Piglets do not have the ability to keep themselves warm when they
are born, so it is necessary that warmth is provided in the
farrowing pen, and it is essential that the farrowing pen is kept
clean at all times to prevent the piglets from getting sick.
Long before the sow is ready to give birth you should have a
special pen set up for her with plenty of clean, and dry straw,
warmth and lots of room. This is generally called a farrowing pen.
It is excellent if you have a birthing pen for her, and then
after she gives birth move her and the piglets to the farrowing
pen so that the farrowing pen is nice, sanitary and clean.
You should also consult with the veterinarian to either get the
initial immunization shots for the piglets to administer when
they are born or have the veterinarian administer them very
shortly after the sow gives birth.
Pigs quite often have stillbirths or re-absorb embryos. Embryos are not embedded until day nine of gestation and at that stage they can migrate from one horn (side of the uterus) to another, so if all embryos are lost in one horn they can migrate from the other one. As long as there are four embryos in place, and both horns are occupied, pregnancy continues beyond ten days, otherwise it appears to be terminated.
After twelve days the number of embryos may be reduced to as few as one and the pregnancy will still continue. Litters of four or less are suggestive of embryonic death between twelve and thirty days of gestation. Embryos destroyed before day thirty-five of gestation are absorbed, as they have not yet begun skeletal calcification and sometimes foetuses can become mummified if they die after thirty days.
Older sows have a higher percentage of stillbirths than younger sows but this may be connected with litter size, as older sows tend to have larger litters with smaller piglets than do younger pigs. There are various causes of abortion, stillbirths and foetal deaths; these include bacterial or viral infections, nutritional deficiencies, poisoning and so forth.