I would commend your friend's wife for choosing the right priorities. Family is the most important thing in the world. 7 months is a really short time for maternity leave.

How can someone "exploit maternity"? Maternity is not the same thing as being sick. Being sick is a transient personal thing while parenthood is a process that lasts through a lifetime.

People need sleep and eating. People are not machines. The fact that people are not required to work 24 hours a day recognizes this. People also need an occasional time off. This is recognized as well.

Family is a similar natural need, but with different temporal cycles. Any workplace that does not recognize the allowances required for family is not really in it for the long term.

Any coworkers that begrudge a maternity or paternity leave are themselves at fault, not the parent.