Does lunar position influence the time of delivery? A statistical analysis

doi:10.1016/S0301-2115(97)00226-1

European Journal of Obstetrics & Gynecology and Reproductive Biology

Volume 77, Issue 1, 1 March 1998, Pages 47-50

https://doi.org/10.1016/S0301-2115(97)00226-1 Get rights and content

Abstract

Objective: To study the relationship between lunar position and the day of delivery; to investigate the synodic distribution of spontaneous deliveries, especially in relation to the presence of a full moon. Study Design: Retrospective analysis of 1248 spontaneous full-term deliveries in three-year period (36 lunar months), setted at Department of Obstetrics and Gynaecology, Civil Hospital, Fano (Marche, Italy), using circular statistics techniques. Results: A connection between the distribution of spontaneous full-term deliveries and the lunar month was found. The effect of the phases of the moon seems to be particularly relevant in multiparae and plurigravidae; in these cases, the mean day of delivery corresponds to the first or second day after the full moon. Conclusions: In this paper the effect of lunar phases on the time of delivery is shown. This influence seems to be especially relevant in the case of multiparae and plurigravidae. Nevertheless, it is too weak to allow for prediction regarding the days with the highest frequency of deliveries.

Introduction

Many authors 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, both in the past and more recently, attempted to study the possible influence of lunar phases on the time of delivery. Nevertheless, they did not always use suitable statistical methods for this kind of problem; for example, the subdivision of deliveries is sometimes approximate, because they are grouped into four classes which correspond to the periods between new moon, first quarter, full moon and last quarter. In this sense, the necessity of a more accurate study was pointed out by some authors [2].

In order to avoid the approximations associated with the arbitrariness of the definition of the classes and the remainders of the splitting of lunar month (in fact its duration is not exactly divisible by 24 hours), we did not group deliveries into classes, but we treated them separately, and we associated each one with a single measure.

In this paper we studied the influence of the lunar position on the time of delivery (especially regarding the day of a full moon), through the analysis of the distribution of spontaneous full-term delivery within the span of the lunar month. Moreover, since some authors took account of parity and/or maternal age (that are highly correlated) both in lunar cycle effects 2, 9and in other rhythmicities [14], we also performed a comparison between nulliparae and multiparae and between primigravidae and plurigravidae.

Section snippets

Methods

We considered all spontaneous full-term (38–42 weeks of pregnancy) deliveries which occurred at the Civil Hospital in Fano (Marche, Italy) in the three-year period 1993–1995. Data were drawn from the Register of Deliveries and integrated with the individual hospital files. We restricted the statistical analysis to 1248 deliveries which occurred between Jan 22, 1993 and Dec 22, 1995, so that we have considered exactly 36 complete lunar months.

The exact time of the lunar phases (month, day, year,

Total spontaneous deliveries

In the first analysis we considered all the spontaneous full-term deliveries (n=1248). The mean direction of the sample results 3.926 rad, corresponding to the 19th day of the lunar month. Table 1 shows the 95% confidence interval of the mean direction and the estimated density function is shown in Fig. 1a.

We applied two tests for the randomness: the general Rayleigh test and the V-test (against a specified mean direction, that we fixed in π direction, corresponding to the full moon). We

Comment

The problem of a possible relationship between the time of delivery and lunar position has aroused the interest of many authors.

In many studies, some events, such as terrestrial magnetism, fluctuations of lunar light and the gravitational pull of the moon upon earth, have been proposed as factors which can alter the time and modality of deliveries. The attempts to demonstrate these hypotheses are numerous and theoretically valuable, but often contradictory.

However, a recent study [13]has

Condensation

A significant connection between the distribution of spontaneous full-term deliveries and the lunar month was found, especially in multiparae and plurigravidae.

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The lunar cycle has long been thought to influence various medical conditions, with evidence both supporting and refuting an effect (Bhattacharjee et al., 2000). Emergency department (ED) visits due to psychologic crisis, suicide, gout attack, and psychogenic non-epileptic seizures have been positively correlated with the full moon (FM), and lunar influence, more specifically FM, may trigger labor (Ghiandoni et al., 1998; Raison et al., 1999; Zargar et al., 2004). Studies have demonstrated that the number of seizures in patients with epilepsy was lowest during FM and highest in the last quarter, and FM showed no statistical correlation with cardiopulmonary arrest frequency, oral and maxillofacial emergency cases, epileptic seizures, ED visits, and the incidence of major trauma (Alves et al., 2003; Benbadis et al., 2004).
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View full text

Does lunar position influence the time of delivery? A statistical analysis

Abstract

Introduction

Section snippets

Methods

Total spontaneous deliveries

Comment

Condensation

Am J Obstet Gynecol

Variazioni mensili, lunari e orarie della frequenza dei parti

Rivista Italiana di Ginecologia

Ist der mond ein Geburtshelfer? Mathematischer Test an 200 000 schweizer Geburten

Nene Zürcher Zeitung

Manefasens innflytelse pa fodsler

Tidsskr Nor Laegeforen

Les rythmes saisonnier, hebdomadaire et lunaire des naissances

Rev Fr Gynecol Obstet

Lunar phase and birthrate: a fifty-year critical review

Psychol Rep

The influence of the moon on deliveries

Am J Obstet Gynecol

Application of mixed Poisson-process models to some Canadian data

Can J Statist

Premature rupture of the fetal membranes, the phases of the moon and barometer readings

Gynecol Obstet Invest