Using a health observance event to raise awareness: An assessment of World Birth Defects Day.

World Birth Defects Day (WorldBDDay), observed annually on March 3, was launched in 2015 to advocate for public health surveillance, research, and prevention of birth defects, along with improved care and treatment for affected individuals. Following its fifth observance in 2019, we assessed WorldBDDay by analyzing: (a) engagement and content of over 2000 WorldBDDay posts on Facebook, Twitter, and Instagram; (b) interview responses from 9 WorldBDDay charter (founding) organizations on their perceptions of strengths and areas for improvement for WorldBDDay; (c) survey responses from 61 WorldBDDay 2019 partner (participating) organizations on their WorldBDDay 2019 activities; and (d) post-2019 social media engagement. Most social media posts (60%) occurred from organizations using Twitter (80% vs. 14% for Instagram and 6% for Facebook), although posts from individuals had higher levels of engagement (e.g., likes and comments). The highest engagement occurred for posts focused on general awareness, prevention, or events. Charter organizations reported the need for existing and new partner engagement, including a designated WorldBDDay contact for regular communication and coordination of activities and prepared prevention-focused messaging. Partner organizations reported using the WorldBDDay toolkit, especially key messages and social media tips, and suggested expanding the toolkit with relevant resources. Post-2019 Twitter engagement was lower than 2019 WorldBDDay (peak event) but showed similar reach to WorldBDDay events prior to 2019. Our assessment identified WorldBDDay health observance events as an important tool to support knowledge dissemination and global community engagement around birth defects. Moving forward, engagement with more individuals and organizations may improve the reach of WorldBDDay.