitioners' (GPs') perceived indicators of vulnerability among pregnant women in primary care. Design A qualitative study with semi-structured in-depth focus group interviews. Setting General practices located in a mixture of urban, semi-urban and rural practices throughout the Region of Southern Denmark Subjects Twenty GPs. Main outcome measures Through qualitative analysis with systematic text condensation of the interview data, the following themes emerged: (1) obvious indicators of vulnerability-i.e. somatic or psychological illnesses, or complex social problems and 2) intangible indicators of vulnerability - i.e. identification depended on the GPs' gut-feeling. From the GPs' perspective, the concept of vulnerability in pregnancy were perceived as the net result of risk factors and available individual and social resources, with a psychosocial etiology as the dominant framework. Conclusions The GPs demonstrated a broad variety of perceived indicators of vulnerability in pregnancy; most importantly, the GPs were aware of a group of pregnant women with intangible vulnerability mainly representing low resilience. Despite not fitting into the GPs' perceived concept of vulnerability, the GPs had a strong gut feeling that these women might be vulnerable. Misjudging the resources of pregnant women due to their physical appearance could delay the GPs' identification of vulnerability. Future studies should explore the challenges GPs experiences when assessing vulnerability among pregnant women.