Background: Social media platforms provide new possibilities within health research. With Facebook being the largest social network in the world, it constitutes a potential platform for recruitment and data collection from women of reproductive age. Women in Denmark and in other Western countries postpone motherhood and risk infertility due to their advanced age when they try to conceive. To date, no study has explored Danish women’s reflections on the timing of motherhood within a social media setting. Objective: The aim of this study was to explore the challenges and opportunities of using Facebook as a platform for qualitative health research in Danish women of reproductive age. Methods: This study was a qualitative study based on 3 online focus groups on Facebook with 26 Danish women of reproductive age discussing the timing of motherhood in January 2020. Results: Conducting online focus groups on Facebook was successful in this study as the web-based approach was found suitable for developing qualitative data with women of reproductive age and made recruitment easy and free of charge. All participants found participating in an online focus group to be a positive experience. More than half of the women participating in the online focus groups found it advantageous to meet on Facebook instead of meeting face-to-face. Conclusions: Conducting online focus groups on Facebook is a suitable method to access qualitative data from women of reproductive age. Participants were positive toward being a part of an online focus group. Online focus groups on social media have the potential to give women of reproductive age a voice in the debate of motherhood.