If you've read any pregnancy books ever, you know that heartburn is a common pregnancy symptom. Progesterone is the culprit of this and a lot of other uncomfortable pregnancy symptoms. It relaxes your esophageal muscles and allows for "back-flow" of stomach acids. I have not experienced this, which according to everyone on the planet also means my baby has no hair. (That's right, heartburn = baby has hair. It makes no sense, but everyone swears it's true.)
Instead of heartburn, I get a very annoying and sometimes startling symptom. Occasionally, my esophageal muscles relax so much that they stop working for a second. This, in turn, keeps the top of my throat from noticing that saliva is a potentially lethal substance if BREATHED instead of SWALLOWED because my throat is SLEEPING. So about 9 times a day, I do that coughing/choking thing...you know, the one where you choke and can't breath and you're eyes water and, simultaneously, you're attempting to convince everyone in the room that you're fine by trying to say, "I'm fine," but what comes out is similar to what a 70-year, 4-pack-a-day smoker sounds like, which then causes you to hack even harder and louder so you do the deep, heaving breath thing because at this point it's been about 20 seconds since you've actually taken in oxygen and now everyone thinks you're hyperventilating, so you put your hands up as if to show that if you can move your arms, no one should be alarmed and everyone can resume eating their soup? You know, that kind of cough? Sure, it's not that embarrassing when you're just with your friend or significant other. But when you're on a business call and you have to stop the call for 45 seconds while the person on the other end waits for you to figure out the difference between swallowing and breathing, it's pretty much the worst feeling ever. And afterwards, you inevitably say something stupid like, "I'm going to practice breathing and talking at the same time before our next call, Phil, I swear!"
The pregnancy books don't mention all that.