Niddah 30-31 ~ Talmudic Obstetrics

Let’s go back to some of the Talmud we studied last week in the daf yomi one-page-a-day cycle, and catch up with some topics we didn’t have a chance to cover.

1. Which fetus grows quicker, Male or Female? (The male)

In the Mishnah (30a) there is a dispute between Rabbi Yishmael and the rabbis about the length of time it takes for a fetus to reach a milestone of completion.

רבי ישמעאל אומר יום מ"א תשב לזכר ולנדה יום פ"א תשב לזכר ולנקבה ולנדה שהזכר נגמר למ"א והנקבה לפ"א וחכ"א אחד בריית הזכר ואחד בריית הנקבה זה וזה מ"א

Rabbi Yishmael said…the formation of the male offspring concludes on the forty-first day and the formation of the female offspring concludes on the eighty-first day. And the Rabbis say: both a male and female fetus concludes on the forty-first day.

In one respect, both the rabbis and Rabbi Yishmael were incorrect: the fetus is not fully formed, or fully anything by the forty (ot the forty-first day). Here is what a human embryo looks like at about four weeks (28 days), six weeks (42 days) and seven weeks (49 days). Does one stage look any more “complete” than another?

Human embryo at about 28 days.

Human embryo at about 40 days. It is about 11mm long.

Human embryo at about 46 days. All images are from From Nilsson, Lennart. A Child is Born. Delacorte Press/Seymour Lawrence. 1990.

But in another respect Rabbi Yishmael was certainly correct and the rabbis were wrong: the male and female fetus do grow at different rates. Back in the late 1960s scientists suggested that the greater the antigenic differences between mother and fetus, the greater is the fetal growth rate. In other words an (XY) male fetus grows at a quicker rate than a (XX) female fetus because an XY fetus is more different from its XX mother than is an XX fetus.

It is well known that, on average, boys weigh slightly more than girls at birth. Less known is the fact that when in utero, boys grow at a quicker rate than girls. For example the diameter of the fetal head (called the biparietal diameter) is larger in male fetuses than in the female, and this difference becomes statistically significant at 24 weeks. Head circumference is also larger for males and becomes significantly greater than that of the female fetus at 24 weeks' gestation.

Head circumference (centimeters) as a function of gestational length (weeks) in both male (•) and female (o) fetuses. From Parker A et al. The ultrasound estimation of sex-related variations of intrauterine growth. Am. J. Obstet. Gynecol 1984. 149:665-669.

To conclude: the evidence supports Rabbi Yishmael to the degree that later in utero boys do grow at a slightly quicker rate. However, there is no difference between growth rates before about 24 weeks, and certainly at a forty day cut-off both male and female fetuses are identical. With a generous reading, that supports the opinion of the rabbis.

Very much related to this topic is the story told on the same page of Talmud about Cleopatra and her cruel experiments on young women.

נדה ל, ב

אמרו לו לר' ישמעאל מעשה בקליאופטרא מלכת אלכסנדרוס שנתחייבו שפחותיה הריגה למלכות ובדקן ומצאן זה וזה למ"א אמר להן אני מביא לכם ראייה מן התורה ואתם מביאין לי ראייה מן השוטים 

They said to Rabbi Yishmael: There was an incident involving Cleopatra, Queen of Alexandria. Since her maidservants were sentenced to death by the government, she took advantage of the opportunity and experimented on them to determine the amount of time it takes for an embryo to develop. She had her maidservants engage in intercourse and operated on them following their execution in order to determine the stage at which an embryo is fully formed, and found that both in this case, when the embryo is male, and that case, when it is female, the formation is complete on the forty-first day after conception. Rabbi Yishmael said to them in response: I bring you proof from the Torah, and you bring me proof from the fools?

Not really. A forty day male and a forty female embryo are visually indistinguishable. The reproductive tract begins to develop in the sixth week of the embryonic period, and external genitalia develop during the 8th-14th weeks of gestation. However, external determination of sex is not possible before urogenital modeling is complete, which also occurs between the 8th and 14th weeks. In the hands of an expert ultrasound operator, sonographic determination of fetal sex has been reported as early as 11 weeks’ menstrual age, “but it may be obtained reliably only as early as 12 to 13 weeks.” (The challenge is distinguishing “between a small penis and a prominent clitoris and between minimally edematous labia and a small scrotum filled with spongy connective tissue.” Now you know.)

In the course of a series of challenges to the opinion of Rabbi Yishmael, the Talmud cites the forth century sage Abaye. He suggests that by examining certain of their anatomical characteristics we can determine if two fetuses were a similar age (“אמר אביי בסימניהון שוין”).  He does not define those “characteristics” but Rashi, the eleventh century commentator does.

בסימניהון שוין - נקבה שנמצא ליום פ"א לא היו אבריה ושערה וצפורניה אלא כשיעור של זכר ליום מ"א

Identical characteristics: The limbs, hair, and nails of an 81 day-old female fetus are as developed as those of a 41 day-old male fetus.

There is a problem here. Fingernails only begin to start to develop around day 70 and toenails around day 100. Neither are present at day 40. Hair develops between weeks 7-12. So the claim that either was clearly present in a 40 or 80 day embryo is not possible.

2. How does the uterus grow?(It stretches)

נדה לא, א

תנו רבנן שלשה חדשים הראשונים ולד דר במדור התחתון אמצעיים ולד דר במדור האמצעי אחרונים ולד דר במדור העליון וכיון שהגיע זמנו לצאת מתהפך ויוצא וזהו חבלי אשה 

The Sages taught in a baraita: During the first three months of pregnancy, the fetus resides in the lower compartment of the womb; in the middle three months, the fetus resides in the middle compartment; and during the last three months of pregnancy the fetus resides in the upper compartment. And once its time to emerge arrives, it turns upside down and emerges; and this is what causes labor pains…

Here is what actually happens. The fetus does not occupy different parts of the uterus as it grow. Instead, the uterus itself expands to accommodate the fetus. In a woman who has never been pregnant, the uterus is about 7-8cm long, around the size of a fist. It grows as the fetus develops, reaching up into the abdominal cavity. At 24 weeks’ gestation, the top of the uterus is at the approximate height of the umbilicus, and by the end of pregnancy it may be felt a little below the lower end of the breast bone.

In contrast, the Talmudic description of the baby turning is correct. The baby floats in a heads-up position until the very last couple of weeks of the pregnancy, when it does a 180 degree flip. About 4% of babies refuse to undertake these gymnastics, and remain heads-up, in what is called a breech presentation.

3. who causes worse labor pains, boys or girls?(They are equal OFFENDERS)

נדה לא, א

היינו דתנן חבלי של נקבה מרובין משל זכר 

 The labor pains experienced by a woman who gives birth to a female are greater than those experienced by a woman who gives birth to a male…

…מאי שנא חבלי נקבה מרובין משל זכר זה בא כדרך תשמישו וזה בא כדרך תשמישו זו הופכת פניה וזה אין הופך פניו 

…The Gemara asks: What is different about the labor pains experienced by a woman who gives birth to a female, that they are greater than those experienced by a woman who gives birth to a male?The Gemara answers: This one, a male fetus, emerges in the manner in which it engages in intercourse. Just as a male engages in intercourse facing downward, so too, it is born while facing down. And that one, a female fetus, emerges in the manner in which it engages in intercourse,i.e., facing upward. Consequently, that one, a female fetus, turns its face around before it is born, but this one, a male fetus, does not turn its face around before it is born.

It wasn’t just the rabbis of the Talmud who believed girls caused their mothers more pain during childbirth. Here is Aristotle (d. 322 BCE), in his Historia Animalum (Book 7 Chapter 4):

As a general rule women who are pregnant of a male child escape comparatively easily and retain a comparatively healthy look, but it is otherwise with those whose infant is female; for these latter look as a rule paler and suffer more pain…nevertheless the rule is subject to exceptions.

LEFT: Face down (OA) presentation. Right: Face up (OP) presentation. From here.

When a baby is born face down, that is to day facing the mother’s back, it is said to be in the occipital anterior (OA) position. This is the most common presentation. When the baby is born face up, that is to say facing the mother’s front, it is said to be in the occipital posterior (OP) position. That presentation is less common. In 2005 a group from the Departments of Obstetrics and Gynecology at the Brigham and Women’s Hospital and Boston Medical Center conducted a prospective cohort study of 1,562 women to evaluate changes in baby’s position during labor. They reported that 80% of the babies were delivered OA, 8% were OP and 12% were in the in-between transverse position. Now what about the Talmud’s suggestion that girls are not born face down, or as an obstetrician would say, in the OA position, but rather face up? Take a look for yourself at the results of the study:

Demographic and Pregnancy Characteristics of 1,572 births. From Lieberman E. Davidson K, Lee-Parritz A. Shearer E. Changes in Fetal Position During Labor and Their Association With Epidural Analgesia. Obstetrics & Gynecology 2005. 105 (1): 974-982.

As you can see, boys made up 58% of the face down births and only 49% of the face up births. So although the Talmud’s suggestion that all boys are born face down is not correct, it is certainly the case that slightly more boys than girls are born in this presentation, at least according to this study. However a 2017 Israeli study (which looked at babies with large heads) found that boys made up 51% of the face down births, and 49% of the face up births, which was a statistical wash.

What about pain? If the Talmud is correct, then the face-up (supposedly female) presentation should be more painful than the face-down (supposedly male) one. Is it? Well, no. The Boston study found that mothers face up baby at delivery did not report more painful labors. They had a mean pain score of 4.9 out of 10, compared with 5.2 for other positions - a non statistical difference.

4. Is intercourse during pregnancy harmful?(No)

נדה לא, א

תנו רבנן שלשה חדשים הראשונים תשמיש קשה לאשה וגם קשה לולד אמצעיים קשה לאשה ויפה לולד אחרונים יפה לאשה ויפה לולד שמתוך כך נמצא הולד מלובן ומזורז 

The Sages taught in a baraita: During the first three months of pregnancy, sexual intercourse is difficult and harmful for the woman and is also difficult for the offspring. During the middle three months, intercourse is difficult for the woman but is beneficial for the offspring. During the last three months, sexual intercourse is beneficial for the woman and beneficial for the offspring; as a result of it the offspring is found to be strong and fair skinned.

תנא המשמש מטתו ליום תשעים כאילו שופך דמים מנא ידע אלא אמר אביי משמש והולך (תהלים קטז, ו) ושומר פתאים ה' 

The Sages taught in a baraita: With regard to one who engages in intercourse with his wife on the ninetieth day of her pregnancy, it is as though he spills her blood.The Gemara asks: How does one know that it is the ninetieth day of her pregnancy? Rather, Abaye says: One should go ahead and engage in intercourse with his wife even if it might be the ninetieth day, and rely on God to prevent any ensuing harm, as the verse states: “The Lord preserves the simple” (Psalms 116:6).

Contrary to the Talmud’s assertion, there is no association with the frequency of intercourse during pregnancy and the danger of a miscarriage. Here is what the Mayo Clinic tells patients:

Your developing baby is protected by the amniotic fluid in your uterus, as well as by the strong muscles of the uterus itself. Sexual activity won't affect your baby, as long as you don't have complications such as preterm labor or placenta problems…

Having sex during pregnancy won't provoke a miscarriage. Most miscarriages occur because the fetus isn't developing normally.

“יש ניהגיס כשנכנסה אשתו בחדש ט׳ לעיבורה לעשות בחדש ההוא מצות פתיחת ההיכל והוא מנהג יפה

There is a custom during the ninth month a woman’s pregnancy to give her husband the mitzvah of opening the ark. And this is a good custom”

— כף היים ס ׳ קלד, יב By Rabbi Yaakov Chaim Sofer, (1870-1939).

You may have heard about a Jewish folk remedy (a segulah) believed to help start the process of labor in a woman ready to give birth. It is to give her husband the honor of opening the ark during the service in the synagogue. I am not aware of any randomized clinical trial of the belief, but there have been randomized trials of another claim, this one perhaps a little more widespread. That claim is that intercourse late in pregnancy will induce labor.

It goes way back to Aristotle in the fourth century BCE, who wrote that “women who have a connection with their husbands shortly before childbirth are delivered all the more quickly.” However Soranus, another Greek physician who lived in the third century CE (and about 500 years after Aristotle) believed that any intercourse during pregnancy was harmful. Here is what he wrote in his textbook of gynecology:

Sexual intercourse however is always harmful to pregnant women both on account of the tossing motion and because the uterus is forced to submit to a movement which is contrary to the progress of pregnancy. And even more so in the last months lest because of it the chorion burst and the fluid which has been prepared for use in parturition be evacuated before the proper time.

“It is important to find a scientific answer to this issue” wrote a team of researchers in Portugal, “because if it is proven to be true, a decrease in the number of medical interventions for post-term pregnancy can occur.” So they randomized pregnant women to two groups: “vaginal intercourse at least twice a week or abstinence.” Yes, you read that correctly. 63 women and their lucky partners were assigned to the intervention group and 60 to the control. And there were no significant differences between the rates of spontaneous onset of labor in the two groups. A 2019 review from the School of Medicine in Naples Italy concluded that “in women with singleton [i.e. not twins], cephalic [head down], low-risk pregnancies, sexual intercourse at term does not significantly increase the incidence of spontaneous onset of labor.” So that myth is now officially busted.

Next time, on Talmudology: The Zov and Gonorrhea.

Niddah 32a ~ Neonatal Menstruation

In this midst of a complex discussion of the laws of ritual impurity as they apply to an adult woman, the Talmud notes that the same laws apply to a new born infant girl.

נדה לב, א

אשה אין לי אלא אשה תינוקת בת יום אחד לנדה מנין ת"ל ואשה

What is this interpretation of the difference between “a woman” and “and if a woman”? As it is taught in a baraita that from “a woman” I have derived only that the halakhot of menstruation apply to an adult woman. From where do I derive that the halakhot of a menstruating woman also apply to a one-day-old girl? The verse states: “And if a woman.” [when the verse includes young girls through the word “and” it includes even a one-day-old.]

From here.

This ruling is codified by Maimonides in his Mishneh Torah: “קְטַנָּה בַּת יוֹם אֶחָד מְטַמָּא בְּנִדָּה”. By this point you may be asking what case could the Talmud possibly be discussing? And the answer is: a real case.

Don’t Panic - it is not unusual

While it is unlikely that you have previously encountered the phenomenon of newborn menstruation, it is a very well described medical condition. In the English literature it is called “neonatal uterine bleeding” (NUB) or “neonatal menstrual-like bleeding” (NMB;) French authors refer to it as “la crise genitale du nouveau ne” and the Germans as “Neugeborenen genitalkrisen” which is useful to know, I suppose, should you find yourself in Europe with a baby girl who has this condition.

In a review paper titled “Is my baby normal? A review of seemingly worrisome but normal newborn signs, symptoms and behaviors” the authors, who were pediatric emergency physicians (meaning they looked after children - the doctors were themselves were, I think, adult-) noted that

Hormonal fluctuations in the neonatal period can result in changes in the genitourinary area that are concerning to parents. Female infants may experience scant vaginal bleeding due to hormonal withdrawal between the third and seventh day of life.

And here is how the very popular site WebMD explains what is going on:

At 2 or 3 days of age, your daughter may have a little bit of bleeding from her vagina. This is perfectly normal; it is caused by the withdrawal of the hormones she was exposed to in the womb. It will be her first and last menstrual period for another decade or so.

And that’s pretty much all there is to say. It is caused by a progesterone withdrawal in the little girl.

Incidentally there is another phenomenon that is somewhat related. Sometimes new-born baby girls will produce milk from their nipples (and sometimes it can happen in a baby boy). This is called “witchs’ milk,” although the correct medical term is galactorrhea. One study found it in 6% of 640 baby girls examined over a five-month period. It too is a normal finding, caused by the baby’s absorption of her mothers hormones, in this case prolactin, and it usually resolves with a month.

Neonatal uterine bleeding and other problems

So although it is a normal finding in a newborn girl, there is some evidence that neonatal menstruation may be an indicator of gynecological problems that will arise later in life. For example, it may be linked to early-onset endometriosis, a condition in which cells similar to the lining of the uterus grow outside of it, most commonly in the ovaries, but sometimes in the abdomen. And it has also been associated with fetal distress and low birth weight.

Summing this up in the European Journal of Obstetrics & Gynecology and Reproductive Biology, two researchers argued for more research in this phenomenon.

First, available evidence clearly indicates that neonatal bleeding is a menstruation characterized by progesterone withdrawal. Because feto-maternal factors influencing its frequency (fetal growth restriction, preeclampsia) are characterized by a reduced blood supply to the placenta, it seems that…NMB can therefore be used as a marker of intrauterine distress and, as a sign of fetal distress the bleeding requires to be registered in medical notes of all newborns.

Secondly, NMB may represent a sign of increased risk of developing endometriosis during adolescence and, in turn that this form may be more frequently progressive, as shown by several studies. Registration of NMB will allow prospective studies aimed at validating the application to newborns of the menstrual regurgitation theory.

Thirdly, there is a need to revive scientific interest in the neonatal menstrual-like bleeding; an event that possibly plays a role, among others, in the transgenerational evolution of major reproductive disorders and adolescent endometriosis.

Although neonatal uterine bleeding is not common, it certainly occurs, which is why the Talmud explored its ritual ramifications. We should expect nothing less.

“Today, the bleeding is completely neglected and considered an uneventful episode of no clinical significance”

— Brosens, I.Benagiano G. Clinical significance of neonatal menstruation. European Journal of Obstetrics & Gynecology and Reproductive Biology 2016. 196 57–59

Niddah 31a ~ When is a Woman Most Fertile?

Today's daf stays with the theme of gynecology. The Talmud describes a dispute about when a  woman is most fertile. One opinion is that "a woman only conceives close to her period"  (אין אשה מתעברת אלה סמוך לווסתה), and a second opinion is that "a woman only conceives close to her immersion in a mikvah" (אין אשה מתעברת אלה סמוך לטבילתה).  

Medical students spend many hours learning the hormones whose rise and fall causes ovulation.  But understanding the ovulation cycle is the key to understanding this passage in the Talmud, so let's spend a paragraph on...

Ovulation in Humans

There are two important hormones that regulate ovulation in a human. One is called Follicle Stimulation Hormone, or FSH. This is produced in the pituitary gland deep in the brain and it acts on the ovaries to produce follicles, which are little groups of cells that may produce an egg. Under the action of FSH, the ovaries produce many follicles, but usually only one will go on to produce and release an egg. (If more than one follicle releases and egg, and both are fertilized, the result is non-identical twins.)  

A sudden spike in FSH and another hormone called Luteinizing Hormone (LH) cause the winning follicle to release its egg, which floats down the Fallopian Tube and into the uterus. If the egg meets a sperm cell, they unite and start down the pathway to producing a baby. But if no sperm cell is encountered, there is a drop in the level of two other critical hormones, progesterone and estrogen (also known as oestrogen for our British readers). This causes the lining of the uterus to slough off, and menstrual bleeding begins, until the whole cycle begins again.

Diagram from here.

Assuming a twenty-eight day cycle, the FSH-LH peak that trigger ovulation just before or around day fourteen, and ovulation - the release of the egg from the ovaries - occurs soon after.

“Scholars of the ancient world thought that menstruation represented an excess of blood from which the woman must periodically rid herself in order to cleanse her body from noxious substances. Only during the twentieth century has the scientific basis for the menstrual cycle and its hormonal relationships been clarified.”

— Avraham Steinberg. Encyclopedia of Jewish Medical Ethics. Feldehim 2003. Vol II p650.

Counting the Days to Mikveh

As outlined in the Torah (Leviticus 15:19), a menstruating woman is ritually unclean - Niddah - for seven days. After that she undergoes a ritual bathing in a mikveh, and she may resume physical and intimate contact with her husband. However the biblical seven day period was transformed in talmudic and later rabbinic tradition. The result was the addition of another (minimum) of five days to the length of time that a couple must abstain from physical intimacy. As a result, if we assume that day one of the onset of menstruation is the first day of the 28 day average menstrual cycle we discussed above, then the earliest day for a woman to immerse in the mikveh is on day twelve, or two days before ovulation is likely to occur.

The length of the menstrual cycle varies to a remarkable degree among different populations and in different age groups. In women age 19-41 in the US it varies from about 23 to 38 days (with a mean of 31 days.) In Danish women aged 20-35 however, the cycle is about 26-31 days, with a mean of 28 days. And each different cycle length will have its own ovulation day, and each varied ovulation day will effect the day on which conception is most likely.

Cycle length distributions for selected samples from various human populations. The numbers at the far left of each sample identify the corresponding sample and data. From Amy L. Harris & Virginia J. Vitzthum. Darwin's Legacy: An Evolutionary View of Women's Reproductive and Sexual Functioning, The Journal of Sex Research 2013. 50:3-4, 207-246.

The Timing of Sexual Intercourse and the Probability of Conception

The next issue in deciding which of the two opinions in today's page of  Talmud might be correct is this:  on which days around ovulation is a woman most fertile?  This question was addressed in a study published in the esteemed New England Journal of Medicine in 1995. The authors followed 221 healthy woman who were trying to become pregnant (for a total of 625 menstrual cycles!!).  The women kept records of when they had sexual intercourse, and their urine was tested for hormone metabolites to estimate the day of ovulation.  The study found that  "conception occurred only when intercourse took place during a six-day period that ended on the estimated day of ovulation." The authors note that couples who abstain from sexual intercourse until they have evidence of ovulation may miss the opportunity for conception.   

Probability of Conception on Specific Days near the Day of Ovulation.
The bars represent probabilities calculated from data on 129 menstrual cycles in which sexual intercourse was recorded to have occurred on only a single day during the six-day interval ending on the day of ovulation (day 0). The solid line shows daily probabilities based on all 625 cycles, as estimated by a statistical model. From Wilcox A. et al. Timing of sexual intercourse in relation to ovulation. N Engl J Med 1995;333:1517-21.

As you can see in the graph below, the day on which women are most likely to conceive is two to three days before ovulation. This is independent of their age.

Fertile window for four age groups. Probability of conception is highest for an act of intercourse occurring two days prior to ovulation. Redrawn from Dunson et al. (2002). Changes with age in the level and duration of fertility in the menstrual cycle. Human Reproduction, 17(5), 1399–1403, and cited in Amy L. Harris & Virginia J. Vitzthum. Darwin's Legacy: An Evolutionary View of Women's Reproductive and Sexual Functioning, The Journal of Sex Research 2013. 50:3-4, 207-246.

The chances of conception on a random day

In a review of the variability in ovarian function, Amy Harris and Virginia Vitzthum from Indiana University note that although it is the case that the fertile window is fairly narrow (about six days, ending within 24 hours after ovulation) “it does not follow that the fertile window occurs during a narrow range of days during the menstrual cycle. To the contrary, because the timing of ovulation during a cycle is quite variable, women have a 10% or greater probability of being in their fertile window on every day from cycle days 6 through 21, and more than 70% of women are in their fertile window before cycle day 10 or after cycle day 17.”

So they plotted the probability of conception on each cycle day then calculated the mean probability of conception (i.e., clinical pregnancy following a single act of unprotected intercourse on a random day. What they found was that the average probability during cycle days 7-14 was 25% higher than that during cycle days 14-21. The average probability during the first two weeks of the cycle was 16% higher than that during the next two weeks. “Furthermore, in that subset of women who reported having irregular cycles, a not uncommon pattern, length and menses duration), the average probability during cycle days 7-14 is less than half of that during cycle days 14 to 21.”

“Among healthy women trying to conceive, nearly all pregnancies can be attributed to intercourse during a six-day period ending on the day of ovulation. ”

— Wilcox A. et al. Timing of sexual intercourse in relation to ovulation. N Engl J Med 1995;333:1517-21.

This is important.

Panel A: The probability of ovulation by cycle day. Normal variation in the length of the follicular phase of the menstrual cycle: effect of chronological age.

Panel B: Daily probability of conception on each cycle day; mean probability of conception during cycle days 7 to 14= 6% and during cycle days 14 to 21 = 4.8%

Panel C: Daily probability of conception on each cycle day for women reporting regular cycles (thick line) and for those reporting irregular cycles (thin line); in latter sample, the average probability of conception during cycle days 7 to 14 is 2.5% and during cycle days 14 to 21 it is 5.8%.

Halakhic Infertility

Sometimes, as woman may be biologically fertile, but unable to conceive because of halakhic considerations. If a woman has a menstrual cycle that is shorter than the average 28 days (and about 20% of women have just that), or if a woman bleeds for more than 5 days (resulting in a longer Niddah time, in which the couple may not have intercourse) then  - and pay attention to this - then ovulation takes place during the Niddah time. And if that happens, as we noted above, then conception is all but impossible. This might be called halakhic infertility, and it is more common than you might have thought.    

In a study of the prevalence of halakhic infertility in a population of ultra-orthodox Jews seeking help from a fertility clinic, a group from Hadassah Hospital in Jerusalem studied 45 infertile women.  They found that precoital ovulation was prevalent in one-fifth (21%) of the patients.  "Since not obeying the halachic code of conduct is non-negotiable, and in view of the void of halachic solutions, most couples (68%) seek medical advice and treatment."  Fortunately such treatment is available: taking an an oral estrogen can delay ovulation to after the time of mikveh, and allow intercourse to take place at a time when conception is more likely.  

“A fifth of infertile couples were diagnosed as suffering from infertility due to a religious rather than biological cause...This significant proportion of infertile couples who suffer from sociocultural infertility mandates special attention, primarily of the Rabbinate [sic] authorities.”

— Haimov-Kochman R. et al. Infertility associated with Precoital Ovulation in Observant Jewish Couples; Prevalence, Treatment, Efficacy, and Side Effects. Israel Medical Association Journal 14 (2011): 100-103.

Back to the Daf - Which Opinion is Correct?

Let's now return to the question with which we opened; which of the following two opinions is correct?

1. A woman only conceives close to her period(אין אשה מתעברת אלה סמוך לווסתה).

2. A woman only conceives close to her immersion in a mikvah (אין אשה מתעברת אלה סמוך לטבילתה).

The first opinion is most certainly not supported by modern medicine. The second opinion is often likely to be true, but - and this is a BIG BUT - only for women for whom both the menstrual cycle is not short and menstrual bleeding is not long. For a sizable number of women, conception is no longer possible when they are ready to go to the mikveh.

It is a remarkable fact (and one I have never seen addressed or even acknowledged) that orthodox Jewish practice has evolved to permit intercourse only in that part of the menstrual cycle which has a lower chance of conception. As a result, orthodox Jews have become in this respect, halachically subfertile. Fortunately that doesn’t seem to have made much of a dent in their rates of reproduction. “Being Orthodox” wrote Michelle Shain of the Center for Modern Jewish Studies at Brandeis, '“ increases the odds of having any births by a factor of 7.18 and, among women who have given birth, increases the expected number of births by a factor of 6.14.” Remarkably, this is in spite of, and not because of, the laws of ritual impurity that are a foundation of Jewish practice.

Mean expected number of births by age, education and Orthodoxy. From Michelle Shain, Understanding the Demographic Challenge: Education, Orthodoxy and the Fertility of American Jews. Contemporary Jewry 2019. 39: 273.

“Consultation with a Rabbinate [sic] authority was reported by 64% of women, but no halachic solution was provided to any of the applicants. ”

— Haimov-Kochman R. et al. Infertility associated with Precoital Ovulation in Observant Jewish Couples; Prevalence, Treatment, Efficacy, and Side Effects. Israel Medical Association Journal 14 (2011): 101.

Niddah 30b ~ Talmudic Embryology

נדה ל, ב

דרש רבי שמלאי למה הולד דומה במעי אמו לפנקס שמקופל ומונח ידיו על שתי צדעיו שתי אציליו על ב' ארכובותיו וב' עקביו על ב' עגבותיו וראשו מונח לו בין ברכיו ופיו סתום וטבורו פתוח ואוכל ממה שאמו אוכלת ושותה ממה שאמו שותה

Leonardo Da Vinci. Studies of the Fetus in the Womb. Drawn between 1510-1513.

R. Simlai delivered the following discourse: What does an embryo resemble when it is in the bowels of its mother? Folded writing tablets. Its hands rest on its two temples, its two elbows on its two legs and its two heels against its buttocks. Its head lies between its knees, its mouth is closed and its navel is open, and it eats what its mother eats and drinks what its mother drinks...

Talmudic embryology reflected the prevailing Greek theories of the times. But those theories developed without the benefit of microscopes and the other tools later available to scientists. Despite this, sometimes the rabbis of the Talmud were spot on with their embryology. Today’s statement of Rav Simlai is a good example. (He lived in 3rd century CE, and is the rabbi who brought you the famous count of 613 commandments.) It is a perfect description of a growing fetus, written as if Rav Simlai was looking at Leonardo Da Vinci’s famous sketch. But his was not the only talmudic description of a how a fetus grows, so let’s look at some others.

Will the real Abba Shaul please stand up?

On page 25a of Niddah Abba Shaul declared that the fetus grows from its head:

נדה כה, א

אבא שאול אומר תחלת ברייתו מראשו

Abba Shaul says: The beginning of the formation of the embryo is from its head

But elsewhere Abba Shaul has a different theory:

סוטה מה, ב

מהיכן הולד נוצר מראשו וכן הוא אומר ממעי אמי אתה גוזי ואומר גזי נזרך והשליכי וגו' אבא שאול אומר מטיבורו ומשלח שרשו אילך ואילך

From where is the fetus formed? From its head, as the verse says (Ps.71:6): "From my mother's womb you pulled me out (gozi)". And it says later (Jeremiah 7:29) "Pull out (gozi) your hair and throw it away.." Abba Shaul says that the fetus is created from its navel, and from there it sends out roots in all directions.

The contradiction between these two statements was noted by the great French medieval commentator Yakov ben Meir, known as Rabbenu Tam (d. 1174). He suggested that there is an error in the text before us: In Niddah, it should not read “from its head (מראשו), but “like a locust” (כרשון). Indeed this is the reading found in the important medieval dictionary Sefer HaAruch and echoed centuries later in Marcus Jastrow’s dictionary.

תוספות נדה כה,א, ד’ה תחלת ברייתו מראשו

תימה דבפ' בתרא דסוטה (דף מה:) קסבר אבא שאול תחלת ברייתו מטיבורו ומשלח שרשיו אילך ואילך ונראה לר"ת דגרס כרשון וכן פר"ח ובתוספתא פירש כעין חגב דסלעם מתרגמינן רשון וכן משמע דמיירי בשיעור האברים

Rabbenu Tam’s explanation makes a great deal of sense and leaves Abba Shaul with only one opinion: the fetus develops from the navel. This is not exactly what actually occurs, but to the naked eye it is not too far from it. Interestingly, Maimonides declined to take a position on the matter, and wrote simply that “at the beginning, the body of a person is the size of a lentil…”(תְּחִלַּת בְּרִיָּתוֹ שֶׁל אָדָם גּוּפוֹ כַּעֲדָשָׁה).

“The Talmudic Sages,being true polyhistors, took into account experimental biology as well as popular beliefs.”

— Kottek S. Embryology in talmudic and Midrashic Literature. Journal of the History of Biology 1981. 14 (2): 299-315.

Embryonic Development in Antiquity

In 1934 the British historian and embryologist Joseph Needham published A History of Embryology, in which he traced theories of embryonic development from from antiquity to modern times. In this fascinating book we learn that Hippocrates (c. 460-370 BCE) believed the fetus was formed by extracting breath from its mother, and that a series of small fires within the uterus gave rise to the bones and other organs of the embryo. According to Needham, Aristotle (384-322 BCE) understood that the role of the umbilicus was to nourish the fetus. The vessels of the umbilicus join onto the uterus like the root of a plant and through the cord the fetus receives its nourishment. Elsewhere, Aristotle claimed (contra Abba Shaul) that head of the fetus forms first. Galen (c. 129-216 CE) also used the analogy of the umbilicus serving like the root of a plant. According to him the embryo grew from menstrual blood, and then from the blood that nourished it through the umbilical cord.

What Actually Happens -not from THE head or from the navel

Development of the Umbilical cord. A: The posterior body wall is established. B: the vitelline duct form as the cells form a head and tail end, fold inwards on their lateral sides. C: The umbilical cord forms as the yolk sac and vitelline duct fuse. From O'Donnell K. Glick P, Caty M. Pediatric Umbilical Problems. Pediatric Clinics of North America. 1988 24 (1) 792.

At its earliest stage the embryo consists of a sheet of cells, an amniotic cavity and a yolk sac. The sheet of cells develops a head (cranial) and bottom (caudal) end, and grows around most of the yolk sac. This enclosed yolk sac then grows into the gut of the embryo.  The part of the yolk sac that is not surrounded by the embryo is still connected to it by a thin tube called the vitelline duct.  This duct then fuses with the contained yolk sac, and forms a larger bundle of vessels we call the umbilical cord. This occurs between the 4th-8th week of gestation (calculated from the first day of the last menstrual cycle).  

It is clear then, that the embryo does not grow from the head or from umbilical cord.  As you can see from the diagram, the head develops from the early cells of the embryo as it takes on a cranial-caudal polarity, sometime around 3-4 weeks gestation, when the embryo is about 3mm in length. Neither does the embryo grow from the umbilical cord, as Abba Shaul claimed. In fact it is the umbilical cord that grows out from the early embryo, and not the other way around.

However well understood the process of fetal development may now be, pregnancy remains a time that is often fraught with uncertainty and insecurity. The rabbis of the Talmud articulated these fears with a prayer, that reminds us of the fragility of human development and the relief when it all goes well.

ברכות ס,א

שלשה ימים הראשונים יבקש אדם רחמים שלא יסריח משלשה ועד ארבעים יבקש רחמים שיהא זכר מארבעים יום ועד שלשה חדשים יבקש רחמים שלא יהא סנדל משלשה חדשים ועד ששה יבקש רחמים שלא יהא נפל מששה ועד תשעה יבקש רחמים שיצא בשלום

During the first three days after intercourse, one should pray that the seed not putrefy, [that it will fertilize the egg and develop into a fetus].

From the third day until the fortieth, one should pray that it will be male.

From the fortieth day until three months, one should pray that it will not be deformed, in the shape of a flat fish,

From the third month until the sixth, one should pray that it will not be stillborn.

And from the sixth month until the ninth, one should pray that it will be emerge safely.

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Next time on Talmudology: When Is a woman most fertile?