Risk of oxidation while taking hydrometer readings??

Ive searched the forum some and while i'm sure this topic has been covered, i cant easily find a thread that relates. So my apologies at the outset if this is redundant.

I'll be taking a hydrometer reading on my first batch in a couple of days. It is a 5 gallon batch which is in a 6 gallon glass carboy. My concern is, with this much head space, do i risk oxidation when i remove the bung & airlock. I understand that i need at least two consecutive identical readings to ensure fermentation has stopped. Since this might require several samples, what are my risks and, are there any procedures i can follow to reduce any risk.

Any advice is greatly appreciated.

There is a blanket of C02 over your beer and since C02 is heavier than air, there's no risk of oxidation.

Dang! Talk about fast service!

Thanks for the explanation!