Qualitative investigations into the emotional needs of expectant fathers have been limited by difficulties with recruitment. This study aimed to unobtrusively obtain insights into fathers' worries during pregnancy by analyzing the content of posts on the Internet forum Reddit. The majority of worries related to infant well-being (50.8%), particularly the potential for perinatal loss (23.0%). Concerns relating to partner well-being and the couple relationship were also common, comprising 17.0% of posts. Several posts related to individual factors, such as apprehension about the father role (16.3%). Finally, situational factors such as work-family conflict accounted for 15.9% of posts. These findings contribute to the growing literature on fathers' experiences of pregnancy and can inform the development of father-inclusive perinatal education.