From anecdotal evidence of prescription prevalence to register-based facts -- a feasibility report for human clinical lactation studies on medication in association with breastfeeding.

Background: With as few as 5% of available medications being adequately monitored, tested and labelled with safety information for use in breastfeeding women, there is a great need to monitor and evaluate the potential risk of transfer of medicines to the infant. The lack of conclusive evidence regarding the transfer of a drug to breastfeeding infants could result in increased risks for both mothers and their children. Anecdotal reports from clinicians in Sweden suggest that clinical practices vary, with some physicians discontinuing the medication while others continue its use during breastfeeding. Method: ology In order to obtain reliable data on prescriptions, and to identify clinical centers for a clinical trial, we requested the National Board of Health and Welfare to conduct a cross-match between the National Prescribed Drug Register (NPDR) and the National Medical Birth Register (NMBR). By obtaining real world data on prescription prevalence we were able to select clinical centers across Sweden for setting up mother-infant pair protocols. Conclusion: Feasibility of clinical lactation studies may be attained through the use of national registers with data enabling direct information and recruitment of participants as well as identification of appropriate clinical centers to do the sampling.