I remember I was around 38 weeks pregnant when the Tutankhamun exhibit came to Dallas. I was really excited-- in high school, I'd had great plans to be an Egyptologist, so that was right up my alley. I thought I'd drive into town, have a nice time walking around and seeing the artifacts, having a great time... nope. I was pretty fatigued. I was 7 months pregnant and drove 600 miles to go camping and was walking a few miles every day, no problem--- but at almost 9 months pregnant, I was just a homebody, and not even Tutankhamun was enough to lure me from my nest.
DS1, I started having a stomachache around 7 pm. It turned into contractions around 9 pm. We left for the birth center around 11 pm. We arrived around 1 pm. I labored until about 5 am-- which is when DS1 was born.
DS2, I woke up with a stomachache, and I realized it was the beginnings of contractions. I called DH to come back from work around 10 am. We left for the birth center around 11 am. We arrived at 1 pm. DS2 was born about 15 minutes later. I still thought I had hours left to go, and didn't give my body permission--- but when the midwife explained that I had arrived already fully dilated, I relaxed enough to give birth.
Generally, labor is going to be a process that goes through stages. Your body and the baby's body are working together, and it's not always gentle.
But out of your readers, for every woman who says, "Oh, yeah, I know someone who popped out a baby in 5 minutes!" there's going to be a thousand women who say, "What planet is that woman from? I was in active labor for (5) (10) (20) hours, and then spent another x time pushing! And I definitely wasn't in the mood to be thinking about sitting through a play!"
So, when you're writing your scene--- you might keep that skepticism in mind when you fill in some of your details.
In general, any kind of medical emergency is going to be minimized. There'll be an effort to get the person safely out of the theater itself elsewhere with a minimal impact on other people. When you're in a situation where you have to clear a theater, it can lead to other people getting injured in the confusion. (For example,
someone needed a defibrillator at a Hamilton performance in San Franscisco-- it resulted in an alarm, which led to a broken leg and two other injuries because people thought it was a shooter.)
At best, putting everything on halt will just annoy the rest of the audience. (
Someone lost consciousness during a performance of Henry IV. The play was halted while crewmembers with medical training tried to help. Paramedics arrived. The person went home with friends. But it resulted in a 20-minute delay, which annoyed the rest of the audience, some of which began to leave. “God has decided this play needed a second intermission! … Get back here or find this sword and many a dagger placed neatly in the tires of your carriage!” Hanks shouted.)
So the best thing to do is to be discreet, and get yourself out ASAP if you're able to-- otherwise, you need to rely on others around you to lend a hand. (
Someone was having a stroke in a movie theater. An off-duty paramedic carried her down the stairs, gave her a stroke test, and called 911.)
Here's a
blog post by a stage manager who has to make the decision on how much an individual's medical emergency will be allowed to affect others in the theatre.
Here's a
thread by Broadway lovers who talk about different medical emergencies they've encountered at various performances-- incontinence, strokes, death, etc.
Here's a
handbook of stage manager duties.
Here's a
checklist for running a crowded event safely and planning for emergencies.