How we cite our quotes: (Chapter.Paragraph)
Quote #1
Something about Anthony Jr.'s life and death inside ma had changed her in some unfixable way. She'd grown herself a big rear end and developed an unpredictable facial twitch. (2.9)
Ma's grief over her miscarriage manifests itself physically. This must be something she passes on to Dolores, who also gains weight when she goes through trauma of her own.
Quote #2
In January the hospital gave us back a new version of Ma: a smiling, twitchy woman with plucked eyebrows. (4.1)
Okay, so as we see from the previous quote, the twitch isn't new, but the eyebrows and the smile are. Ma has changed in a way that is similar to, but less dramatic than, the way Dolores will change after her own stint in a mental hospital later on.