My rat is pregnant. How do I know if she's overdue or in labor?

The gestation period for a rat is normally 22 days, but can vary from 21 to 23 (and rarely to 26). A postpartum pregnancy will last 28 days. Two weeks into the pregnancy the mother's abdomen will usually start expanding, but not always.

As the birth approaches, you may be able to see the pups moving inside her, or feel them if you gently feel her abdomen. Her mammary glands will also start to enlarge two weeks into the pregnancy.

The birth process normally takes about an hour or two. In general, the mother rat will deliver a new pup every 5-10 minutes. In rats, the average litter size is 6-13 pups. The first sign is a bloody discharge from the vagina. Next, the contractions will cause her to stretch out while her sides suck in, in a most amazing way. Once the babies start arriving, the mother will sit up and help deliver them with her hands and teeth. Then she will clean off the birth sac and lick the newborn. The mother will usually eat each placenta and the umbilical cord. During this process a healthy baby will wiggle and squeak, which inhibits its mother from eating it too. However, if a baby is weak or dead, this inhibition may not occur.

Hope this helps. Best wishes.