menstrual cycle vs. lunar phases

There are many claims in modern culture to a relationship between the menstrual cycle and lunar phases. We chose a few to illustrate our point. As we will show, these claims give no scientific evidence, nor were we able to find any in our research. In fact, many of the claims are false and can be disproved by a greater understanding of the two separate cycles.

The Lunar Effect:

In his book of the above title, published in 1978, Arnold L. Lieber, M.D., puts forth the idea that celestial bodies, specifically the moon, effect just about every aspect of human life, including the menstrual cycle. Dr. Lieber calls human's reaction to the moon the "lunar response" and believes it is "a consequence of [land animals] evolution from marine to land-dwelling creatures. At one time, all earthly organisms were marine and influenced by the tides" (49-50). He uses the example of the palolo worm of Samoa and Fiji to show how the phase of the moon influences the reproductive cycle. In this case, the worms, which live inside coral reefs, mate only on the night before the last quarter of the moon in October and November (Lieber, 51). The connection between human women and Fijian worms is left for the reader to make.

Lieber uses the data of previous studies on the relationship between the menstrual cycle and the lunar cycle to prove his point. He quotes the results of Walter and Abraham Manager, whose study was published in 1959 in an unknown journal:

"They used a massive data base. Examining existing studies on the duration of the menstrual cycle, they found that, on the average, the human menstrual cycle is not approximately the same length as the lunar month-- it is exactly the same length, twenty-nine and one-half days (52)."

Unfortunately, this is all that is said. No further reference to the data is mentioned. Dr. Lieber simply "speculates" on how the "lunar-timing component comes into play (53)."

A woman, or "girl-child" is effected by biological tides from the moment of conception. During gestation, the fetus is in equilibrium with the biological ryhthms of the mother. It is the timing of the actual birth that Dr. Lieber claims is important. It is at this time the newborn's rhythms are all her own. His theory is that the forces that regulate all biological rhythms, but especially those of the menstrual cycle, are cued up to the exact moment of birth, which he dubs the time of "cosmic configuration" (54). Proof of this theory and how it would relate to menstruation and ovulation are proved by Dr. Eugen Jonas who believes that ovulation occurs not once, but twice a month. First at the cosmic configuration and again at the configuration that is 180 degrees opposite. This makes the times of ovulation different for each month, following the progression of the moon (Lieber,55).

Lieber ends his chapter with further support of the general relationship women, as opposed to men, have with the moon and thus, their own biological tides:

"Because of the complex interplay between hormonal balance and fluid and electrolyte balance, women at certain times during the menstrual cycle may be more susceptible tot he triggering effects of biological tides. During premenstruum, many women experience bloating, tension, and irritability. Transient fluid buildups and electrolyte imbalance occur. The added physiological stress of a biological high tide occurring during premenstruum could result in drastic physical and/or behavioral consequences. It is well documented that women are more susceptible to physical illness and erratic behavior in the few days prior to menses, and that hospital admissions, psychiatric illness, and violent crime are far more frequent then. Male hormones are less involved with fluid and electrolyte balance, and there seems to be no male counterpart of the prementrual-tension syndrome (54)."

I think the generalizations and prejudice sin Dr. Lieber's work speak for themselves.


This web site acts as a portal to all information regarding the process of menstruation. The authors claim that it is designed to throw off the shackles that imprisoned our grandmothers and make the cycle of menstruation a thing to be proud of. They are fighting against the previous, and present, cultural belief that there is something dirty or bad about having a period. Part of the information the site offers is a page concerning the link between menstruation and the moon. Unfortunately it is based on the following statement:

"Women are connected to the moon by our blood, our hormones and our souls" (

The site offers no data to support its claims. It actually refutes science and asks its readers to do the same.

The site supports Dr. Lieber's source, Dr. Jonas, and offers a very general explanation of the two ovulation times a woman can have during each month. The term Natal Lunar Phase Fertile Time. This Natal Fertile Time is determined, as mentioned before, by the angle between the sun and moon at a woman's time of birth. You of course can pay to analyze your date and time of birth, and menstrual cycle dates and provide you with your own personalized Basic Natal Lunar Phase Fertility Report (

Unfortunately, the attempts of the authors of to enlighten women around the world in order to facilitate a revolution for the often maligned period fail. The very inclusion of unsupported claims just further the problems that accompany the plight of the period in modern cultures. The misinformation just furthers ignorance.


Basic Facts:

  • Lunar Synodic Cycle = 29.53 days (Universe, )
    Menstrual Cycle = 20-40 days (Bio, 925)
    If the menstrual cycle of a woman with even the touted average of a 28 day period were regular, she would still not have her period during the same phase of the moon each month.
  • Only 30% of women have cycles lengths within a day or two of the statistical average of 28 days.
  • Human women are not Fijian worms.
  • Science and knowledge should be free... anyone trying to convince you of a fact who also attempts to charge you for an explanation should be questioned.