Background: While WhatsApp groups can be a tool to extend antenatal communication out of the clinic, regular digital contact does not necessarily indicate satisfaction or clinical efficacy. Objective: To describe the engagement patterns, verbalised experiences, perceived usefulness, supportive exchanges and challenges in a WhatsApp antenatal group linked to a hospital. Methods: This is a qualitative descriptive study where data was obtained through secondary analysis of textual data from the official Antenatal Support Group of the University of Port Harcourt Teaching Hospital, Nigeria, from 4th August 2022 to 25th August 2023. There were 679 unique sender labels in the corpus, and 12,409 messages. Relevance filtering and data cleaning resulted in 4,286 substantive messages being managed and analysed within NVivo by a multidisciplinary team using the six-phase thematic approach of Braun and Clarke. Message counts were not considered prevalence estimates for the participants, but descriptive features of the corpus. Results: Seven themes emerged: "visible engagement," "expressed appreciation and perceived usefulness," "access to antenatal information," "emotional reassurance," "peer learning," "linkage with facility-based care," and "challenges with platforms. The workbook included 339 messages that had to do with satisfaction, with 186 unique sender labels. These were indicators of text satisfaction rather than verified text satisfaction scores. No change in anxiety, attendance, or maternal outcomes were found in the data. Conclusion: The message corpus indicates that the moderated WhatsApp group could be a valuable auxiliary communication, reassurance and peer interaction channel during pregnancy. Further research is needed with validated measures and clinical outcomes to infer effectiveness.