I'm studying medical data. My case have Preterm Premature Rupture of Membranes and benefit of amniocentesis for detection of infection. My controls have only PPROM.

I've matched with month and year but I realize that at the period of time I'm doing my study there is no statistical biais related to the period (because the medical procedures are the same, the patients are the same..).

So is there any sens to match in a case-control study with a factor which is not confounding? or should I change my matching? (which is quite complicated...)

Thanks a lot,