Recruitment and retention of participants in TB clinical trials are critical challenges that may impact the efficiency and cost of drug development. In pregnant populations—particularly given post-delivery mobility—complete collection of maternal, pregnancy, and birth outcome data is often difficult. Recruitment and retention strategies should be tailored to the needs of pregnant and lactating populations. Enrolment of pregnant individuals is frequently hindered by concerns about maternal and fetal safety, negative media coverage, restrictive eligibility criteria, limited awareness, and socioeconomic barriers. Breastfeeding mothers and their infants face a convergence of social, cultural, physical and emotional challenges during a sensitive life stage. The unique needs of these populations must be carefully considered when designing research. Table 5.5 shows recruitment barriers and mitigation strategies to address them.  

Retention challenges that are specific to, or disproportionately affect, pregnant and lactating populations include: long study durations given high post-delivery mobility, long study visits, including travel time to the study site, given post-delivery changes in priority and risk perception – particularly after the birth of a healthy infant, and the absence of resting areas and private spaces for infant feeding. Addressing these issues requires a multifaceted approach that should include: engaging stakeholders early to identify and address unique challenges; designing pragmatic protocols; designing and utilizing targeted and effective communication strategies; optimizing study visits for participant convenience and benefit; training site staff; reassessing reimbursement frameworks, within existing context-specific ethical and regulatory guidance, to fairly compensate for time, inconvenience, and legitimate direct and indirect costs (including childcare, food, travel distance, accompaniment, and lost wages); and developing context-specific retention strategies to address identified challenges (e.g. use of mobile vans, leveraging AI technologies, etc.). By implementing tailored strategies and continuously evaluating their effectiveness, clinical trials may achieve better participant engagement and minimize delays, ultimately enhancing the research process. Moreover, these strategies may also enhance retention of non-pregnant and non-lactating populations. 

While it would be impossible to address every recruitment and retention challenge, Table 5.5 highlights some key overarching barriers to recruitment and retention and provides practical strategies that address these barriers. Supplementary resources include a comprehensive list of additional barriers and strategies reported in other research studies. 

Community engagement and involvement is key to ensuring that studies are designed to address the needs of an affected community, are designed with consideration to the unique needs of the pregnant women or breastfeeding mother–infant dyad and that all elements of the study have community input to maintain credibility and trust. The National Institute for Health and Care Research (United Kingdom of Great Britain and Northern Ireland) provides a useful set of guiding principles for community engagement and involvement:

FDA provides a guideline for pregnancy studies, in draft mode since 2018, but closed for comments.

Similarly a guideline for lactation studies is available, in draft form since 2005 and updated (but still in draft form) in 2019:

​​​​Additionally, the European Medicines Agency ICH E21 guideline on the inclusion of pregnant and breastfeeding individuals in clinical trials has been updated to include guidance on the inclusion of pregnant and lactating women in research, with an open consultation that closed in September 202​5

Additional guidance is expected.;

The Maternal and Infant Lactation pharmacoKinetic (MILK) and DolPHIN (Dolutegravir in HIV mothers and their neonates) study teams in Uganda and South Africa have successfully recruited and retained more than 400 mother–infant pairs in these studies over a one-year period. This commentary outlines community-engaged recruitment and retention strategies supported by robust maternal–infant safety monitoring.

Please see a document with a summary of barriers and solutions to recruitment and retention challenges specific to pregnant and lactating women.