Normal cat birth

The stages of birth  

In pregnancy, the kittens are spaced along each horn of the uterus. Each kitten is contained within its own membranes and has its own placenta through which it derives nourishment. The uterus may be considered as a muscular, sausage-shaped bag, capable of contracting both around its diameter and along its length. To help in its passage, each kitten is contained within a fairly tough double-layered bag of membranes, which are filled with slippery fluid in which the fetus floats. This serves as both protection and lubrication, and provides a distending, stretching and dilating force when the uterus relaxes in front of it and contracts behind it during the course of birth.

Birth (parturition) is generally described in three stages, although in the cat the second and third stages are repeated with each kitten and the third stage is brief and nearly continuous with the second.

The first stage

This is essentially the stage of relaxation of the cervix and vagina and the start of contraction of the uterus. Uterine contractions must always be interrupted by periods of relaxation, otherwise the blood supply to the kitten would be cut off. The pelvic muscles slacken and the perineum (the area between the anus and vulva) becomes looser and longer. Uterine contractions are not yet observable as straining, although movement of the kittens may be felt through the abdominal wall. There is little else to see at this stage except repeated visits to the prospective kittening bed, and in the dependent type of cat, an apparent desire for reassurance from the owner. Some scratching up and bed-making occurs, and panting may be seen as a late first stage feature. Vaginal discharge is rarely seen and is usually licked away promptly by the cat. In the cat kittening for the first time, the first stage can be very prolonged, even lasting up to 36 hours without being abnormal.

The second and third stages of birth

After the relaxation of the first stage, the uterine contractions become stronger and more frequent and drive the first kitten, contained within its membranes, towards and into the pelvic opening. As the first kitten enters the pelvis, the outer layer of the membranes appears briefly at the vulva as the ‘water bag’, which bursts and sheds some fluid which is usually cleared up by the cat. The inner layer passes into the pelvis and retains some of the fluid which acts as a continuing lubricant to assist the passage of the kitten.

The cat pushes to help the kitten through the pelvis. This is usually the point at which the owner can see that the cat is actually straining. Normally, delivery of a kitten from the beginning of the second stage may take from five to 30 minutes. Once the head is out, one or two more strains should complete the passage of the kitten.

This is essentially the stage of relaxation of the cervix and vagina and the start of contraction of the uterus. Uterine contractions must always be interrupted by periods of relaxation, otherwise the blood supply to the kitten would be cut off. The pelvic muscles slacken and the perineum (the area between the anus and vulva) becomes looser and longer. Uterine contractions are not yet observable as straining, although movement of the kittens may be felt through the abdominal wall. There is little else to see at this stage except repeated visits to the prospective kittening bed, and in the dependent type of cat, an apparent desire for reassurance from the owner. Some scratching up and bed-making occurs, and panting may be seen as a late first stage feature. Vaginal discharge is rarely seen and is usually licked away promptly by the cat. In the cat kittening for the first time, the first stage can be very prolonged, even lasting up to 36 hours without being abnormal.