Quote from mama.RN
Sounds like possible wrongful termination.....google for more info and it's probably worth consulting an attorney.....this is what I found by googling "wrongful termination and pregnancy":
"Wrongful Termination Laws: Discrimination-- Under federal law, it is illegal for employers to fire an employee because of the employee's race, gender, national origin, disability, religion or age (so long as the employee is at least 40 years old). In addition to these "protected classes," federal law also makes it illegal for employers to fire an employee because she is pregnant or has a medical condition that is related to her pregnancy or childbirth."
Unfortunately, she CAN legally be fired if the employer can prove they'd fire a non-pregnant person for the same reason. No, she can't be fired because she is pregnant. However, the employer could argue that her excessive absence (beyond FMLA) is an undue hardship for the company, especially if that's how they dealt with other non-pregnant employees who took too much sick time off. Her excessive absence--not the pregnancy--would then be the reason.
Fair? Not always. Reality? Yes.
OP: I agree that it may be worth talking to a lawyer to see what your options are, especially since you got the letter right after FMLA ended. However, don't expect your pregnancy to guarantee that you'll get your job back, or that it'd be insurance for the next job that you get before you give birth. Pregnancy is not bullet-proof job security.
I'm sorry if it's not what you wanted to hear....and lest you think I'm unsympathetic, I'm in my third trimester as I type this. I've made it a point to stay on top of what this means to me at work and what my options are/would be after the birth or if problems should arise beforehand. I've been fortunate so far in both work and pregnancy, but that can easily change. So I do understand your frustrations and fears.
Best of luck with the remainder of your pregnancy. Ultimately the health of you and your little one is far more important.