If you’re contemplating breeding your horse and having a safe and healthy pregnancy, there is much more you need know than just how long your horse will be pregnant for.
What is the first month of a horse’s pregnancy? In short, horses are pregnant for 10 to 12 months, and most mares only carry one foal per pregnancy – however, although rare, twins do sometimes appear.
But how long can horses carry a pregnancy? For a more specific answer on a horse’s gestation period, horses typically tend to be pregnant for 326 days to 354 days, however, there are cases where prolonged gestation has lasted as long as nearly 370 days.
Horses are polyestrous periodically, did you know that? This means that your mare has a fertility season similar to that of a cat in that she will experience several cycles during a particular season – with their cycle being during periods of longer daylight length. It is believed that this cyclical pattern is an evolutionary adaptation that guarantees the mare will give birth in the spring, when conditions are at their most favourable.
A mare may normally only have one pregnancy each year, giving birth to one foal in that year, due to this and the length of time a horse is pregnant.
How Long are Miniature Horses Pregnant?
Miniature horses and all other breeds of female horses normally carry their babies for about 11 months, which is similar to how long other horses remain pregnant. The average miniature mare will carry her foal for around 330 days before she gives birth – with the actual length of pregnancy lasting from 320 days to 380 days.
Understanding the Cycle of a Mare
In order to handle your mare well in general and to successfully breed her, you must have a solid grasp of her life cycle. As mares are seasonally polyestrous, the mare will be light responsive, resulting in a start of her cycles caused by a decrease in melatonin from increasing daylight hours.
Among the dates that horse breeders should keep in mind are:
- The longest day of the year and the height of the natural mating season is the Summer Solstice.
- The autumnal transition begins during the equinox, when there is an equal amount of daylight and darkness throughout the day.
- Mares will be in their deepest anestrus on the Winter Solstice, which is also the shortest day of the year.
- The mare will be in a springtime transition at the spring equinox, another period when there is an equal amount of light and dark throughout the day.
The times listed above vary from year to year, so do your homework to find out when you may start mating your mare in that particular year. The beginning of cyclicity may also be affected by temperature since it is most likely partially controlled by a neurotransmitter that is involved in prolactin production. It is also commonly accepted that the onset of the mare’s mating season may be triggered by the removal of opioid inhibition from the gonadal axis.
Finally, there are seasonal effects that can affect the gestation period of the mare. Mares that were bred in the first quarter of the year frequently carry their foal for a little bit longer than anticipated, while mares bred during seasons with longer days may have a little bit shorter gestation period.
Some other factors that can affect how long a horse is a pregnant include whether the foal is a colt or a filly – with the period for colts being up to seven days longer than fillies. The length of a horse’s pregnancy may also be influenced by body weight; lighter mares often have longer gestations than heavier ones.
How Long are Horses Pregnant? 6, 7, and 9-Month Pregnant Horses Explained

Pregnant mares will go through three trimesters with the first beginning at conception and being confirmed at around two weeks. The mare must have a veterinary examination during the first trimester to ensure both she and her foal are in excellent condition.
The veterinarian will be able to use an ultrasound at around day 25 to find the foal’s heartbeat and determine its viability. Additionally, twins may be verified around this time. If a mare is found to have twins, the veterinarian may ask if the owner wishes to terminate the second embryo in order to give the mare and the remaining embryo a better chance of survival.
When a horse is three months pregnant, an ultrasound will be performed. The results will reveal what seems to be a horse, with recognizable traits and the gender.
A 6-month pregnant horse will begin to show that they are pregnant, with the second trimester beginning at day 114. The mare may have immunizations and a dewormer at this period. The mare’s diet should be increased as well to provide her the nourishment she needs to achieve the objective.
A horse 7 months pregnant, and in her third trimester at 226 days, will require more frequent vet visits – with regular exercise needing to be stopped from the seventh month. A horse that is nine months pregnant will soon give birth, therefore it’s crucial to keep your mare in a relaxed and comfortable atmosphere as she gets closer to giving birth.
Leading up to Birth – 11-Month Pregnant Horses
The foaling day will soon arrive for an 11-month-old pregnant horse; on average, this may occur between day 326 and day 354. There are also some test kits some breeders use that help to anticipate the due date, and these can be useful on the mare’s first birth as their foaling process will be unknown.
The mare’s body will begin to exhibit indicators of readiness for birth in the days before delivery. This can include a full-looking udder, dripping milk, and a low-hanging belly.
During the near-birthing period, the mare should be provided plenty of fresh straw and hay to provide enough comfort. She will most likely paw at the ground and become restless while she goes into labor, but she will give birth while lying down.
Typically, the first thing to be visible during the birthing process is the amniotic sac, followed by the head and the legs of the foal itself. It usually takes just a few minutes for the foal to be delivered after the amniotic sac is seen.
Labour and Delivery – What you Should Know
It’s interesting that most mares give birth at night. This may be a survival strategy that enables the mother and foal to be prepared to flee when daybreak comes.
The mare will be agitated in the early stages of labor and may start kicking at her stomach and engaging in nesting behavior. Additionally, a lot of mares perspire when giving birth, which is known as the mare “heating up.” Wrap her tail and clean around the perineum for the next hour.
The second stage of labor lasts just for up to 25 minutes on average. Continuous progress through your mare’s labour should reveal the foal’s front hooves, nose, and ears.
A veterinarian should be present to check the foal’s respiration after delivery; if not, the breathing may need to be promoted by delicately massaging the foal’s nostrils with a blunt item or by rapidly rubbing them with a cloth.
Iodine-based disinfection of any biologicals used for exhibiting is another suggestion for the delivery of a foal. It is also advised that the umbilical cord should not be cut immediately as it is believed that a certain amount of blood still flows into the goal after birth through the umbilical artery.
In the third stage of labour, after the foal has been born, you’ll be waiting for the placenta to pass. It should be treated as an emergency and a veterinarian should be consulted if the placenta does not discharge within three hours.
The foal should be standing within an hour after birth and should also demonstrate the ability to nurse within two hours. Typically, the mare herself shouldn’t need any post-partum care.