Kommentar zu Schemuel II 3:5

By Egloh This refers to Michal⁷The daughter of Shaul. who was cherished by him. Similarly it says "If you had not plowed with my calf" (Shoftim 14, 18).⁸עגלה, “calf” is used in reference to a cherished wife just as a calf is cherished by it’s owner (See Sanhedrin 21a). [But] it is written, "And Michal, the daughter of Shaul had no child until the day of her death" (Below, 6, 23) she didn't have one until the day of her death⁹At which time she died in childbirth (ibid).?¹⁰That verse implies that Michal had no children up to the time of her death, but our verse states that Egloh, i.e. Michal gave birth to Yisrom. From that incident¹¹Dovid rejoiced excessively when the Ark was returned from captivity. Michal rebuked Dovid for what seemed to her to be behavior beneath his dignity. This was not the case and she was punished for the unwarranted shaming of Dovid. (ibid). and on [she had no children], but prior to that incident she did have [children].