A pregnant pig will give you a reliable sequence of signals in the final days and hours before she farrows, starting with physical changes you can spot about a week out and building to unmistakable behavioral shifts in the last 24 hours. Pig gestation averages 115 days, with a normal range of 105 to 125 days, so knowing your breeding date gives you a window to start watching closely. Here’s what to look for and when.
Changes in the Udder and Vulva
The earliest visible sign usually appears about 10 to 14 days before farrowing, when the udder begins to enlarge and the teats become firmer. Starting around day 105 of gestation, the milk-producing tissue in the udder actively shifts into gear, with cells filling with milk droplets and reorganizing for lactation. You’ll notice the teats looking fuller and more defined as this process accelerates.
In the final 24 to 48 hours, you can often express a small amount of colostrum (thick, yellowish first milk) by gently squeezing a teat. If milk flows freely with light pressure, farrowing is very close, typically within 12 to 24 hours. The vulva also swells and relaxes noticeably in the last two to three days, becoming puffy and sometimes reddened. A thin, clear or slightly mucous discharge from the vulva is normal during this stage.
Nesting Behavior
Nesting is one of the most reliable behavioral indicators, and it follows a predictable pattern. A sow will start gathering and arranging bedding material roughly 24 hours before she farrows, pawing at the ground, rooting straw or hay into a pile, and circling her chosen spot. This activity intensifies as the clock ticks down. Research tracking sows with continuous video found that nesting activity roughly doubles between the 24-to-12-hour window and the final 12 hours before birth, peaking between 8 and 4 hours before the first piglet arrives.
If you provide straw, hay, or other loose bedding, you’ll see her actively mouth it, carry it, and push it into place. Sows on concrete or bare flooring still go through the motions, pawing and rooting at the floor even with nothing to gather. This driven, repetitive behavior is hormonally triggered and hard to miss once you know what you’re looking at.
What First-Time Mothers Do Differently
If your pig is a gilt (first-time mother), expect the signs to be less textbook. Gilts tend to be more restless in the 24 hours before farrowing, changing positions frequently rather than settling into the steady lateral lying that experienced sows adopt. They also show fewer of the classic pain-related postures like back arching. This doesn’t mean they’re in less discomfort. Research suggests gilts may simply express pain differently or be more reluctant to show obvious signs compared to sows who have been through it before.
Gilts may also be more unpredictable in their nesting. An experienced sow often builds a neat, deliberate nest and lies down in it; a gilt may pace, rearrange bedding repeatedly, and seem unsettled longer before finally committing to a spot. Give her extra patience and a quiet environment.
Signs in the Final Hours
Once you’re inside the last six hours, the signs become harder to ignore. One of the most measurable is breathing rate. A pig’s normal resting respiration runs about 25 to 30 breaths per minute. Five to six hours before farrowing begins, that rate can climb as high as 80 breaths per minute. You can count this yourself by watching her flank rise and fall for 15 seconds and multiplying by four.
Other signs in this window include:
- Restlessness and frequent position changes: She’ll get up, lie down, shift from one side to the other, and get up again.
- Loss of appetite: Many sows refuse their feed in the final 12 to 24 hours.
- Chewing or jaw movements: Repetitive chomping or chewing at nothing, sometimes with light frothing.
- Tail twitching: Rhythmic flicking or curling of the tail signals a piglet has entered the birth canal. This is one of the last signs before delivery starts.
Once visible contractions begin, with the sow lying on her side and her body tensing in waves, the first piglet typically arrives within one to three hours, though it can happen in minutes.
What Happens During Delivery
Piglets are born one at a time, and the typical interval between them is 15 minutes or less. Some come back to back within seconds; others take longer. The sow usually stays lying on her side through most of the process, occasionally getting up between piglets. Each piglet arrives in its own membrane, which the sow may or may not help remove. Piglets are remarkably quick to find a teat on their own, often nursing within minutes of birth.
A full litter can take anywhere from one to several hours to deliver, depending on litter size. Litters of 10 to 14 piglets are common in many breeds, and larger litters naturally take longer.
Warning Signs That Something Is Wrong
Most farrowings proceed without any problems, but knowing the red flags lets you act quickly when they don’t. The key intervals to watch are these: if more than two hours pass after the onset of labor with no piglet delivered, or if more than 45 minutes to an hour passes between piglets after delivery has started, the sow may be experiencing dystocia (difficult birth).
Other signs of trouble include heavy, unproductive straining for 30 minutes or more with no piglet appearing; foul-smelling or discolored discharge from the vulva; and a sow that seems depressed, feverish, or completely stops trying. A gestation that stretches past 116 days without any signs of labor can also indicate a problem.
The second piglet and the last piglet in a litter carry the highest risk of complications. The second because the birth canal is still relatively tight, and the last because the uterus is losing contractile strength. Oversized piglets (those with a crown-to-rump length over 31 centimeters) and stillborn piglets in the litter also increase the chance of difficult delivery. If you notice any of these warning signs, having a veterinarian’s number ready is worth more than any amount of waiting and hoping.
Putting the Timeline Together
Here’s a practical countdown based on what the research and experienced breeders consistently report:
- 7 to 14 days out: Udder begins filling, teats firm up.
- 2 to 3 days out: Vulva swells noticeably, may see clear discharge.
- 24 hours out: Nesting behavior starts, appetite drops.
- 8 to 4 hours out: Nesting peaks, restlessness increases.
- 5 to 6 hours out: Breathing rate rises sharply.
- 1 to 3 hours out: Visible contractions, lying on side.
- Minutes away: Tail twitching, fluid or membrane visible at vulva.
No single sign is perfectly reliable on its own. But when you see the udder changes, nesting, rapid breathing, and tail twitching stacking up together, you can be confident that piglets are on the way. Prepare your farrowing area, keep it warm (newborn piglets need an ambient temperature around 90°F in their first days), and let the sow do what she’s built to do.