The Society for Maternal-Fetal Medicine (SMFM) uses social media to increase awareness of the Society and its key programs and to foster community and discussion around perinatal health, especially on Twitter. The influence and role of the SMFM Twitter account in public discourse around issues relevant to pregnancy have not been studied. We sought to evaluate trends in engagement with SMFM on Twitter by analyzing SMFM follower growth and discussion topics on Twitter compared with Facebook and by quantifying public engagement during the SMFM Annual Pregnancy Meeting. This retrospective study analyzed follower growth data from August 2019 to July 2022 for SMFM Twitter (@MySMFM) and SMFM Facebook (@SocietyforMaternalFetalMedicine). We identified the top 10 Tweets and Facebook posts during the study period using Twitter analytics and Facebook data. Popularity of Tweets and Facebook posts was determined by "impressions" and "reach", respectively; these metrics reflect the number of times a post was viewed. To evaluate annual trends in SMFM Twitter engagement, we analyzed data associated with the SMFM Annual Pregnancy Meeting, including the number of Tweets using the hashtag (#SMFM(Year)) and overall impressions for the SMFM Twitter account for each meeting from 2016-20223. The absolute number of new followers for SMFM Twitter and Facebook was similar, but the relative increase and rate of follower growth was higher for Twitter than for Facebook. The Twitter account consistently gained followers while the Facebook account experienced intermittent periods of stagnancy or follower loss. More than half of the top ranked posts on Twitter and Facebook mentioned the COVID vaccine; other popular topics included COVID-19 and abortion. During the SMFM Annual Pregnancy Meeting, Tweets using the meeting hashtag consistently peaked on meeting day 4, coincident with the opening plenary session (mean number of Tweets = 1270 +/- 499). An upward trend in Annual Pregnancy meeting tweets was observed each year until 2021 - the first virtual SMFM meeting. Trends in SMFM Twitter engagement suggest increasing use and popularity of the platform for timely dissemination of pregnancy-related news, guidelines, and research. The reduction in Annual Pregnancy Meeting Tweets and impressions in 2021 and 2022 suggests the potential negative impact of virtual meetings on SMFM member engagement around Annual Meeting content.