Recruitment prior to conception for pregnancy studies: a systematic review and meta-analysis

This review provides a quantitative synthesis of recruitment and retention patterns in preconception research, addressing a critical but understudied period to improve maternal and child health. We found that participant characteristics, recruitment strategy, and study design substantially influence recruitment rates, preconception attrition, and pregnancy retention, with important implications for feasibility assessment, anticipated loss to follow-up, and sample size estimation. Our findings highlight the need for recruitment of diverse populations and methodological tools tailored to preconception research. These findings offer empirically grounded parameters to support the design of more efficient, inclusive, and adequately powered preconception and pregnancy-related studies.