According to the American Gerbil Society, gerbils eat their young when their water source runs dry and when their pups are stillborn. Eating stillborn young is an instinctual behavior in gerbils that is performed in order to keep their nests and cages clean and sanitized.
Gerbils are considered excellent parents and are not known to harm their young. The length of pregnancy in a mother gerbil is typically between 21 and 25 days, but in certain cases pregnancy can be as long as 43 days. The average litter size is five to six pups. In most cases, healthy gerbils give birth without complications, but it is important for gerbil owners to consult with a veterinarian if their mother gerbils show signs of illness prior to giving birth to prevent serious complications.