How to Map the Classical Chinese "Ten Months of Pregnancy onto the Biomedical System of Counting Gestational Age
In the past few years, there has been much interest among CM practitioners in information from classical Chinese medical literature on “nurturing the fetus” (養胎). I continue to be struck by the consistency and close textual parallels between texts that differ widely in both time and space, from the Mawangdui silk manuscripts (predating 168 BCE) from Southern China to the tenth century Japanese collection of medieval Chinese literature Ishimpo 醫心方. By contrast, modern authors on this subject in Western languages have sometimes given free reins to their personal creativity, clinical specialization (or blinders, depending on your perspective), or political agenda, to the point where modern information on supposedly traditional Chinese medicine directly contradicts the advice given in the ancient texts. For obvious reasons, this is of great concern to me. Most specifically, the channels and points associated with each month of pregnancy are in the classics clearly identified as PROHIBITIONS. The Ishimpō in particular emphasizes:
During a woman’s pregnancy, the twelve channels are in charge of the fetus. Since it is nurturing the fetus, you must not apply acupuncture or moxibustion to the vessel [nurturing the feuts] during that particular month. Not only does this always damage the fetus, you will moreover rob the mother. You must not be careless! Avoid it in accordance with the month-by-month illustrations [below]…
Sun Simiao is equally clear that one “must not needle or burn moxa on the channel” that nurtures the fetus during each month.
Today’s blog concerns itself with another issue that is often misunderstood or misrepresented, namely how to reconcile the “ten months of pregnancy” in classical Chinese medicine with the average 40 weeks of gestation or three “trimesters” in modern biomedicine. Given the fact that advice in the Chinese classics sometimes differs greatly from one month to the next, it was and still is of great importance to correctly identify the precise timing of each month of pregnancy. While not clear-cut, the answer to this question is surprisingly straightforward, at least in my mind. It obviously hinges on the issue of ovulation, a medical event that is unrecognized and unmentioned in the ancient texts. As most of you should know, biomedicine calculates the gestational age of the fetus by adding two weeks to the actual age of the embryo or fetus. In other words, it counts the length of pregnancy starting from the onset of the woman’s last menstrual period (LMP). How does this match the Chinese ten months? How and when did the ancient Chinese identify the precise beginning of a woman’s pregnancy? Short of visiting Sun Simiao’s grave and hoping for a personal audience in a dream or vision, the best I can do is look in his writings.
Interestingly, but not very helpful, the section in the Qianjinfang on “nurturing the fetus” (千金方II.3) starts out: “The ancient theories all agree that during the three months of receiving the fetus (受胎三月), it will transform according to things and its disposition and character are not yet fixed.” For information on when exactly the process of “receiving the fetus” was initiated, we need to look elsewhere: In the Mawangdui text Taichanshu 胎產書 (Writings on Pregnancy and Childbirth) the Great Yu receives the following advice on reproduction from a person named “Youth Multiplier” (You Pin 幼頻):
When the fluids associated with menstruation have stopped, follow up on this [by having intercourse] over the next three days, and there will be a child. [Having intercourse] on the first day [will result in] a male, [having intercourse] on the second day in a female…
Similarly, the essay on sexual cultivation (“Supplementing and Boosting in the Bedchamber” 房中補益 in the volume on “Nurturing the Inner Nature” (千金方 27.8) explains:
“ If you want to obtain a child [during sexual intercourse], simply wait for the first, third, or fifth day after the woman’s menstrual period [is concluded] and select a wang xiang day (王相日, i.e., an auspicious calendrical date). The time of generating qi must be after midnight and ejaculate only afterwards, and all the children born will be male and are bound to be blessed by long life, sagehood, illumination, and high rank. If ejaculation takes place on the second, fourth, or sixth day after the end of menstruation, all the children born will invariably be female. Once you have gone past six days [after the end of menstruation], you must not ejaculate, or you will not receive a child or [the fetus] will not mature into a full human.
In conclusion, the simple answer to the seemingly simple question on how to map modern gestational age to the ancient Chinese way of counting pregnancy in ten months is therefore anything but simple and frustratingly vague: While modern biomedicine begins counting the gestational age of the embryo or fetus from the ONSET of the last menstrual period, classical Chinese texts begin counting roughly a week later, ideally one or two days after the CONCLUSION of the last menstrual period. In other words, the first month of pregnancy in traditional China would start from what we count as the second week of gestational age, or a week before biomedicine would consider ovulation to have taken place. How exactly you translate this information into your clinical practice shall be left to your discretion.