In seven months Leah bore her children, and within seven years eleven sons and one daughter were born to Jacob. And all of them were born, and their mates [destined spouses] were born with them, except for Joseph, whose mate was not born with him, for Asenath the daughter of Dinah was fitting to be his wife; and except for Dinah, whose mate was not born with her. He [Jacob] said, "This girl is judgment and justice [din u-mishpat]," and therefore he called her name Dinah.
Leah's Swift Births and Why Dinah Was Named for Judgment
Yalkut Shimoni on Torah 125:6
מִשֶּׁבַע חֳדָשִׁים יָלְדָה לֵאָה אֶת בָּנֶיהָ, וּלְשֶׁבַע שָׁנִים נוֹלְדוּ לְיַעֲקֹב אַחַד עָשָׂר בָּנִים, וּבַת אַחַת, וְכֻלָּן נוֹלְדוּ וְנוֹלְדוּ זִוּוּגָן עִמָּם, חוּץ מִיּוֹסֵף שֶׁלֹּא נוֹלַד זִוּוּגוֹ עִמּוֹ, שֶׁהָיְתָה אָסְנַת בַּת דִּינָה רְאוּיָה לוֹ לְאִשָּׁה, וְחוּץ מִדִּינָה שֶׁלֹּא נוֹלַד זִווּגָהּ עִמָּהּ, אָמַר, הַיַּלְדָה הַזֹּאת דִּין וּמִשְׁפָּט, עַל כֵּן קָרָא שְׁמָהּ דִּינָה.