Being pregnant is different for every woman. Some women enjoy it, do well, and have an easy time. Others are the opposite, suffering from countless nightmare scenarios that make it an unbearable ordeal. The spectrum is so wide, there's no possible way to delineate every single outcome. What's worse is that each pregnancy is different, so women can have a fantastic pregnancy, but then a nightmare one the next time, and vice versa. Because of its completely unpredictable nature, it can be difficult for others to understand and properly compensate for a pregnant coworker.
Possibly the worst place to work while pregnant is in retail.
Retailers don't care if you have morning sickness, gestational diabetes, or anemia. They have policies in place to protect themselves from lawsuits, and can't legally terminate you for being pregnant. That's the business. The people you work with, however, aren't the business. Their reactions don't always fall in line with company policy. A lot of the time, they're more interested in their bottom line than anything else, and as far as they're concerned a pregnancy is only going to get in the way of that. Pregnancy isn't always something that they see as deserving sympathy or concern until you actually start showing. Once that happens, it's like a switch is flipped and suddenly you're treated like an invalid who couldn't possibly be able to help a customer without risking giving birth in an aisle.
I have two children, and was working retail while pregnant with both of them. With my son, my only issue was being hungry all the time. It was bad enough that my coworkers were hiding snacks behind every single workstation's monitor to bribe me with so that I wouldn't start chewing on people's arms. They were wonderfully supportive and helpful, and weren't afraid to scold me when I did things I shouldn't out of habit. When it came time to go on maternity leave, they threw me a party and gave me a present so I wouldn't "get bored" while I was gone.
The second time around wasn't quite as simple. My second pregnancy started off with intense pain and me not even knowing I was pregnant until I went to a doctor. I was diagnosed and then immediately sent off for an ultrasound to find out if the pregnancy was ectopic. Imagine for a moment you learn you're going to have a child, and then learn within the same breath you might need an abortion in order to save your own life. Setting aside the moral issues surrounding the topic of abortion, just picture for a moment what it would be like getting sucker punched twice in a row like that.
It turned out to not be the case, but only barely. Based off the ultrasound, the egg had exited the tube but implanted within a half-inch of that exit, which was why I was in so much pain. Things progressed steadily downhill from there. As my pregnancy progressed, I was extremely ill. For the first three months I ate next to nothing and lost significant weight because my nausea was so severe. I became anemic and both faint and incredibly weak. The pressure on the left side of my body increased as my daughter grew, and I rapidly developed varicose veins in my left leg. Everything on my left side was continually being shoved around and crushed with each growth spurt. It was very close to a nightmare. If there is anything I can be thankful for, however, it was that I was free from the worst complications. I did not end up on mandatory bed rest, nor did I suffer a miscarriage.
I mention all of this because even as I was going through this horror I was still going to work. The nature of retail is that it's rare for the same people to work in the same place for more than a few years. Most of the people I'd worked with while pregnant with my son were gone for various reasons. I'd also earned a promotion during the years between pregnancies, and so had more responsibilities. While my coworkers were sympathetic to how very obviously unwell I was, not all of them were sincere in that sympathy. I will never know if it was done out of malice or spite, if those who were falsely sympathetic somehow thought I was merely faking my malaise, or if they simply did not care about my condition unless it made a direct impact on their paychecks. What I do know is that many of the very people who should have been helping me were standing back, watching, as I struggled to perform the simplest of tasks. Like stand up. Their behavior meant that, at a time I was at my weakest, the demands made of me were only increasing.
If I could make any kind of recommendation to women working while pregnant, it would be to put yourself first. Don't let your workplace or your coworkers tell you what you should be able to do, and if you need help, don't just ask. Take it. Those anti-discriminatory company policies exist for a reason. Use them! As for those who focus on the company more than the employees, if you think a woman can't do the job just because she's pregnant, maybe you should stop for a moment and go talk to your own closest female relative with children. Your mother, sister, aunt, cousin... You get the idea. Ask her what it was like to be pregnant and try to keep up with her responsibilities.
The answers might enlighten you.