We are including below a response that we sent to another reader a few years ago which deals with your question. Please accept our apologies for the delay.

Be well,

Kollel Iyun Hadaf

====================================================

Yonason Sigler asked-

The Gemara (Berachos 60a) states that up until forty days after conception, it is not a Tefilas Shav to pray that one's pregnant wife should bear a male child (in the instance that Hizri'u Sheneihem b'Vas Achas).

How is this consistent with modern science that maintains that the baby's gender is determined from the moment of conception?

Rav Joseph Pearlman replied-

Although this could be the case that "Nishtanu ha'Tiv'im," I do not think we need to come on to that solution in this case. It seems to me that here we are encountering the enormous potential in Tefilah. Whatever the biological position might be, this Gemara is teaching us that Tefilah of the right potency has the inherent ability to change the natural order of events. This is also implicit from TOSFOS in Sanhedrin 22a, DH Arba'im, that although one's marriage partner is determined 40 days before the formation of the embryo, nonetheless prayer can effect a transversal from one gender to the other.

After 40 days, however, even though it is possible for the same thing to take place, the Gemara makes it clear that one must not do so since "Ein Mazkirin Ma'aseh Nisim." The VILNA GA'ON explains, in Shenos Eliyahu to Berachos 9:1, that "[a prayer] for even something that is possible to occur, but only through a miraculous manner and not through the natural order, is considered a Tefilas Shav, a prayer in vain." The MISHNAH BERURAH explains that "the form of the embryo has already been fashioned, but within 40 days Tefilah is effective."

The Midrash Tanchuma (Vayetzei 8, to Bereishis 30:21) assumes that it can take place right up to the onset of the birth process, and so, too, the Yerushalmi (Berachos 9:3, "d'Veis Yanai Amri be'Yosheves Al ha'Mashber"). See in this context the sources quoted and discussed in TORAH SHELEIMAH to Vayetzei (Bereishis 30:67-8), ALEI TAMAR to Yerushalami Berachos (loc cit.), the fascinating discussion on the Halachic literature in relation to abortion during the first 40 days of pregnancy in Contemporary Halachic Problems (by Rabbi J. D. Bleich), vol. I, pp. 325-371, and particularly p. 339, and in vol. II, p. 92 (copy attached).

During the first 40 days, however, all agree that the incipient embryo has the status of "Maya b'Alma" for a number of purposes. Hence, the prayer will be acceptable and efficacious, since any such change would not be recognizable at all as a miracle, whatever the true biological position. Should it become recognizable by modern advanced testing processes, then there would be a strong argument that prayer for the sex change should no longer be permitted, since we would then be impinging on the prohibition of asking for Ma'aseh Nisim Geluyim. On the other hand, there is a Halachic ruling that during the first 40 days the embryo is insufficiently formed to constitute any independent identity; see Yevamos 69b and Nidah 30a, etc. Thus we come to the old question of to what extend the traditional Halachah can contradict scientific facts.

Perhaps the answer in this case is that it is permissible to pray for the embryo to be make provided that it not and will not be tested. In such case no one can ever know whether it was originally female at conception, and as it is "Maya b'Alma," the prayer cannot be seen to be a miracle, or even any contradiction to the facts. However, after 40 days the embryo is clearly defined and the prayer becomes a Tefilas Shav, as it is by then apparent that it is either already male or female, and a sex change at this stage is too miraculous an event for us to pay for it to happen.

Incidentally, on a connected subject of "Ish Mazri'a Rishon, Yoledes Nekevah," etc. (Nidah 25b and quoted by Rashi in Parshas Vayigash (Bereishis 46:15)), which seems biologically unintelligible (see Torah Temimah to Parshas Tazria 12:1:5), and see ArtScroll on Nidah, who suggests that a woman also gives forth seed, which does not tally with known facts), I was once shown an article many years ago whereby the Gemara can be remarkably reinterpreted to accord with the most advanced scientific research. That article's thesis could well be what the Gemara means by "Ishah Mazra'as Techilah, Yoledes Zachar." See "How to Choose the Sex of Your Baby," an article by Roger A. Hunt, Copyright 1996 (based on _How to Choose the Sex of Your Baby_, by Dr. Landrum B. Shettles, MD, and David M. Rorvik. Published by Doubleday & Co.; copyright 1984).

Perhaps regarding our "Arba'im Yom" situation, science will also come up with something which will show that the Gemara does in fact fit in with the biological facts. Perhaps science is mistaken in that though it appears as if the sex is determined at conception, there remains the vestigial possibility of a valid change for the first forty days. It should not be so difficult to accept that the "Maya b'Alma" of the embryo is not necessarily irrevocably determined at conception. Perhaps there is some available internal fluid or chemical reaction yet unknown to scientists which might alter the gender by a perfectly natural process at this earliest stage of embryonic formation and development and it is this that Tefilah can activate. (Ed. note: See quotation below, which supports Rav Pearlman's proposal. -YS)

Joseph Pearlman

Changing the sex of the embryo within 40 days

"A crucial event that determines whether the embryo will develop into a male or female occurs in the second half of week six. If the Y chromosome is present in the embryo's cells, a gene within the short arm of the chromosome called SRY will turn on, initiating a chemical chain reaction that will turn on other genes and stimulate the production of male hormones. If the X chromosome is present, or if the SRY gene is missing from the Y chromosome, the embryo will develop into a female via mechanisms that are not fully understood. (Note: SRY stands for sex-determining region of the Y chromosome.)"

(-From http://www.pbs.org/wgbh/nova/gender/dete_nf06.html). Note that the above paragraph is discussing the second half of week six! )

Yonason Sigler comments-

To Rav Joseph Pearlman and all the very esteemed Talmidei Chachamim of Kollel Iyun HaDaf,

It was an honor to receive such a thorough and timely response to my inquiry. My response is not thorough and certainly not timely, but I submit it anyway, hoping that it will in some small way advance the discussion.

Rav Pearlman writes: "During the first 40 days, however, all agree that the incipient embryo has the status of 'Maya b'Alma' for a number of purposes. Hence, the prayer will be acceptable and efficacious, since any such change would not be recognizable at all as a miracle, whatever the true biological position."

The idea expressed here -- namely, that prayer can in fact effect radical physical changes, so long as these changes are not observable and therefore do not constitute a revealed miracle -- is essentially the assumption underlying the Midrash Tanchuma and Yerushalmi referenced in the previous paragraph which hold that changes can occur up to the "onset of the birth process."

While this is certainly a valid assumption and, in fact, has its place in modern day Hora'ah (it is well known that the Steipler Ga'on zt'l would advise his petitioners who were ill to avoid excessive diagnostic testing, because once an illness had been diagnosed conclusively, the cure would have to be more or less miraculous, depending on the illness), I don't believe this is the operating assumption of our Gemara given that an embryo even after day 40 is not recognizable externally as even existing ("Hukar Ubra"), let alone observing its gender, and yet the Gemara states that after day 40, to Daven for a gender change would be a Tefilas Shav.

At this point it could be suggested, in an effort to support Rav Pearlman's suggestion, that our Gemara does essentially accept the assumption of the Midrash Tanchuma with the following refinement: Whereas according to the Midrash it is enough that the object under discussion -- in this case, a fetus -- be concealed from observation ("Samuy Min ha'Ayin"), according to out Gemara the true nature of the thing must be essentially undetectable with the unaided human senses. Therefore, according to the Midrash it is enough that the fetus is concealed from sight by the mother's body, whereas according to our Gemara this is not enough to be considered "Samuy Min ha'Ayin," rather it has to be intrinsically concealed from observation, which is only the case in the first forty days before the external signs of gender begin to develop; before that stage of development, it would require microscopic observation of the genetic material to determine the gender, and therefore Tefilah is effective.

I see, though, no reason why there should be such a distinction (Chiluk) made by our Gemara between effective concealment and intrinsic concealment. Furthermore, why should there be a condition (Tenai) of b'Vas Achas? If it is concealed, that should be enough. (The condition (Tenai) of b'Vas Achas suggests that there is some altered physical state, which science is unaware of, which removes the determinedness of gender.)

Incidentally, the Halachic ruling that during the first 40 days the embryo is insufficiently formed to constitute any independent identity, sighted in Yevamos 69b and Nidah 30a, poses no difficulty to us because it is certainly reasonable to assume that, even though the gender is determined at conception, based on the genetic makeup of the embryo, there are specific Halachos -- for example, Tum'as Leidah -- which are based ("Geder") on recognizable signs of gender.

In the final paragraph of his response, Rav Pearlman writes, "Perhaps science is mistaken in that though it appears as if the sex is determined at conception, there remains the vestigial possibility of a valid change for the first forty days." It would be foolish to argue with this statement and claim that it is impossible for a change to occur in the first forty days; how many times in the history of science and technology have the naysayers been proven wrong. It certainly is possible; however, we must appreciate the magnitude of the problem facing us.

Whereas for a male embryo to develop into a female fetus it may only require the non-expression of the so-called SRY gene found on the Y chromosome, however for the opposite to occur, a female embryo to transform into a male one, it would require the spontaneous appearance of the SRY gene or some equivalent gene on the X chromosome to set in motion male development. I would be interested to know whether either of these events have ever been observed in nature; that is, a healthy female with a Y chromosome or a healthy male with two X chromosomes. To speculate that the entire Y chromosome transforms into an X chromosome or vice-versa is to move into the realm of the fantastic (but possible!).

Incidentally, the very interesting observation made in your response that the scientific model for gender development corresponds to Chazal's definition of "Maya b'Alma" -- namely that the expression of the gender-causing genes begins shortly before day 40 -- in no way undermines the inherent determinedness of gender from the time of conception. All of the elements necessary for gender development are in place at the time of conception.

Given the difficulties mentioned above, I would offer the following simple observation, and that is that in fact the assumption here that the gender is not strictly determined within the first forty days is the point of dispute between the two answers (Terutzim) given by the Gemara to the original question (Kushya) about the case of Leah and Dina. According to the first Terutz, the gender is in fact strictly determined at conception, and the case of Leah and Dina was a full-fledged miracle (seemingly at odds with the Midrash Tanchuma mentioned above). This position is consistent with the simple, straightforward reading of the Mishnah which makes no distinctions between before or after 40 days. It is also consistent with the simple reading of Rebbi Yitzchak's statement regarding the precedent of seeding without the necessity of introducing a third category (namely, b'Vas Achas).

It is only according to the second Terutz of the Gemara ("I'ba'is Eima") that gender is not strictly determined at conception, in the case of b'Vas Achas, and that the case of Leah and Dina was not miraculous but rather a natural result of Leah's Tefilos. It would seem that this position must be accepted as conclusive given that it is supported by the Beraisa quoted therein ("Sheloshah Yamim ha'Rishonim..."). If, however, one examines the Gemara in Nidah (31a) one finds a Beraisa articulating the same idea as Rebbi Yitzchak's statement ("Ish Mazri'a Techilah..."). We may suggest that the first Terutz holds that the two Beraisos are at odds with each other, and that Rebbi Yitzchak's statement does not need to be modified to conform with the Beraisa in our Gemara. Whereas the second Terutz holds that just as Rebbi Yitzchak's statement can be made to conform with the Beraisa of our Gemara, so, too, the Beraisa of Nidah can as well.

Incidentally, there is support for the position of the first Terutz that what happened in the story of Leah was in fact a miracle. See the very interesting Targum Yonasan ben Uziel on the relevant verse which states that Rachel was pregnant with Dina and Leah with Yosef, and a miraculous swap was made.

The fact that modern empirical observation seems to support one Terutz and not the other should not be surprising. It would be unreasonable to expect it to support both of them given that they are at odds with one another. See the Gemara in Pesachim 94b, where we have a similar situation -- a dispute between the wise men of the nations and our Sages zt'l over the nature of the solar orbit. The dispute is decided in favor of the wise men of the nations by Rebbi Yehudah ha'Nasi based on empirical observation. At least in our case both opinions are those of our Sages zt'l!

Does this mean that in our case one group of Sages simply got it wrong? I don't think so. See the Gilyon ha'Shas there in Pesachim, who brings the opinion of Rabeinu Tam that even though the empirical facts support the wise men of the nations, the true reality is according to the opinion of our Sages zt'l. It seems that what Rabeinu Tam is saying is that the Sages are describing a higher metaphysical reality and that at some level both opinions are true. Applying that to our case we could say that the second Terutz is describing a higher reality which the scientists do not have access to, which is entirely valid at that level.

Once we say this, then we can say that the two Terutzim of the Gemara are not actually disputing each other in the classic sense, but rather describing two different levels of reality. According to the first Terutz, which is operating at the empirically observable level, the events surrounding the birth of Dina were completely miraculous, whereas according to the second Terutz which describes a higher level of reality, these events were natural and were affected by sincere Tefilah. There does remain, however, a Halachic dispute over whether one is permitted to Daven in the case of b'Vas Achas.

With this, I believe, we have b'Siyata d'Shemaya resolved our dilemma, and I submit my words to you for scrutiny and comments.

B'Kavod Rav,

Yonason Sigler