Antenatal care (ANC) remains an important contact point on the continuum of care for mothers and children in low- and middle-income countries. In Tanzania, the proportion of pregnant women completing at least four ANC visits (ANC-4) dropped from 70% to 43% between 1999 and 2010. To identify potential causes of the decline in the number of ANC visits, we conducted qualitative research at 18 health centres in Morogoro Region, exploring providers’ communication about ANC visits and clients’ and providers' perceptions of changes in ANC services and barriers to completing four visits. We also observed counselling messages delivered during 203 ANC consultations. Our results indicate that provider communication about ANC visit recommendations is inadequate, and confusion exists among clients about when and how often they should attend. Participants highlighted how the scale up of Prevention of Mother-to-Child Transmission, with routine human immunodeficiency virus testing for women and their male partners, presents additional barriers for some women. Changes to the timing and content of ANC services following the adoption of the Focused ANC model was described by participants as changing women’s perceptions and decisions in how they utilize ANC services. In particular, condensed delivery of technical interventions fostered a sense among clients that multiple visits are unnecessary. Other barriers that may contribute to declining ANC-4 include changing norms about family planning and birth spacing, out-of-pocket costs for clients and informal practices adopted by health facilities and providers such as turning women away who attend early in pregnancy or are not accompanied by male partners. Further research is needed to determine the role and extent that these barriers may be contributing to declining ANC-4. Issues of poor communication, supply inadequacies and informal practices, deserve immediate attention from the health system.