If she is truly checking in on the baby, she should call (ie. make the effort but no need to tell her that). You don't always check your text messages and can't guarantee an immediate response by text.
Set this as a boundary, then no longer do you need respond to texts. If she calls, she needs to stay on topic. You stay polite, friendly, but no R discussion. You end the call fisrt because you are busy and have more important things to do than chit chat with her.
Spellfire aka Mike
"Women do not like controlling men. They respect and are attracted to men who control themselves. They ultimately are repelled by men who allow themselves to be controlled." -S&A