Um.. She looked insanely too young to be breeding... Get your boy another boy to be friends with(AFTER quarantine...) and he'll be much happier.

And rats are very prone to respiratory problems, since they naturally carry a bacteria(mycoplasma pulmonis) that reduces their immune system so they can't fight some infections off.

Did you quarantine her? 30 days MINIMUM in a separate location, otherwise your boy has the potential to get VERY sick too. Last year, I stupidly brought home 3 babies from Petsmart.. I know you're thinking... Petsmart is trustworthy, right? No... I had 8 rats die within 2 weeks from a streptococcol based pneumonia that was pretty resistant to everything. So yeah, I quarantine for about 3 months now, regardless.

Did you know her genetics as well? She's a high white marked rat, and if you bought her from a pet store, she is most likely carrying genes that pass onto her babies that create megacolon. Megacolon creates problems with the muscles in the digestive tract to where they don't contract like they should. So the babies get impacted, can't absorb any nutrition and slowly(or quickly) starve to death.

It is not a fun thing to go through, and high white breedings should ideally be left to the professionals who know EXACTLY the genetics of their animals.

How long had you had this rat? If you had just picked her up from the pet store a few days ago, see how your male does in a week or two(incubation period for viral/bacterial illnesses) because he very likely could come down with something.