1 2 3 4 5 6 While there is a burgeoning knowledge base on how to improve pregnancy outcomes, there are few studies examining the effects of this knowledge base on actual practice patterns. It is not well known to what extent health care providers are translating preconception care knowledge into practice for all women capable of becoming pregnant (whether planning pregnancy or not). Material and methods A literature review between 1966 and September 2005 was performed using Medline to examine the impact of preconception care trials and recommendations on the clinical practice patterns of health care providers. Key words included preconception care, preconception counseling, preconception surveys, practice patterns, pregnancy outcomes, prepregnancy planning, and prepregnancy surveys. Relevant review articles regarding preconception care were also included. All studies had to be done in the United States. Studies that examined existing clinical practices and approaches directly to providing preconception care were eligible for inclusion. Studies that used indirect methods of measurement, e.g., interviews with women as a means of assessing preconception care practices of providers, were not included. A total of 11 studies were located and included analyses of practice patterns of various health care providers and specialties (see Appendix). Results 7 8 9 9 10 11 12 13 14 14 15 16 Discussion 17 18 19 20 21 22 23 24 25 26 29 30 26 27 31 Studies evaluating effective preconception care interventions and strategies are numerous, and continue to grow. There is also an increasing amount of information about how patients assimilate and act upon recommendations regarding preconception care. There is little data, however, that analyzes the impact and integration of preconception care innovations on daily clinical practice(s). One limitation of this literature review is that articles with secondary goals of evaluating actual clinical practices may have been overlooked. Efforts were made to include all relevant search terms but it is possible that articles written before 1985 may have been inadvertently excluded if different keywords were used at that time. Nonetheless, there is a large need for further research into the contrast between the science of preconception care and the reality of actual clinical practice. Conclusion 23 32 34 In 2005, the Centers for Disease Control and Prevention sponsored a national summit regarding preconception care with a broad cross-section of stakeholders. Efforts are currently underway to develop a uniform set of national recommendations and guidelines for preconception care. Understanding how preconception care is presently incorporated and manifested in current medical practices should help in the development of these national guidelines. Knowing where, how, and why some specific preconception recommendations have been successfully adopted and translated into clinical practice, as well as barriers to implementation of other recommendations or guidelines, is vitally important in developing an overarching set of national guidelines. Ultimately, the success of these recommendations rests on their ability to influence and shape women's health policy.