Authors
Summary
Objective: To examine the quality and patterns of miscarriage reporting across different surveys administered in Great Britain (GB). Design: Comparative descriptive analysis of pregnancy and miscarriage data collected by four surveys following different methodological approaches including cohort, cross-sectional and household panel surveys. Setting: Great Britain Population or Sample: 29,426 pregnancies reported by 12,648 women in 1970 British Cohort Study (BCS70), Next Steps, Understanding Society (UKHLS), and the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3). Methods: We compared the formulation of pregnancy and miscarriage questions across the surveys, as well as several miscarriage and pregnancy prevalence indicators to understand which approaches may lead to improved miscarriage reporting. Main Outcome Measures: Using self-reported information on past pregnancies from each survey, we examined the average number of reported pregnancies, the proportion of women reporting one or more miscarriage(s), the distribution of all pregnancy outcomes and more specifically the proportion of miscarriages among all pregnancies, and the age-specific miscarriage prevalence. Results: The share of miscarriages among all reported pregnancies ranged between 14 and 21%, and between 18 and 24% of all women reported at least one miscarriage. While the prevalence of miscarriage rates was similar across surveys, UKHLS systematically reported the lowest prevalence, while Next Steps recorded the highest. The prevalence of miscarriage substantially increased after age 34 in all surveys, however with disparities across surveys for pregnancies in the early 40s. Conclusions: Overall, GB surveys provide miscarriage estimates consistent with previous clinical studies but with some heterogeneity across surveys. These differences can be attributed to incomplete collection of pregnancy histories and variation in the age and cohort composition of study populations. Researchers should pay careful attention to questionnaire design, and possible recall issues when using survey data for miscarriage research. Providing clear definitions of miscarriage may reduce heterogeneity in responses.
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Open Access
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