How risky is it to fire a pregnant employee having attendance problems?

Q. An employee has been with us for less than a year, so she isn’t yet eligible for FMLA leave. Last month she missed five days because her child had a high fever. She used available PTO for the time off. Last week, she was no-call/no-show for three days. She told the supervisor she had been hospitalized because of pregnancy complications and didn’t have access to a phone and was sedated. She provided a doctor’s note that released her to return to work, but stated that she may need to be put on bed rest. The supervisor would like to terminate her because we can’t afford to continue employing someone so unreliable. Can we do this?