Комментарий к Берешит 30:17

וישמע אלהים אל לאה AND GOD HEARKENED UNTO LEAH —for she eagerly desired and sought means to increase the number of the tribes (Genesis Rabbah 72:5).

וישמע אלוקים אל לאה, because she had used both natural means, and then, failing to succeed, relied on prayer. She herself is on record as confirming this when she said נתן אלוקים שכרי אשר נתתי שפחתי לאישי, “G’d has given me my reward for having offered my handmaid to my husband. Giving Zilpah to Yaakov was considered by her as a way of relying on natural means of having more children, seeing she had come to the conclusion that she could not have any more from her own womb.

וישמע אלוקים, G'd heard, etc. This means that Leah prayed to G'd first.