Getting female rats from a pet store already pregnant isn't always the "deal" it appears to be as you'll see a lot more of this sort of thing. A healthy female rat delivers with almost no blood left on the bedding when she's done. A lot of the pet store females get pregnant accidentally in a large mixed feeder tank and aren't in good physical shape to start with or are very young to breed. Then they have to compete for food while pregnant with the other rats and then in your case get taken home almost ready to pop. It's pretty much a recipe for disaster so count yourself lucky any of the babies made it.

Much better to buy young females around 4 or 5 months old that have been seperated by sex, fatten them up a bit and get them settled in - then introduce them to your male rat. A healthy female makes for a healthy, large litter and if your breeding for feeders that's your goal.

Just to give you some idea. This pic is of a female rat giving birth for the first time...note the lack of any mess or afterbirth/blood laying around (she went on to have a total of 12 pinks).....


This is the same litter after delivery. All I did was reach in and remove the female before I took this pic. This is the area she had just given birth in. She like most females later moved her babies across the enclosure to a nest she constructed.