Cardi B Already Hitting Gym 1 Week After Giving Birth, Doctors Weigh in

Cardi B isn't listening to critics as she faces backlash for hitting the gym a mere week after giving birth to her third child ... though, doctors tell us she might want to heed the warnings.

Here's the skinny ... the rapper took to Instagram Sunday, documenting herself on the StairMaster a little over a week after welcoming her third baby with Offset. This sparked a big reaction online ... with fans expressing concern for her well-being, while others slammed her for succumbing to "snap back" pressure.

Cardi made it clear she was tuning out the peanut gallery ... returning to the gym again Monday, pointing out she's only doing 30-minute sessions, and taking it slow. As Cardi put it, she's using cardio to help prevent postpartum depression, noting it's her third time going through this experience.

We spoke to a handful of OBGYNs, each offering up different opinions on the issue.

One doctor said most docs in their profession would recommend against going to the gym right away ... clarifying, however, that it's a case-by-case basis. Per the medical professional, if a woman gives birth naturally and has a smooth delivery, a doctor may sign off on the new mom easing back into light activity ... like walking.

However, the doc urged expectant mothers to consult their personal OBGYNs before doing anything strenuous.

Another doctor expressed a slightly different sentiment ... explaining they wouldn't personally clear a patient for exercise until 2 or 3 weeks postpartum. But, they know others who might clear a patient at the 1-week mark.

A third OBGYN urged fans not to do something just because a celebrity is doing it ... again, advising mothers-to-be to consult medical professionals first.

As for why the doctors voiced concern over Cardi's decision ... many said there were risks to getting back at it, as bodies need time to heal after a birth. Some possible side effects of rushing into working out postpartum include a hernia, strained muscles, a pelvic prolapse, and bladder problems, among other issues.

The warning is even more severe for women who've had C-sections ... as an infection at the incision site, loss in abdominal strength, scar trauma, and more could all arise if they begin working out before at least 6 weeks have passed.