ויתרוצצו. עַ"כָּ הַמִּקְרָא הַזֶּה אוֹמֵר דָּרְשֵׁנִי, שֶׁסָּתַם מַה הִיא רְצִיצָה זוֹ וְכָתַב אִם כֵּן לָמָּה זֶּה אָנֹכִי? רַבּוֹתֵינוּ דְּרָשׁוּהוּ לְשׁוֹן רִיצָה; כְּשֶׁהָיְתָה עוֹבֶרֶת עַל פִּתְחֵי תּוֹרָה שֶׁל שֵׁם וָעֵבֶר יַעֲקֹב רָץ וּמְפַרְכֵּס לָצֵאת, עוֹבֶרֶת עַל פֶּתַח עֲבוֹדַת אֱלִילִים, עֵשָׂו מְפַרְכֵּס לָצֵאת. דָּבָר אַחֵר מִתְרוֹצְצִים זֶה עִם זֶה וּמְרִיבִים בְּנַחֲלַת שְׁנֵי עוֹלָמוֹת. ויתרצצו AND [THE CHILDREN] STRUGGLED — You must admit that this verse calls for a Midrashic interpretation since it leaves unexplained what this struggling was about and it states that she exclaimed “If it be so, wherefore did I desire this” (i.e. she asked whether this was the normal course of child-bearing, feeling that something extraordinary was happening). Our Rabbis explain that the word ויתרוצצו has the meaning of running, moving quickly: whenever she passed by the doors of the Torah (i. e. the Schools of Shem and Eber) Jacob moved convulsively in his efforts to come to birth, but whenever she passed by the gate of a pagan temple Esau moved convulsively in his efforts to come to birth (Genesis Rabbah 63:6). Another explanation is: they struggled with one another and quarrelled as to how they should divide the two worlds as their inheritance (Yalkut Shimoni on Torah 111:2).
ותאמר אם כן. גָּדוֹל צַעַר הָעִבּוּר. ותאמר אם כן means AND SHE SAID, “IF the pain of pregnancy be so great,
למה זה אנכי. מִתְאַוָּה וּמִתְפַּלֶּלֶת עַל הֵרָיוֹן: למה זה אנכי WHY IS IT that I longed and prayed to become pregnant?” (Genesis Rabbah 63:6).
ותלך לדרוש. לְבֵית מִדְרָשׁוֹ שֶׁל שֵׁם: ותלך לדרש AND SHE WENT TO ENQUIRE at the school of Shem (Genesis Rabbah 63:6).
לדרוש את ה'. שֶׁיַּגִּיד לָהּ מַה תְּהֵא בְּסוֹפָהּ: 'לדרש את ה, TO ENQUIRE OF THE LORD, that He might tell her what would happen to her at the end.