Beyonce Baby Drama -- Breastfeeding Moms Plotting to Sue Hospital

Lactation and retaliation ... TMZ has learned a bunch of new moms are passionately discussing BOTH topics at the hospital where Beyonce just gave birth.

Sources at Lenox Hill Hospital in NYC tell TMZ ... the mothers have been gathering at a breastfeeding class at the hospital ... and in between latching techniques, they've been griping about the way they've been treated during the celebrity lockdown.

We're told the mothers feel they've been "neglected" by hospital staff ... and now they're discussing the possibility of filing a lawsuit against LHH.

According to NYDailyNews.com, Bey and Jay-Z dropped $1.3 mil to seal off a private wing of the hospital ... with private security roaming all over the place.

Our sources say several mothers have been seen arguing with Bey's security people ... accusing the hired muscle of being "extremely rude."

Still, we're told the mothers are not mad at Bey and Jay -- directing the blame solely at the people who run the hospital.

One source tells us, "Someone at the hospital should be protecting us patients."