Pregnant rat mystery

My female that had babies on the 1st looks pregnant. Only issue is she hasn't been with a male since before she had the babies. http://img.tapatalk.com/d/12/12/19/apy2upu8.jpg

Sent from my Droid RAZR M using Tapatalk 2

If she was with the males even a day before she gave birth, she could easily be impregnated again by that same male, and yes, she looks pregnant.
If the future it's a good idea to separate the male and female after you are sure the female is pregnant so you can give her a break between litters.

A lot of times, if I don't pull the female in time she will be giving birth in the breeding tubs and the male will be humping her at the same time! Then I pull her and her babies, put them in a birthing tub and while she is raising them, she gives birth to ANOTHER litter. I hate that because it wears out the females.

Sent from my Galaxy Nexus using Xparent Red Tapatalk 2

She wasn't with a male for about a week b4 she had the babies.

Sent from my Droid RAZR M using Tapatalk 2

I just ha a female look like this too. It went away and now she looks normal. No babies. It was a white rat also did she have a big litter??? Mine was 16 before maybe that ha something tondo w it

She had 12. She's looked pregnant for about a week just keeps getting bigger.

Sent from my Droid RAZR M using Tapatalk 2

Apparently, rats can retain sperm.
There are some first hand accounts if you google it.

Female rats can retain sperm for a certain number of days, but I agree that if the male isn't removed before birth she will automatically go back into heat within the first 24hrs. of giving birth to her litter.