The Villain’s Mother The Villain and the Cannon Fodder’s Mother The Male Lead’s Villainess Stepmother Transmigration: Raising the Child of the Male Lead Boss The CEO’s Villainess Childhood Friend She Become Sweet and Cuddly My Wife Spoils Me Too Much
Go take a look at the works translated by FuyuNeko. They have several novels about women transmigrating into the bodies of young mothers (and therefore suddenly finding themselves mothers).
My apologies but the first thought that came to my lewd mind is instant milf... Anyway, I recommend From Maid to Mother
Maybe something like: Wagamama Onna From Maid to Mother While Killing Slimes for 300 Years, I Became the MAX Level Unknowingly