Dear Neha,
What is the context of your question? You could have given a little elaborate post?
To terminate an employee, whether pregnant or not, there have to be compelling reasons. Pregnancy is not a shield that protects the woman employee from any type of misconduct. If the woman employee has committed misconduct then these need to be investigated and if found blameworthy, then your company may go ahead with the punitive action. However, make sure that the punishment commensurates the misconduct.
While taking action, follow the principles of natural justice strictly. Since the woman employee is pregnant, she is entitled to the maternity benefits. These are independent of the punishment and she should not be deprived of the benefits.
Thanks,
Dinesh Divekar