Is there a preferred gestational age threshold of viability? A survey of maternal-fetal medicine providers

Objective. To characterize variation and factors associated with the perceived gestational age for the threshold of viability among maternal-fetal medicine (MFM) providers. Methods. We performed a web-based online survey of 1375 MFM providers. For this secondary analysis, a subset of survey questions targeted toward perceptions of the limit of viability was analyzed to identify how the respondents viewed the optimal threshold of viability gestational age. Comparative statistics were performed to assess various characteristics that influence the perceived threshold of viability. Results. Five hundred and eight providers (37%), representing all 50 states and 13 countries, responded to the survey. The reported threshold of viability varied among survey respondents: 22 weeks, 2.0%; 23 weeks, 37.2%; 24 weeks, 55.3%; 25 weeks, 3.4%; and 26 weeks, 2.2%. No significant differences were noted in the reported threshold of viability with respect to practitioner age (<50 years old vs. ≥50 years old, p = 0.42), nursery availability (level III vs. other, p = 0.46), and years in practice (<10 years vs. ≥10 years, p = 0.86). Significant differences in the reported threshold of viability were noted with respect to practitioner gender with males tending to have a lower gestational age threshold than females (p = 0.005). Significant differences were also noted among practitioners from academic vs. community/private practice settings (p = 0.008). A logisitic regression model, adusting for both gender and practice setting, revealed that male gender was independently associated with selection of a threshold of viability less than 24 weeks of gestation: male gender OR 1.8 (95% CI 1.3-2.7, p = 0.002); academic practice setting OR 1.1 (95% CI 0.8-1.6, p = 0.50). Conclusions. Perceived threshold of viability among MFM providers varies with the majority of practitioners identifying 23-24 weeks of gestation. Significant difference, however, exists between practitioner genders.