How Many Months Are Rats Pregnant?
WouterFemale rats usually conceive between six and ten weeks old, and male rats are sexually mature between eight and twelve weeks old. For this reason, male and female rats should be housed separately. The gestation period is typically 21 to 23 days. A pregnant female rat is easy to spot, since she will start making a nest around two weeks old. Tissue paper is a great choice for nesting material.
When a rat becomes pregnant, her abdomen may start to swell up. The second and third weeks are particularly important because the uterus expands and sometimes moves. The rat may also develop an increased bloody discharge from the vulva, a sign of labor. She may also feel and see the newborns moving in her abdomen. The lower abdomen will also become significantly rounder.
While a rat can be pregnant for as many as four months, a female should be separated from her litter at five weeks. If the doe is not separated from her litter, she is likely to become overweight and may develop eclampsia, a disease characterized by rapid growth in pregnant rats. A healthy rat weighs about three hundred to four hundred grams.
While female rats can be bred at any age, it is better to wait until they are at least nine months old to avoid endangering the mother. Males can mate with females as young as five weeks old and still produce litters.
