Horse Giving Birth
The gestation period of a horse is usually 11 to 12 months. The mare will foal when she is ready and can accelerate or delay foaling as needed depending on things happening in the environment.
Most mares foal at night or early in the morning, and prefer to give birth alone when possible.
The actual birth process takes only a short time, about 15 to 30 minutes. Once the foal is born, the mare will lick the newborn to clean it and help blood circulation. In a very short time, the foal will attempt to stand and get milk from its mother. A foal should stand and nurse within the first hour of life.
Here's how it happens.
Update: View Horse Giving Birth Video