Interviewer effects on abortion reporting: a multilevel analysis of household survey responses in Côte d'Ivoire, Nigeria and Rajasthan, India.

Objectives: The analysis aimed to assess the scale of interviewer effects on abortion survey responses, to compare interviewer effects between different question wordings and between direct and indirect approaches, and to identify interviewer and interview characteristics that explain interviewer effects on abortion reporting.

Setting: 2018 Performance Monitoring for Action nationally representative household surveys from Côte d'Ivoire, Nigeria and Rajasthan, India.

Participants: Survey data from 20 016 interviews with reproductive age (15-49) women, selected using multistage stratified cluster sampling. Data from self-administered interviewer surveys and from a sample of health service delivery points that serve the female survey participants were also included.

Primary Outcome Measures: Outcomes were the respondent's own experience of ever 'removing a pregnancy', their closest confidante's experience of pregnancy removal and the respondent's own experience of period regulation.

Results: Substantial interviewer effects were observed, ranging from 7% in Côte d'Ivoire to 24% in Nigeria for pregnancy removal. Interviewer effects for survey questions that were designed to ask about abortion in a less stigmatising way were either similar to (9%-26% for confidante-reporting) or higher than (17%-32% for a question about period regulation) the pregnancy removal question. Interviewer and interview characteristics associated with abortion reporting included respondent-interviewer familiarity, the language of interview and the interviewer's comfort asking questions about abortion.

Conclusion: This study highlights that questions designed to be less stigmatising may increase interviewer effects due to lower comprehension among respondents. Further work is needed to assess question wordings for different contexts. Selecting and training interviewers to ensure comfort asking questions about abortion is important for reproductive health surveys. Challenges for the use of 'insider' interviewers and the management of surveys in countries with high linguistic diversity are also identified.