How Long is a Horse Pregnant?
Mares carry their foals for approximately 340 days, which is roughly 11 months. Normal gestation ranges from 320 to 370 days. Thoroughbreds and warmbloods may vary slightly from this average, and maiden mares sometimes carry a few days longer.
Horse Gestation Period Explained
The horse gestation period of 340 days is divided into early, middle, and late stages. During the early stage, fertilized eggs implant in the uterus and embryonic structures begin to form. The middle stage is characterized by rapid organ and skeletal development. In the final stage, the offspring reach near-birth size and the mother prepares instinctively for delivery by seeking a safe, quiet environment.
How to Calculate Horse Due Date
To calculate your horse's due date, simply add 340 days to the confirmed mating or conception date. This gives you the Estimated Due Date (EDD). Since births rarely fall on the exact calculated day, our calculator also shows a 5-day delivery window on either side. Use the form above to get instant results.
If your animal was bred across multiple days, enable the Date Range option. Enter the first and last breeding dates and the calculator will display both the earliest and latest possible delivery dates, giving you the complete expected birth window.
Signs of Pregnancy in Horse
Early signs include cessation of estrus cycles, subtle behavioral changes, and very mild udder development. By month 7 to 8, the belly becomes visibly enlarged. Teat waxing, a waxy discharge from the teats, typically appears 24 to 72 hours before foaling.
Pregnancy Stages
Month 1 to 3: Embryo development; heartbeat detected by day 26. Month 4 to 7: Fetal growth, limb and major organ formation. Month 8 to 10: Rapid weight gain; foal begins positioning for birth. Month 11: Final tissue maturation; hindquarter ligaments relax in preparation for delivery.
Care Tips During Horse Pregnancy
Ensure the mare receives a balanced diet rich in calcium and phosphorus, especially from month 8 onward. Maintain regular vaccinations, deworming, and dental care throughout pregnancy. Prepare a clean, spacious foaling stall and have your vet's contact ready as the due date approaches.