Берешит 16:4 Комментарий: Rashi, Kitzur Ba'al HaTurim, Radak & The Midrash

ויבא אל הגר ותהר AND HE CAME UNTO HAGAR AND SHE CONCEIVED from the first union (Genesis Rabbah 45:4).

"She conceived ב''פ" (in the second month) in the portion. From here, there is a hint to Rashi's commentary that the evil eye affected her and caused her to miscarry, and then she became pregnant again."

ויבא ... ותקל גבירתה, she thought that now that it was clear that Avram's seed would be from her she would become the top ranking wife of Avram. As a result, she refused to carry out instructions given to her by Sarai.

ותקל גברתה בעיניה HER MISTRESS WAS SLIGHTED IN HER EYES — She said, “As regards this woman Sarai, her conduct in private can certainly not be like that in public: she pretends to be a righteous woman, but she cannot really be righteous since all these years she has not been privileged to have children, whilst I have had that blessing from the first union” (Genesis Rabbah 45:4).