Stop doing this. Just stop it.
I don't care if your baby sleeps the whole time (though if you MUST bring your baby to a movie I paid good money to enjoy, then let's hope he/she is silent). Clearly, this is better than the alternative.
But it's an awful thing to subject the baby to.
It's loud, there are bright flashes of light, sometimes crazy music and scary sounds. Like, for their sake just find someone to watch the baby or do as we (and other reasonable and considerate people) have done...DON'T FUCKING GO TO THE PLACE UNTIL YOU CAN DO SO WITHOUT SUBJECTING EVERYONE ELSE TO YOUR CRYING BABY.
It's bad enough when it's a kid's movie (though so of them are as crazy and disturbing from a sensory overload perspective as adult movies) but for the love of gawd don't take them to movies that have yelling, gunfire, explosions and other mayhem. If you were in a park and someone started doing those things near your baby, you'd freak the fuck out. So why is it OK for you to bring them into that AND to disturb the experience of other movie-goers. ESPECIALLY parents who found a babysitter and are getting some much-needed child-free time to go watch their favorite "surely there couldn't be any kids in this R-rated movie" flick, then lo and behold here you come strolling in with your baby.
The worst, though, is when people bring babies to movies, they start crying and they don't immediately take that baby somewhere else. If you can't console the child within 20 seconds, you gotta go. Now everyone is focusing on the crying, how annoyed they are with the parent(s) and their poor decision and then they can’t focus on the movie.
It’s not out of the question to spend $50 or more to go watch a movie with another person, and if you have an age-appropriate child or two you could be looking at close to $100. THEN, there is the possible babysitter cost so that they could NOT bring a baby to the movie theater.
Nobody said to themselves “I’m going to pay all this money and be fine if someone brings a baby into the theater who then starts crying and stays in that theater”. Nobody. Ever.
So, please, stop doing it. Of course, you can still have a life after having a baby (it might take 6 months before you can do certain things again). And yes, babies on planes are just something to expect. Sometimes there's no choice but to do that. But under no circumstances is it NECESSARY that you go watch a movie...and certainly not if you have to bring a baby. Figure out a different way. Same goes for restaurants that aren't aimed at young kids (like an expensive steak place, for example). Have some respect for people who pay hard-earned money to enjoy a night out in a place that is reasonably expected to be baby-free.