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Influence of the full and new moon on onset of labor and spontaneous rupture of membranes
INFLUENCEOFTHEFULLANDNEWMOONONONSETOFLABOR ANDSPONTANEOUSRUPTUREQFMEMBRANES
Ellen W. Stern, MSN, CNM, Greer L. Glazer, PhD,RN, and Nick Sanduleak,
PhD
ABSTRACT This study investigates the influence of the new and full moon on onset of labor and spontaneous rupture of membranes. Admissions during the year 1984 to the labor and delivery unit of a large urban hospital in Cleveland, Ohio, in spontaneous labor or with rupture of the membranes, comprised the sample population (IV = 1999). Barometric pressure for each day of 1984 and the days of the full and new moon were also recorded. Frequencies for onset of labor and spontaneous rupture of membranes at the full and new moon were compared with days controlled for barometric pressure. Contingency analysis by chi-square was used. Results show a positive significant correlation of the onset of labor to the full moon when barometric pressure is not controlled. Frequencies of onset of labor and spontaneous rupture of membranes show positive nonsignificant correlation when barometric pressure is controlled. Results indicate a compounding, if not primary, influence by barometric pressure to that of the full and/or new moon.
The full moon has been the object of adoration, curiosity, and superstition for all of recorded history. Even in today’s pragmatic and scientifically advanced society, it is frequently blamed for a variety of happenstances. In this paper, the investigators will attempt to show a correlation between the moon and the onset of labor and spontaneous rupture of the membranes. The literature presents three possible explanations for a relationship between lunar phase and human behavioral and physiologic response. The biologic tide theoy1-4 proposes that the human body, comprised of 70% water, is influenced by the moon as are the ocean tides. As the gravitational pull increases at the time of the full moon, it theoretically to: Greer L. Kent State University, School of Nursing, Kent, OH 44242. Address
Glazer, PhD,
correspondence RN,
Journal of Nurse-Midwifery
could create a similar effect on the amniotic fluid. Some skeptics argue that the concentration of water in the human body is so miniscule in comparison to large bodies of water that the compounded effect observed in ocean tides would be reduced to insignificance in the human body. A second theory submits that barometric pressure changes can have a causal effect on human behavior and labor onset.1,5,6 This theory is based on the observation that the number of babies born during hurricanes and blizzards is increased.6 This is of significance since violent weather systems are associated with substantial drops in barometric pressure, a phenomenon which frequently occurs during full moons as well. Menaker and Menaker7 offer their explanation of increased birth rates at the time of the full moon by proposing that the effect of the moon
a Vol. 33, No. 2, March/April
Copyright 0 1988 by the American College of Nurse-Midwives
1988
comes at the time of conception and is due to its influence on cultural behaviors and also its possible effect on the menstrual cycle. With mean gestation defined as 266 days and a lunar cycle averaging 29.5 days, it is nine synodic lunar months from conception to birth. The synodic lunar month is a measurement of time from new moon to new moon.7 If conception is influenced by the full moon as hypothesized, then one can assume that birth would occur around the full moon nine months later. The Menakel8 study, the first major study to look at both the new and the full moon, showed the fewest number of births associated with the new moon and greatest number with the full moon. Today’s advanced astronomic data acknowledges that the new moon has gravitational effects on the earth equal to those of the full moon. More recent studies3s9-I1 improve
57 0091.2182/88/$03.50
upon earlier ones417 by including comparisons of birth rates and homicides to both the full and new moon. Studies that examine homicides and suicides in relation to full and new moons2Jo-12 differ in their findings as do studies looking at numbers of births. Thus, this study undertook to compare variations in birth rates for both the full moon and new moon. Schnurman4 conducted the first American study that attempted to look at the significance of the moon and its phases on numbers of births. Schnurman supported the findings of a 1938 German study conducted by Dr. W. Gunther, who was the first to acclaim a positive lunar effect on birth rate.3 Other obstetricians since Schnurman have investigated this relationship. In 1959, Menaker and Menaker substantiated Schnurman’s findings, concluding that a greater birth rate coincided with that phase of the moon centered at the full moon. Conclusions of other studies Ellen W. Stem received a Bachelor of Science in Nursing from Ohio State University in 1969, and a Master of Science in Nursing with a certificate in Midwiferyfrom Case Western Reserve Uniuersity in 1986. Ms. Stem is on the clinical faculty of the Frances Payne Bolton School of Nursing Department of Midwifery, and maintains a private midwijey practice, Woman’s Health Care Center, Inc., Garfield Heights, Ohio. Greer Glazer received a Bachelor of Science in Nursing from the Uniuersity of Michigan in 1976, and a Master of Science in MatemitylGynecologic Nursing from Case Western Reserve Uniuersity in 1979. Dr. Glazer received a Ph.D. in Nursing from Case Western Reserue Uniuersity in 1984, and is currently an Associate Professor of Parent/Child Nursing, Kent State Uniuersity, Kent, Ohio. Nick Sanduleak is a Senior Research Associate in the Astronomy Department at Case Western Reserue University, Cleueland, Ohio.
58
have also agreeds3J3 Other subsequent studies did not support a positive relationship between the full moon on birth rate.14-r7 There are several reasons for the variant findings in previous research. Although large sample sizes were used in each of the studies, ranging from 3,49gg to 50,000,7 they used variable time frames within the lunar cycles in which to compare birth rates. These ranged from the day of the full moon itselP5-l7 to three-day periods centering at the full and new moon;7,g to lunar quarters.3v4v8 Earlier studies did not take into consideration other variables; such as day of the week, time of the day, and season of the year, that are now known to have their own birth rate fluctuations.g Studies were not consistent in their use of cesarean deliveries and premature deliveries when determining numbers of births. Some would include them in their totals while others would not. Because a certain portion of these births began with natural onset of labor, they should be included in the number of births being used for the study. The most obvious error in all of the studies is their use of birth rates, rather than onset of labor, as the variable against which the phase of the moon must be correlated. If the moon has an effect on the birth rate, it could only do so by somehow influencing the time of the onset of labor with the resultant end in the birth itself. In previous studies, if labor onset occurred during the time frame being used, it would not be unlikely for a number of the subsequent births to occur outside the designated parameter and thus be omitted from the totals for that specified period of time. It is also feasible that the influence of the full moon on labor could come from its possible effect on spontaneous rupture of the membranes. When pregnancy is near term, rupture of the membranes is likely to lead to the onset of labor within 24 hours.18 While rup-
ture could occur during the designated time parameter, onset of labor and delivery could fall beyond and once again affect the outcome of the study. Thus, this investigation gauged the effect of the full moon not on number of births, but rather on the number of spontaneous labors established and the number of occurrences of spontaneous rupture of the membranes. In order to eliminate the strong environmental influence of barometric pressure on parturition or spontaneous rupture of membranes, it was controlled for as a variable. Weather patterns, such as hurricanes, typhoons, and heavy rainfall, are associated with low barometric pressure readings. The lunar influence over heavy rainfall was confirmed in a 50 year survey conducted by scientists from New York University and the U.S. Weather Bureau.’ Thus, it was significant to control for this possible effect when comparing time frames, This has not been done in any study to date, although Kaplanlg found no correlation between temperature and barometric pressure and the onset of parturition. The purpose of this study was to identify if there is a relationship between the full and new moon and the onset of labor and spontaneous rupture of the membranes in pregnant women. DEFINITION
OF TERMS
day 15 when half the moon receives reflected light from the sun. The time frame used includes the 24 hours before the day of the full moon and the 24 hours after. Nets moon-lunar day one when none of the moon receives any reflected light from the sun. The time frame used includes the 24 hours before the day of the new moon and the 24 hours after. Onset of laborwhen uterine contractions of sufficient frequency, intensity, and duration to bring about Full moon-lunar
Journal of Nurse-Midwifery
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33. No. 2, March/April 1988
readily demonstrable effacement and dilation of the cervix are attained18 resulting in the admission of the woman into the labor and delivery unit.
Spontaneous rupture of membranes -evidence of escape of amniotic fluid from the vagina without the use of artificial intervention and documented by gross visualization or a positive fern test. METHODS
Setting The setting was a large tertiary university hospital located in Cleveland, Ohio. In addition to being a tertiary level facility, MacDonald Hospital serves as a referral hospital for the high risk obstetric population from several counties in both the metropolitan area and beyond. Sample The sample consisted of all women, 20 or more weeks in gestation, who were admitted to the labor and delivery unit stating they were in labor or had rupture of membranes during 1984. Inductions performed for premature rupture of membranes were used in the data base as were any cesarean section deliveries that followed spontaneous onset of labor or premature rupture of membranes. There were 2268 charts requested. Of these, 59 charts were unavailable (2.6%) and 208 (9.2%) were not reviewed as they were deemed not applicable per the criteria required. This left the sample as 1999. Of the 1999 charts reviewed, 32 consisted of patients who were admitted on more than one separate occasion for premature labor. Thus, 1999 indicates admissions as opposed to actual patients. Demographic information is presented in Table 1. Procedure for Data Collection Data pertaining to this quantitative retrospective study were compiled
Journal of Nurse-Midwifery
??Vol.
from labor and delivery information routinely recorded. Lists of all patients admitted to the labor and delivery unit of MacDonald Hospital for the year 1984 were obtained from the hospital computer files. Charts for these admissions were then requested from the hospital record room. The forms on each woman meeting the inclusion criteria admitted to the labor and delivey unit of MacDonald Hospital for Women during the year specified were reviewed by the principal investigator and a trained research assistant. Readings of barometric pressure were obtained from the official recording station of the National Weather Service. Meterologic factors are recorded hourly and published records are available to the public upon request. Dates of both the full moon and new moon were obtained from records of N. Sanduleak, Associate Professor of astronomy at Case Western Reserve University. All data was collected for a full year, from January 1, 1984, 12:Ol a.m. to December 31, 1984, 11:50 p.m. A full year’s data collection was used to re-
TABLE
1
Demographic of sample
characteristics
Characteristic
n (% of total sample)
Age (in years): Range = 13-44 X = 26.24 SD = 6.46
Parity nullipara primipara multipara* grandmultiparat
Patient Classification private clinic Type of delivery vaginal cesarean undelivered N = 1999. * 2-4 t 5-9
pregnancies. pregnancies.
33, No. 2, March/April 1988
724 654 582 39
(31.9%) (28.8%) (25.6%) (1.7%)
881 (39.9%) 1118 (49.3%) 1424 (62.8%) 512 (22.6%) 62 (2.7%)
duce bias in the results due to monthly and seasonal variabilities. Instruments Two tools developed by the investigators were used. One tool listed date and time of admission, date and time of onset of labor, date and time of spontaneous rupture of membranes prior to admission, age, gravidity and parity, expected date of confinement, date and time of delivery, the type of delivery (vaginal or cesarean), and the use of induction. The second data collection tool listed all dates for the new and full moon for the same year as well as barometric pressure readings for each day of that year.
RESULTS
Data on the Full and New Moon and Barometric Pressure Information on the lunar phases of the full moon and new moon as well as that of barometric pressure were recorded. A three-day span incorporating the 24 hours both before and after each new and full moon in addition to the day of each was used in analyzing the data. For simplicity, each three-day span is referred to as the new moon or full moon. The full and new moons accounted for 75 days of the year of 1984. The days on which the new and full moon fell were slightly less evenly distributed than all the days during the year, but were found to be nonsignificant. Station pressure (barometric pressure corrected for feet above sea level for an area) for each day of the year 1984 was collected from the LCD (Local Climatological Data) log books of the National Weather Service at Cleveland Hopkins International Airport. Average station pressures were obtained as well as rises or falls of barometric pressure throughout each day. In comparison, 18.6% of the days of the new and full moon had barometric pressure
59
drops greater than 0.2 inches while 15.6% of all other days during the year had the equivalent drops in pressure. A fall of 0.2 inches in barometric pressure is considered a significant drop (J. May, personal communication, April 10, 1986), and is generally associated with the advent of inclement weather. Research Questions There was a significant positive correlation between the full moon and onset of labor when not controlled for barometric pressure (x2 = 5.018, df = 1, p = .025). The same did not hold true upon examination of the day of spontaneous rupture of membranes (SROM), when it occurred before the onset of labor. There were 64 occurrences of spontaneous rupture of membranes before the onset of labor on the days of the full moon, while there were 52 occurrences during the days of the new moon. A nonsignificant relationship was found (x2 = 1.241, df = 1, p = .265) between spontaneous rupture of the membranes and the new or full moon. There was a nonsignificant relationship for both the new moon and full moon to onset of labor (x2 = 0.968, dj = 1, p = .325) and spontaneous rupture of membranes (x2 = 0.004, dj = 1, p = .948) when barometric pressure was controlled. Additional Findings It was of interest to examine onset of
labor and spontaneous rupture of the membranes for gestations of 20 to 36 weeks to see if the moon phase has any correlation to premature labor or premature rupture of membranes. The days for the full and new moon were combined and matched to days controlled for barometric pressure and days of the week. There was a greater frequency of premature onset of labor during the new and full moon (69) as compared with other days of like barometric pressure (54) although no statistical 60
significance was found (x2 = 1.829, df = 1, p = .176). For SROM during the same gestations, the correlation was also nonsignificant (x2 = 3.028, df = 1, p = .079). DISCUSSION
The findings of this study, using onset of labor as a variable, support a significant positive correlation when a comparison of frequencies for the new moon and full moon are given with no control for barometric pressure. This correlation did not, however, hold true when spontaneous rupture of membranes was the variable identified. As gravitational pull on the earth is relatively equal during the new moon and the full moon, like frequencies should have been expected. However, as this was not the result, it becomes necessary to consider other factors which may influence the onset of parturition during the full moon. An examination of the Luni-Solar Tidal Index for the full and new moon shows equal numbers of high and medium values for each, lending no support to any combined gravitational effect by the sun and the moon as influencing the onset of labor. Barometric pressure has been suggested as another variable that may influence onset of labor,1g~20although a 1975 studyI showed no correlation. The average barometric pressure for the study area (station pressure) is 29.200 (J. May, personal communication, April 10, 1986). In determining days of low station pressure, those days with a reading less than 29.100 were considered, while days in which there was a significant barometric pressure drop (greater than 0.2 inches) during the day were thus indicated. Previous studies have implicated low barometric pressure1~20 or the significant falling of barometric pressure (J. May, personal communication, April 10, 1986) as having influence on the onset of labor, and possibly influencing the advent of spontaneous rupture of mem-
branes.*’ It is of particular interest to note that previous research has implicated days of inclement weather as associated with significant drops in barometric pressure. These weather patterns are more frequently seen at the time of the full moon.’ This fact is substantiated in this study with a 3% greater number of days during the full and new moon showing a significant drop in barometric pressure than other days during the year 1984. With falling barometric pressure possibly having influence over the onset of labor or spontaneous rupture of membranes, this study controlled for this variable as closely as possible, while still trying to control for the days of the week as well. The findings indicate that when barometric pressure is controlled for, there is no significant relationship between the onset of labor or spontaneous rupture of membranes during the new and full moon and those of other days. Neither could an influence be determined for premature labor (equal to or less than 36 weeks). Demonstration of a significant positive relationship between the full moon and the onset of labor when barometric pressure is not controlled for, yet finding no significance when it is controlled, seem to indicate that barometric pressure and the full moon, in combination, may influence the onset of labor. Possible explanations might be the moon’s influence over weather that is responsible for the positive correlation found. Or perhaps other factors related to the full moon that have not yet been identified are responsible. At the present, the findings of this study do not support a direct influence over the spontaneous rupture of membranes by the full and new moon. There are several limitations of the study. Manual recording by data collectors of such a large volume of data is tedious and promotes errors when done for long periods of time. If doing a retrospective study, it would
Journal of Nurse-Midwifery
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33, No. 2, March/April 1988
be best to use hospitals that have computerized their information to minimize recording errors. In addition, onset of labor is subjective information. It is obtained from the woman upon admission and is frequently altered by nursing personnel at their discretion as to when they think labor began. This was noted on many charts, as the time recorded on the admission workup by the physician as labor onset was frequently different from that recorded by the nurse. Although this study supports a positive correlation for the effect of the full moon on the onset of labor, indications are that it is possibly due to the significantly higher number of those days which demonstrate a major drop in barometric pressure. The conflicting results when barometric pressure is controlled makes it difficult to apply the findings until further research is done. Studies that cover more than a one year period and more than one geographic area would help provide more conclusive information on this subject. Analysis should include matching of those days of the full moon and new moon independently of each other. They should then be tested against days of like barometric pressure as well as higher barometric pressures in order to better identify the influence of barometric pressure as a variable. Analysis of the data would prove interesting on a monthby-month basis in order to better visualize any variations. A prospective study rather than a retrospective study might provide better data, as the number of screening visits could be incorporated as well, and might be found to increase the activity on the labor unit without appearing in
Journal
of Nurse-Midwifery
??Vol.
the hospital records. In addition, comparison of deliveries versus onset of labor by statistical analysis would provide additional information.
8. Menaker W: Lunar periodicity with reference to live births. Am J Obstet Gynecol98:10021004, 1967.
The authors wish to acknowledge Lee-Wah Jane for invaluable assistance on development of the computer program for the analysis of the data. Thanks are also extended to Mr. J. May, meteorologist in charge at the National Oceanic and Atmospheric Administration station at Cleveland Hopkins International Airport in Cleveland, Ohio for his contribution of knowledge in the area of meteorology. In addition, thanks are extended to the Frances Payne Bolton School of Nursing Alumni Association for their financial support of this project.
10. Pokorny S: Moon phases, suicide, and homicide. Am J Psychiatry, 121:6667, 1964.
REFERENCES
Katzeff P: Full Moons. New Jersey, Citadel Press, 1981. 2. Lieber A, Sherin, C: Homicides and the lunar cycle: toward a theory of lunar influence on human emotional dis1.
turbance. Am J Psychiatry, 129(1):6973, 1972. 3. McDonald R: Lunar and seasonal variations in obstetric factors. J Genet Psychol, 108:81-87, 1966. 4. Schnurman A: The effect of the moon on childbirth. Virginia Medical Monthly, 76: 78, 1948. 5. Geller S, Shannon H: The moon, weather, and mental hospital contacts: confirmation and explanation of the Transylvania effect. Journal of Psychiatric Nursing and Mental Health Sciences, 14: 13- 17, 1976. 6. Petersen W: The patient and the weather, in Katzeff P, Full moons. New Jersey: Citadel Press, 1981. 7. Menaker W, Menaker A: Lunar periodicity in human reproduction: a likely unit of biological time. Am J Obstet Gynecol 77:905-913, 1959.
33, No. 2, March/April 1988
9. Nalepka C, Jones S, Jones P: Time variations, births, and lunar association. Issues in Comprehensive Nursing, 6(2):81-89, 1983.
11. Sanduleak N: The moon is acquitted of murder in Cleveland. Skeptical Inquirer, spring:236-242m, 1985. 12. Pokorny S, Jachimczyk J: The questionable relationship between homicides and the lunar cycle. Am J Psychiatry, 131(7):827-828, 1974. 13. Criss T, Marcum J: A lunar effect on fertility. Sot Biol 28:75-80, 1981. 14. Abell G, Grenspan B: Human births and the phase of the moon. N Engl J Med 300:96, 1979. 15. Osley M, Summervilie D, Borst L: Natal@ and the moon. Am J Obstet Gynecol 117:413-417, 1973. 16. Rippman E: The moon and the birth rate. Am J Obstet Gynecol 117:413-417, 1957. 17. Schwab B: Delivery of babies and the full moon. Can Med Assoc J 113(6):489-493, 1975. 18. Pritchard J, MacDonald P, Gant N: Williams Obstetrics (17th ed.). Norwalk, CT: Appleton-Century-Crofts. 1985. 19. Kaplan M: A comparison between two meteorologic factors and the onset of parturition. Unpublished Master’s Thesis, University of Illinois at the Medical Center, Chicago, 1981. 20. Driscoll D, Merker D: A search for associations between weather and the onset of human parturition. Int J Biometeorol28:21 l-224, 1984. 21. Steinman G, Kleiner G: Spontaneous, premature rupture of membranes: Correlation with ambient atmospheric pressure. NY State J Med 78(6):900-901, 1978.
61
Ellen W. Stern, MSN, CNM, Greer L. Glazer, PhD,RN, and Nick Sanduleak,
PhD
ABSTRACT This study investigates the influence of the new and full moon on onset of labor and spontaneous rupture of membranes. Admissions during the year 1984 to the labor and delivery unit of a large urban hospital in Cleveland, Ohio, in spontaneous labor or with rupture of the membranes, comprised the sample population (IV = 1999). Barometric pressure for each day of 1984 and the days of the full and new moon were also recorded. Frequencies for onset of labor and spontaneous rupture of membranes at the full and new moon were compared with days controlled for barometric pressure. Contingency analysis by chi-square was used. Results show a positive significant correlation of the onset of labor to the full moon when barometric pressure is not controlled. Frequencies of onset of labor and spontaneous rupture of membranes show positive nonsignificant correlation when barometric pressure is controlled. Results indicate a compounding, if not primary, influence by barometric pressure to that of the full and/or new moon.
The full moon has been the object of adoration, curiosity, and superstition for all of recorded history. Even in today’s pragmatic and scientifically advanced society, it is frequently blamed for a variety of happenstances. In this paper, the investigators will attempt to show a correlation between the moon and the onset of labor and spontaneous rupture of the membranes. The literature presents three possible explanations for a relationship between lunar phase and human behavioral and physiologic response. The biologic tide theoy1-4 proposes that the human body, comprised of 70% water, is influenced by the moon as are the ocean tides. As the gravitational pull increases at the time of the full moon, it theoretically to: Greer L. Kent State University, School of Nursing, Kent, OH 44242. Address
Glazer, PhD,
correspondence RN,
Journal of Nurse-Midwifery
could create a similar effect on the amniotic fluid. Some skeptics argue that the concentration of water in the human body is so miniscule in comparison to large bodies of water that the compounded effect observed in ocean tides would be reduced to insignificance in the human body. A second theory submits that barometric pressure changes can have a causal effect on human behavior and labor onset.1,5,6 This theory is based on the observation that the number of babies born during hurricanes and blizzards is increased.6 This is of significance since violent weather systems are associated with substantial drops in barometric pressure, a phenomenon which frequently occurs during full moons as well. Menaker and Menaker7 offer their explanation of increased birth rates at the time of the full moon by proposing that the effect of the moon
a Vol. 33, No. 2, March/April
Copyright 0 1988 by the American College of Nurse-Midwives
1988
comes at the time of conception and is due to its influence on cultural behaviors and also its possible effect on the menstrual cycle. With mean gestation defined as 266 days and a lunar cycle averaging 29.5 days, it is nine synodic lunar months from conception to birth. The synodic lunar month is a measurement of time from new moon to new moon.7 If conception is influenced by the full moon as hypothesized, then one can assume that birth would occur around the full moon nine months later. The Menakel8 study, the first major study to look at both the new and the full moon, showed the fewest number of births associated with the new moon and greatest number with the full moon. Today’s advanced astronomic data acknowledges that the new moon has gravitational effects on the earth equal to those of the full moon. More recent studies3s9-I1 improve
57 0091.2182/88/$03.50
upon earlier ones417 by including comparisons of birth rates and homicides to both the full and new moon. Studies that examine homicides and suicides in relation to full and new moons2Jo-12 differ in their findings as do studies looking at numbers of births. Thus, this study undertook to compare variations in birth rates for both the full moon and new moon. Schnurman4 conducted the first American study that attempted to look at the significance of the moon and its phases on numbers of births. Schnurman supported the findings of a 1938 German study conducted by Dr. W. Gunther, who was the first to acclaim a positive lunar effect on birth rate.3 Other obstetricians since Schnurman have investigated this relationship. In 1959, Menaker and Menaker substantiated Schnurman’s findings, concluding that a greater birth rate coincided with that phase of the moon centered at the full moon. Conclusions of other studies Ellen W. Stem received a Bachelor of Science in Nursing from Ohio State University in 1969, and a Master of Science in Nursing with a certificate in Midwiferyfrom Case Western Reserve Uniuersity in 1986. Ms. Stem is on the clinical faculty of the Frances Payne Bolton School of Nursing Department of Midwifery, and maintains a private midwijey practice, Woman’s Health Care Center, Inc., Garfield Heights, Ohio. Greer Glazer received a Bachelor of Science in Nursing from the Uniuersity of Michigan in 1976, and a Master of Science in MatemitylGynecologic Nursing from Case Western Reserve Uniuersity in 1979. Dr. Glazer received a Ph.D. in Nursing from Case Western Reserue Uniuersity in 1984, and is currently an Associate Professor of Parent/Child Nursing, Kent State Uniuersity, Kent, Ohio. Nick Sanduleak is a Senior Research Associate in the Astronomy Department at Case Western Reserue University, Cleueland, Ohio.
58
have also agreeds3J3 Other subsequent studies did not support a positive relationship between the full moon on birth rate.14-r7 There are several reasons for the variant findings in previous research. Although large sample sizes were used in each of the studies, ranging from 3,49gg to 50,000,7 they used variable time frames within the lunar cycles in which to compare birth rates. These ranged from the day of the full moon itselP5-l7 to three-day periods centering at the full and new moon;7,g to lunar quarters.3v4v8 Earlier studies did not take into consideration other variables; such as day of the week, time of the day, and season of the year, that are now known to have their own birth rate fluctuations.g Studies were not consistent in their use of cesarean deliveries and premature deliveries when determining numbers of births. Some would include them in their totals while others would not. Because a certain portion of these births began with natural onset of labor, they should be included in the number of births being used for the study. The most obvious error in all of the studies is their use of birth rates, rather than onset of labor, as the variable against which the phase of the moon must be correlated. If the moon has an effect on the birth rate, it could only do so by somehow influencing the time of the onset of labor with the resultant end in the birth itself. In previous studies, if labor onset occurred during the time frame being used, it would not be unlikely for a number of the subsequent births to occur outside the designated parameter and thus be omitted from the totals for that specified period of time. It is also feasible that the influence of the full moon on labor could come from its possible effect on spontaneous rupture of the membranes. When pregnancy is near term, rupture of the membranes is likely to lead to the onset of labor within 24 hours.18 While rup-
ture could occur during the designated time parameter, onset of labor and delivery could fall beyond and once again affect the outcome of the study. Thus, this investigation gauged the effect of the full moon not on number of births, but rather on the number of spontaneous labors established and the number of occurrences of spontaneous rupture of the membranes. In order to eliminate the strong environmental influence of barometric pressure on parturition or spontaneous rupture of membranes, it was controlled for as a variable. Weather patterns, such as hurricanes, typhoons, and heavy rainfall, are associated with low barometric pressure readings. The lunar influence over heavy rainfall was confirmed in a 50 year survey conducted by scientists from New York University and the U.S. Weather Bureau.’ Thus, it was significant to control for this possible effect when comparing time frames, This has not been done in any study to date, although Kaplanlg found no correlation between temperature and barometric pressure and the onset of parturition. The purpose of this study was to identify if there is a relationship between the full and new moon and the onset of labor and spontaneous rupture of the membranes in pregnant women. DEFINITION
OF TERMS
day 15 when half the moon receives reflected light from the sun. The time frame used includes the 24 hours before the day of the full moon and the 24 hours after. Nets moon-lunar day one when none of the moon receives any reflected light from the sun. The time frame used includes the 24 hours before the day of the new moon and the 24 hours after. Onset of laborwhen uterine contractions of sufficient frequency, intensity, and duration to bring about Full moon-lunar
Journal of Nurse-Midwifery
??Vol.
33. No. 2, March/April 1988
readily demonstrable effacement and dilation of the cervix are attained18 resulting in the admission of the woman into the labor and delivery unit.
Spontaneous rupture of membranes -evidence of escape of amniotic fluid from the vagina without the use of artificial intervention and documented by gross visualization or a positive fern test. METHODS
Setting The setting was a large tertiary university hospital located in Cleveland, Ohio. In addition to being a tertiary level facility, MacDonald Hospital serves as a referral hospital for the high risk obstetric population from several counties in both the metropolitan area and beyond. Sample The sample consisted of all women, 20 or more weeks in gestation, who were admitted to the labor and delivery unit stating they were in labor or had rupture of membranes during 1984. Inductions performed for premature rupture of membranes were used in the data base as were any cesarean section deliveries that followed spontaneous onset of labor or premature rupture of membranes. There were 2268 charts requested. Of these, 59 charts were unavailable (2.6%) and 208 (9.2%) were not reviewed as they were deemed not applicable per the criteria required. This left the sample as 1999. Of the 1999 charts reviewed, 32 consisted of patients who were admitted on more than one separate occasion for premature labor. Thus, 1999 indicates admissions as opposed to actual patients. Demographic information is presented in Table 1. Procedure for Data Collection Data pertaining to this quantitative retrospective study were compiled
Journal of Nurse-Midwifery
??Vol.
from labor and delivery information routinely recorded. Lists of all patients admitted to the labor and delivery unit of MacDonald Hospital for the year 1984 were obtained from the hospital computer files. Charts for these admissions were then requested from the hospital record room. The forms on each woman meeting the inclusion criteria admitted to the labor and delivey unit of MacDonald Hospital for Women during the year specified were reviewed by the principal investigator and a trained research assistant. Readings of barometric pressure were obtained from the official recording station of the National Weather Service. Meterologic factors are recorded hourly and published records are available to the public upon request. Dates of both the full moon and new moon were obtained from records of N. Sanduleak, Associate Professor of astronomy at Case Western Reserve University. All data was collected for a full year, from January 1, 1984, 12:Ol a.m. to December 31, 1984, 11:50 p.m. A full year’s data collection was used to re-
TABLE
1
Demographic of sample
characteristics
Characteristic
n (% of total sample)
Age (in years): Range = 13-44 X = 26.24 SD = 6.46
Parity nullipara primipara multipara* grandmultiparat
Patient Classification private clinic Type of delivery vaginal cesarean undelivered N = 1999. * 2-4 t 5-9
pregnancies. pregnancies.
33, No. 2, March/April 1988
724 654 582 39
(31.9%) (28.8%) (25.6%) (1.7%)
881 (39.9%) 1118 (49.3%) 1424 (62.8%) 512 (22.6%) 62 (2.7%)
duce bias in the results due to monthly and seasonal variabilities. Instruments Two tools developed by the investigators were used. One tool listed date and time of admission, date and time of onset of labor, date and time of spontaneous rupture of membranes prior to admission, age, gravidity and parity, expected date of confinement, date and time of delivery, the type of delivery (vaginal or cesarean), and the use of induction. The second data collection tool listed all dates for the new and full moon for the same year as well as barometric pressure readings for each day of that year.
RESULTS
Data on the Full and New Moon and Barometric Pressure Information on the lunar phases of the full moon and new moon as well as that of barometric pressure were recorded. A three-day span incorporating the 24 hours both before and after each new and full moon in addition to the day of each was used in analyzing the data. For simplicity, each three-day span is referred to as the new moon or full moon. The full and new moons accounted for 75 days of the year of 1984. The days on which the new and full moon fell were slightly less evenly distributed than all the days during the year, but were found to be nonsignificant. Station pressure (barometric pressure corrected for feet above sea level for an area) for each day of the year 1984 was collected from the LCD (Local Climatological Data) log books of the National Weather Service at Cleveland Hopkins International Airport. Average station pressures were obtained as well as rises or falls of barometric pressure throughout each day. In comparison, 18.6% of the days of the new and full moon had barometric pressure
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drops greater than 0.2 inches while 15.6% of all other days during the year had the equivalent drops in pressure. A fall of 0.2 inches in barometric pressure is considered a significant drop (J. May, personal communication, April 10, 1986), and is generally associated with the advent of inclement weather. Research Questions There was a significant positive correlation between the full moon and onset of labor when not controlled for barometric pressure (x2 = 5.018, df = 1, p = .025). The same did not hold true upon examination of the day of spontaneous rupture of membranes (SROM), when it occurred before the onset of labor. There were 64 occurrences of spontaneous rupture of membranes before the onset of labor on the days of the full moon, while there were 52 occurrences during the days of the new moon. A nonsignificant relationship was found (x2 = 1.241, df = 1, p = .265) between spontaneous rupture of the membranes and the new or full moon. There was a nonsignificant relationship for both the new moon and full moon to onset of labor (x2 = 0.968, dj = 1, p = .325) and spontaneous rupture of membranes (x2 = 0.004, dj = 1, p = .948) when barometric pressure was controlled. Additional Findings It was of interest to examine onset of
labor and spontaneous rupture of the membranes for gestations of 20 to 36 weeks to see if the moon phase has any correlation to premature labor or premature rupture of membranes. The days for the full and new moon were combined and matched to days controlled for barometric pressure and days of the week. There was a greater frequency of premature onset of labor during the new and full moon (69) as compared with other days of like barometric pressure (54) although no statistical 60
significance was found (x2 = 1.829, df = 1, p = .176). For SROM during the same gestations, the correlation was also nonsignificant (x2 = 3.028, df = 1, p = .079). DISCUSSION
The findings of this study, using onset of labor as a variable, support a significant positive correlation when a comparison of frequencies for the new moon and full moon are given with no control for barometric pressure. This correlation did not, however, hold true when spontaneous rupture of membranes was the variable identified. As gravitational pull on the earth is relatively equal during the new moon and the full moon, like frequencies should have been expected. However, as this was not the result, it becomes necessary to consider other factors which may influence the onset of parturition during the full moon. An examination of the Luni-Solar Tidal Index for the full and new moon shows equal numbers of high and medium values for each, lending no support to any combined gravitational effect by the sun and the moon as influencing the onset of labor. Barometric pressure has been suggested as another variable that may influence onset of labor,1g~20although a 1975 studyI showed no correlation. The average barometric pressure for the study area (station pressure) is 29.200 (J. May, personal communication, April 10, 1986). In determining days of low station pressure, those days with a reading less than 29.100 were considered, while days in which there was a significant barometric pressure drop (greater than 0.2 inches) during the day were thus indicated. Previous studies have implicated low barometric pressure1~20 or the significant falling of barometric pressure (J. May, personal communication, April 10, 1986) as having influence on the onset of labor, and possibly influencing the advent of spontaneous rupture of mem-
branes.*’ It is of particular interest to note that previous research has implicated days of inclement weather as associated with significant drops in barometric pressure. These weather patterns are more frequently seen at the time of the full moon.’ This fact is substantiated in this study with a 3% greater number of days during the full and new moon showing a significant drop in barometric pressure than other days during the year 1984. With falling barometric pressure possibly having influence over the onset of labor or spontaneous rupture of membranes, this study controlled for this variable as closely as possible, while still trying to control for the days of the week as well. The findings indicate that when barometric pressure is controlled for, there is no significant relationship between the onset of labor or spontaneous rupture of membranes during the new and full moon and those of other days. Neither could an influence be determined for premature labor (equal to or less than 36 weeks). Demonstration of a significant positive relationship between the full moon and the onset of labor when barometric pressure is not controlled for, yet finding no significance when it is controlled, seem to indicate that barometric pressure and the full moon, in combination, may influence the onset of labor. Possible explanations might be the moon’s influence over weather that is responsible for the positive correlation found. Or perhaps other factors related to the full moon that have not yet been identified are responsible. At the present, the findings of this study do not support a direct influence over the spontaneous rupture of membranes by the full and new moon. There are several limitations of the study. Manual recording by data collectors of such a large volume of data is tedious and promotes errors when done for long periods of time. If doing a retrospective study, it would
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be best to use hospitals that have computerized their information to minimize recording errors. In addition, onset of labor is subjective information. It is obtained from the woman upon admission and is frequently altered by nursing personnel at their discretion as to when they think labor began. This was noted on many charts, as the time recorded on the admission workup by the physician as labor onset was frequently different from that recorded by the nurse. Although this study supports a positive correlation for the effect of the full moon on the onset of labor, indications are that it is possibly due to the significantly higher number of those days which demonstrate a major drop in barometric pressure. The conflicting results when barometric pressure is controlled makes it difficult to apply the findings until further research is done. Studies that cover more than a one year period and more than one geographic area would help provide more conclusive information on this subject. Analysis should include matching of those days of the full moon and new moon independently of each other. They should then be tested against days of like barometric pressure as well as higher barometric pressures in order to better identify the influence of barometric pressure as a variable. Analysis of the data would prove interesting on a monthby-month basis in order to better visualize any variations. A prospective study rather than a retrospective study might provide better data, as the number of screening visits could be incorporated as well, and might be found to increase the activity on the labor unit without appearing in
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the hospital records. In addition, comparison of deliveries versus onset of labor by statistical analysis would provide additional information.
8. Menaker W: Lunar periodicity with reference to live births. Am J Obstet Gynecol98:10021004, 1967.
The authors wish to acknowledge Lee-Wah Jane for invaluable assistance on development of the computer program for the analysis of the data. Thanks are also extended to Mr. J. May, meteorologist in charge at the National Oceanic and Atmospheric Administration station at Cleveland Hopkins International Airport in Cleveland, Ohio for his contribution of knowledge in the area of meteorology. In addition, thanks are extended to the Frances Payne Bolton School of Nursing Alumni Association for their financial support of this project.
10. Pokorny S: Moon phases, suicide, and homicide. Am J Psychiatry, 121:6667, 1964.
REFERENCES
Katzeff P: Full Moons. New Jersey, Citadel Press, 1981. 2. Lieber A, Sherin, C: Homicides and the lunar cycle: toward a theory of lunar influence on human emotional dis1.
turbance. Am J Psychiatry, 129(1):6973, 1972. 3. McDonald R: Lunar and seasonal variations in obstetric factors. J Genet Psychol, 108:81-87, 1966. 4. Schnurman A: The effect of the moon on childbirth. Virginia Medical Monthly, 76: 78, 1948. 5. Geller S, Shannon H: The moon, weather, and mental hospital contacts: confirmation and explanation of the Transylvania effect. Journal of Psychiatric Nursing and Mental Health Sciences, 14: 13- 17, 1976. 6. Petersen W: The patient and the weather, in Katzeff P, Full moons. New Jersey: Citadel Press, 1981. 7. Menaker W, Menaker A: Lunar periodicity in human reproduction: a likely unit of biological time. Am J Obstet Gynecol 77:905-913, 1959.
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9. Nalepka C, Jones S, Jones P: Time variations, births, and lunar association. Issues in Comprehensive Nursing, 6(2):81-89, 1983.
11. Sanduleak N: The moon is acquitted of murder in Cleveland. Skeptical Inquirer, spring:236-242m, 1985. 12. Pokorny S, Jachimczyk J: The questionable relationship between homicides and the lunar cycle. Am J Psychiatry, 131(7):827-828, 1974. 13. Criss T, Marcum J: A lunar effect on fertility. Sot Biol 28:75-80, 1981. 14. Abell G, Grenspan B: Human births and the phase of the moon. N Engl J Med 300:96, 1979. 15. Osley M, Summervilie D, Borst L: Natal@ and the moon. Am J Obstet Gynecol 117:413-417, 1973. 16. Rippman E: The moon and the birth rate. Am J Obstet Gynecol 117:413-417, 1957. 17. Schwab B: Delivery of babies and the full moon. Can Med Assoc J 113(6):489-493, 1975. 18. Pritchard J, MacDonald P, Gant N: Williams Obstetrics (17th ed.). Norwalk, CT: Appleton-Century-Crofts. 1985. 19. Kaplan M: A comparison between two meteorologic factors and the onset of parturition. Unpublished Master’s Thesis, University of Illinois at the Medical Center, Chicago, 1981. 20. Driscoll D, Merker D: A search for associations between weather and the onset of human parturition. Int J Biometeorol28:21 l-224, 1984. 21. Steinman G, Kleiner G: Spontaneous, premature rupture of membranes: Correlation with ambient atmospheric pressure. NY State J Med 78(6):900-901, 1978.
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