The pregnancies for each and every one of Yaakov's children were extraordinarily short, and were thus able to fit within a seven year time span. Similarly, Yaakov's children reached physical and sexual maturity at supernaturally early ages, and this accounts for the very young ages of Shimon and Levi and Yehuda's descendants when they sired offspring in the subsequent stories.
Fitting in all of the births – Seder Olam Rabbah and Pirkei DeRabbi Eliezer speak of twelve consecutive seven month pregnancies which add up to the second set of seven years Yaakov worked for Lavan.
2 The Tosafists
3 take this a step further, arguing that the pregnancies themselves lasted only a little more than six months as there was a need for interim days of ritual impurity after each birth.
4 No overlap or twins – This position takes the order in the text extremely literally and thus assumes that each pregnancy was completed before the next one began.
5 Moreover, according to Pirkei DeRabbi Eliezer, each of Yaakov's sons
6 had a twin sister born with them who was to be their future wife, thus leaving no room to suggest that any of the Tribes were twins to each other. The alternative solution that there was a set of twins is proposed by
R. Yosef Bekhor Shor and
Radak.
7 Shimon and Levi – Seder Olam Rabbah and Bereshit Rabbah posit that Yaakov spent two years in transit on his way back from Lavan's home. This allows the Albeck version of Bereshit Rabbah to arrive at an age of 13 for Shimon at the time of the incident in Shekhem, and to justify the description of him as an "אִישׁ" in Bereshit 34:25.
8 The Vilna edition of Bereshit Rabbah, as well as Rashi and Seikhel Tov propose that Levi, too, had reached the age of maturity at the time of this event.
9 Yehuda's offspring – Seder Olam Rabbah and Bereshit Rabbah assume that the events of Bereshit 38 are recorded in chronological order, and that Yehuda's first marriage took place only after the sale of Yosef.
10 This forces them to fit three generations of births in Yehuda's family into a window of a mere 22 years, which, in turn compels them to postulate that these generations procreated at the age of seven.
11 Chizkuni provides a detailed chronological reconstruction of the sequence of events.
"מָלְאוּ יָמָי" and "מַלֵּא שְׁבֻעַ זֹאת" – According to Rashi and Chizkuni, "מָלְאוּ יָמָי" indicates that Yaakov had completed his first seven years of service before marrying Leah.
12 Bereshit Rabbah, Pirkei DeRabbi Eliezer, and Rashi,
13 thus explain that "מַלֵּא שְׁבֻעַ זֹאת" refers to the seven days of post-nuptial festivities, as the years of work were already complete.
14 "וַתַּעֲמֹד מִלֶּדֶת" – According to this approach, there was an interim period of over two years in which Leah did not become pregnant.
Births of Yosef and Dinah – This reconstruction maintains that Dinah and Yosef were born seven months apart toward the end of Yaakov's fourteenth year in Lavan's house. Chizkuni notes that "וַיְהִי כַּאֲשֶׁר יָלְדָה רָחֵל אֶת יוֹסֵף" coincided exactly with the completion of the second set of seven years.
Crux of the position – The approach adopted by the Midrashim adheres to a very literal chronological order of all of the verses and chapters, and explains away all questions by assuming that the events were supernatural or miraculous. Or, as Ralbag describes the Midrashic method, "וזה כולו היה ממנהגם, להפליג בחוזק ההשגחה האלהית ולפרסם עניינה אל ההמון".
The Torah favors thematic order over chronological order15 and therefore presents the pregnancies and births as consecutive, even though they needed to overlap with each other to fit into the seven year time frame. Similarly, positing achronology resolves the difficulties in the later stories of Sefer Bereshit, with the story of Shimon and Levi in Shekhem transpiring only many years after Yaakov returned from Lavan's home, and Yehuda's first marriage occurring several years before the sale of Yosef.
Overlap and twins – These commentators posit a number of possible variations as to how the pregnancies of Yaakov's wives overlapped. According to Demetrius and Lekach Tov,
16 Bilhah's pregnancies overlapped with Leah's first four pregnancies
17 and Zilpah's pregnancies overlapped with Leah's later three pregnancies, while Ibn Ezra and Sforno suggest that it was Bilhah's and Zilpah's pregnancies which overlapped.
18 Ibn Ezra also raises the possibilities that Zevulun and Dinah were twins or that Dinah was born much later.
19 Fitting in all of the births – The overlap in pregnancies enabled twelve full term births during the course of Yaakov's second seven year work stint.
Shimon and Levi – Demetrius and Ibn Ezra suggest that Yaakov lived in Shekhem for several years before the rape and massacre took place,
20 allowing for a much older Shimon and Levi.
21 Lekach Tov, on the other hand, maintains that Shimon and Levi were just thirteen to fourteen years old.
22 Yehuda's offspring – Both Lekach Tov and Ibn Ezra suggest that Yehuda's initial marriage in Bereshit 38 is recorded out of chronological order, and that it really occurred before the sale of Yosef. The extra years thereby gained allow for the possibility that Yehuda and his descendants each sired children at the more plausible age of thirteen.
"מָלְאוּ יָמָי" and "מַלֵּא שְׁבֻעַ זֹאת" – These commentators do not explicitly relate to the meaning of Yaakov's words "מָלְאוּ יָמָי", but they assume that Yaakov had already finished his first seven years of labor before marrying Leah. Thus, Ibn Ezra explains that "מַלֵּא שְׁבֻעַ זֹאת" refers to the seven days of rejoicing after the wedding and not the years of service.
"וַתַּעֲמֹד מִלֶּדֶת" – As this position does not posit any premature births,
23 Leah must have given birth to seven children in the same number of years. If she became pregnant shortly after each birth, there is room for her to have ceased conceiving for about one year after Yehuda's birth.
24 Births of Yosef and Dinah – According to Demetrius and Lekach Tov, both Dinah and Yosef were born in the final year
25 of Yaakov's second seven year term of service to Lavan. Ibn Ezra, though, notes the possibility that Dinah was born only afterwards.
Crux of the position – This approach attempts to solve difficulties in the narrative by positing relatively minor rearrangements of the order of the events, both within the same story as well as between stories. It avoids supernatural explanations.
The births of Yaakov's first twelve children took place over a period of almost fourteen years, rather than seven. This approach subdivides over whether it is the starting line or end point which needs to be adjusted to gain the additional years.
Yaakov Married Earlier
Yaakov married Leah immediately upon starting working for Lavan, and thus Yaakov's first twelve children were born over the course of thirteen years. As a result, Shimon and Levi were about twenty at the time of the incident in Shekhem, and there is additional time for Yehuda's descendants to sire their own offspring before descending to Egypt.
"מָלְאוּ יָמָי" and "מַלֵּא שְׁבֻעַ זֹאת" – Ralbag explains that Yaakov requested that he be allowed to marry before beginning his first seven year stint,
26 and Lavan acquiesced.
27 "מָלְאוּ יָמָי", according to this, means that Yaakov was already an old man.
28 Consequently, this position could have explained that "מַלֵּא שְׁבֻעַ זֹאת" refers to the completion of the first seven years of labor.
29 However Ralbag opts to render it as referring to the seven days of nuptial festivities.
Fitting in all of the births – Ralbag notes that according to his approach, there is no longer a problem, as one can easily fit twelve consecutive births
30 into an expanded fourteen year time frame.
Shimon and Levi – According to Ralbag's timeline, Shimon and Levi were approximately twenty
31 when they took revenge against the city of Shekhem.
32 Yehuda's offspring – Ralbag states that this is the main motivation for his approach.
33 By pushing the births of Yaakov's first children back by seven years, Yehuda can be fifty years old upon his arrival in Egypt, and there is more time for multiple generations of his descendants to have had their own children.
34 "וַתַּעֲמֹד מִלֶּדֶת" – According to this approach, this interim period in which Leah did not give birth could have lasted as much as a few years.
Births of Yosef and Dinah – Ralbag says that Yosef's birth coincided with the completion of Yaakov's second seven year term of service.
35 Crux of the position – Ralbag adopts a more rationalist position, according to which babies were carried to full term and physical maturity was reached at ages which correlate with modern experience.
36 In order to do so, he significantly challenges the simple reading of a number of texts and posits that selected verses are out of order.
Yosef Born Later
Yosef was born only after the completion of Yaakov's first fourteen years working for Lavan, and the twelve children were born over a span of up to twelve years. The incident with Shekhem happened only much later when Shimon and Levi were already twenty years old.
Birth of Yosef – According to both Jubilees and R. D"Z Hoffmann, Yosef was born only some time after Yaakov had already completed both of his seven year stints. R. D"Z Hoffmann suggests that after finishing his work for Lavan, Yaakov worked for other employers, and only at the end of this unmentioned period was Yosef born.
37 Thus, Yaakov's request for leave (and then for a change in the terms of his salary) was unconnected to the completion of his fourteen years which had occurred much earlier.
38 Birth of Dinah – Jubilees says that Dinah was born three months after Yosef. R. D"Z Hoffmann, on the other hand, suggests that she may not have been born until after Yaakov returned to Israel, and that this would account for her absence in Bereshit 32:23 and her being mentioned separately in Bereshit 46:15.
39 Fitting in all of the births – This more elastic time frame affords ample time for all of the pregnancies,
40 and even provides enough of a break between Leah's pregnancies to enable her to nurse each of her children for several months
41 before becoming pregnant again.
42 Shimon and Levi – According to both Jubilees and R. D"Z Hoffman several years elapsed between leaving Lavan's home and the incident in Shekhem. Jubilees, thus, asserts that Shimon and Levi were over twenty
43 when they killed the males of Shekhem
44 and Dinah was twelve.
45 Yehuda's offspring – According to R. D"Z Hoffmann, Yaakov's extra years of employ in Charan allow Yehuda to be old enough at the time of the descent to Egypt to have sired multiple generations of offspring.
46 According to Jubilees, Peretz was only one year old when they descended to Egypt, and Chetzron and Chamul were not alive to be counted among the seventy souls who arrived.
47 "מָלְאוּ יָמָי" and "מַלֵּא שְׁבֻעַ זֹאת" – Jubilees and R. D"Z Hoffmann both understand "מָלְאוּ יָמָי" to mean that Yaakov had completed his first seven years of work before marrying Leah. Consequently, they both interpret "מַלֵּא שְׁבֻעַ זֹאת" to refer to the seven days of nuptial celebration.
48 "וַתַּעֲמֹד מִלֶּדֶת" – Jubilees has a three year hiatus between the births of Yehuda and Yissachar, while R. D"Z Hoffmann posits only a single year interruption.
49 