Neutral, standard word for one's own mother or a mother in general. Slightly more formal than お母さん (okaasan), which is the usual address term.
彼女は三人の子供の母親です。
She is the mother of three children.
母親に電話をかけた。
I called my mother.
She became a mother last year.
As a mother, I put my child's safety first.
My grandmother was like a mother figure to me.