Is there a relationship between moon phase and birthrate? Finkenthal, N., and Woo, S. Desert View High School, Tucson, Arizona INTRODUCTION: The moon has been linked to disasters, accidents, mental illness, crime suicide, birthrates, fertility and werewolves, among other things. The powerful allure of the moon is full of beauty, legend, myth and romance. The moon passes through four major shapes during a cycle that repeats itself every 29.5 days. The revolution of the moon around the Earth makes the moon appear as if it is changing shape in the sky, and this is caused by the different angles from which we see the bright part of the Moon's surface. These are called "phases" of the moon, whereby the moon just reflects the light of the Sun according to these phases. The phases always follow one another in the same order, and are caused by the relative positions of the earth, sun, and moon. Our interest in the moon or the phases of the moon revolved around the possibility that there may be more births during a full moon. Many studies have been conducted which try to correlate birthrates to the phases of the moon with contradictory results but with a few significant findings. 1-7 The purpose of the study was to make comparisons and identify any possible relationships of births in Arizona relative to moon phase. METHODS: The research design is descriptive using retrospective data. Actual data was collected from the Arizona Department of Health Services, Division of Public Health Services, Health Status and Vital Statistics website for all births and cesarean deliveries for the years 2000 to 2002 in Arizona, and from the U.S. Naval Observatory website, Astronomical Applications Department for four major phases of the moon, the full moon, the last quarter, the new moon, and the first quarter for the years 2000, 2001 and Medline database was searched for previous studies related to moon phases and birthrates. Inclusion criteria included daily birthrates minus scheduled and or second cesarean deliveries in the state of Arizona. After data was collected, comparisons were made to verify if any relationship between number of births and moon phase exists. The data analysis was done using descriptive statistics in Microsoft Excel to determine if the relationship was statistically significant. DATA SUMMARY: Results are illustrated in the figures and tables. Confidence Intervals for differences in the means of daily, monthly, and yearly numbers of births were analyzed for each moon phase. The tables illustrated show the descriptive statistical data that compared birthrate to moon phase for years 2000, 2001, and The computed intervals with a given probability of 95% showed that the means of total number of births for all years analyzed is contained within this interval. DISCUSSION: Our findings disproved the hypothesis that the number of births had a relationship with any moon phase. Although a few studies have shown slightly weak relationships, most of the published research studies obtained contradictory results. 1-7 Future directions for research may include measuring hormonal or neurochemical changes during moon phases, which maybe a better indicator of a relationship. Hormones and neurochemicals play important roles in body regulatory functions, and may indicate elevated levels of particular hormones during the different moon phases. SOURCE: Arizona Department of Health Services, Div. of Health Services, Arizona Vital Statistics website: And U.S. Naval Observatory website: Source: Source: Arizona Department of Health Services, Div. of Health Services, Arizona Vital Statistics Website: And U.S. Naval Observatory website: CONCLUSION: The confidence intervals computed from the data analyses do not indicate a relationship between the number of births and moon phase. The confidence interval for the data set must be 5% or lower in order to be declared statistically significant. Therefore, the confidence intervals of all the moon phases, which are greater than 5%, show that the relationship between moon phase and birthrate is not statistically significant. Table 1. New Moon Mean Standard Error Median231.5 Mode234 Standard Deviation Sample Variance Kurtosis Skewness Range150 Minimum138 Maximum288 Sum7917 Count36 Largest(1)288 Smallest(1)138 Confidence Level(95.0%) Table 2. First Quarter Mean Standard Error Median224 Mode218 Standard Deviation Sample Variance Kurtosis Skewness Range199 Minimum163 Maximum362 Sum8146 Count36 Largest(1)362 Smallest(1)163 Confidence Level(95.0%) Table 3. Full Moon Mean Standard Error Median224 Mode205 Standard Deviation Sample Variance Kurtosis Skewness Range308 Minimum135 Maximum443 Sum8128 Count36 Largest(1)443 Smallest(1)135 Confidence Level(95.0%) Table 4. Last Quarter Mean Standard Error Median228 Mode244 Standard Deviation Sample Variance Kurtosis Skewness Range297 Minimum151 Maximum448 Sum8086 Count36 Largest(1)448 Smallest(1)151 Confidence Level(95.0%) Source: Arizona Department of Health Services, Div. of Health Services, Arizona Vital Statistics website: And U.S. Naval Observatory website: Figure 1. Moon Phases Orbiting Earth