As is typical in Web-based survey research, we employed multiple attention checks and quality screens in our surveys . Attention checks confirmed that Web-based survey respondents were reading questions carefully and thoroughly. Quality screens attempted to confirm self-reported pregnancy and smoking status and confirmed that respondents spent an adequate amount of time completing the survey and were not simply checking response boxes as rapidly as possible (eg, selecting the same column repeatedly in a grid). Qualtrics Panel suggested using one-third of the median time to complete the survey as the cut-off point to determine whether respondents rushed through the survey, so we applied this criterion to every survey platform as a part of the quality screens. By platform, 0% (0/9) of respondents in mTurk, 13% (1/8) of respondents in Qualtrics Panel, 28.9% (31/107) of respondents in Soapbox Sample, and 16.9% (30/178) of respondents in Reddit did not pass the time-quality screens.