The "Christmas Effect" and other biometeorologic influences on childbearing and the health of women

Objective: To review the body of literature addressing biometeorologic and chronobiologic effects on conception, pregnancy, parturition, and other health conditions. Data Sources: Computerized searches of MEDLINE, PUBMED, CINAHL, and the World Wide Web. Study Selection: Studies, including international research, dating from 1938 to 2001. Data Extraction: Data were extracted and informotion organized under the following categories: influence of leisure time and seasonality on the rate of conception and birth, the relationship of meteorologic changes and lunar cycles to childbearing, the "Christmas Effect" and its impact on other health outcomes, and nursing implications. Data Synthesis: Research from the disciplines of biometeorology and ckronobiology indicates that there are patterns in the occurrence of conception, pregnancy, and onset of labor that vary in timing and amplitude in different populations and geographic regions. Consideration of these factors should be included in the analysis of birth data when planning and providing maternity care. The Christmas Effect is one of the most predominant seasonal patterns that can be seen in birth data throughout the world. Conclusions: Biometeorologic and other cyclic phenomena are underused in the United States in planning and providing maternity care. These phenomena warrant consideration when planning holistic health care.