Limitations
Our initial expectation of a larger effect size (5 points increase) led to an underpowered sample size to detect smaller gains in knowledge. Our participants were all receiving routine antenatal care, where they were likely hearing similar perinatal health messages to the ones included in the SAS videos. Other significant limitations of this study were the real-world challenges associated with testing a mHealth intervention in a setting where internet access can be unreliable, the turnover of cell phones and contact numbers is high, and mothers may be sharing cell phones with their partners. This led to a larger-than-anticipated loss to follow-up in this study and negatively impacted our ability to detect an effect of the SAS intervention. We also did not collect data on the parity of this study’s participants. Finally, we were constrained by the method of measuring knowledge in this study. Due to literacy barriers, the knowledge survey had to be administered verbally by our research assistants. The inability to administer the knowledge surveys without human intervention (ie, digitally) meant that we could not exclude the possibility that interviewers collecting survey data may have inadvertently helped the participants. This potential limitation is supported by the relatively high knowledge scores we observed across all participants.