How To Tell If A Pig Is Pregnant: Step-By-Step Guide


Is My Pig Pregnant?

If you are breeding pigs for the first time, you will need to familiarize yourself with the signs that your pig may (or may not) be pregnant. It is important to know the breeding status of your pigs for a number of reasons, and the earlier the better.

How can you tell if your pig is pregnant? One of the earliest methods to estimate pregnancy is by observing whether your pig goes into heat based off of her next estimated cycle. You can also determine pregnancy by the changes to the teats, the changes to the vulva, behavioral changes, and her lack of interest in mating. You may also choose to purchase pregnancy test strips or have a vet confirm pregnancy, if you are willing to spend the money.

Some signs of pregnancy are present within a few weeks of mating, and some will not make themselves known until days before giving birth. Read on to learn more about the signs of pig pregnancy, from the earliest signs, to the signs present just prior to farrowing. 

Evidence Of Pregnancy in Pigs #1: Behavioral Changes

I am listing behavioral changes as the first sign of pregnancy in pigs because you may notice these changes at any time during the pregnancy. You may notice behavioral changes shortly after conception, or you may not notice changes in behavior at all. This might sound vague, but it is entirely dependent on your individual sow and her personality. She may become especially friendly, or she may become aggressive. She may isolate herself from the herd, or she may desire more attention. She may become more active, or she may rest more. There are a number of behavioral changes that can occur during pregnancy that may be obvious to you if you know your pig and her typical temperament. 

Want to know more about female pigs? Visit my article What a Female Pig is Called & Other Female Pig Facts.

Evidence Of Pregnancy in Pigs #2: The Estrus Cycle

A pig’s estrus cycle is approximately 21 days long. This means that if your pig is not pregnant after mating, you can attempt another breeding in a few weeks when she goes into heat again. If your pig goes into heat again, this is a sure sign that she is not pregnant. It is worth mentioning that pigs have a naturally high rate of pregnancy success – it has been shown that as much as 77% of matings result in pregnancy. The high rate of success combined with the short estrus cycle means that you likely will not have to wait long before a successful pregnancy.

What are some of the signs of heat? When a gilt (unbred or first-time mother) or a sow is in heat, she will often show a swollen and red vulva, and/or discharge. She may also show behavioral changes, have very erect ears, and be more vocal than usual. The most obvious sign of heat, however, is her interest in boars.

A gilt or sow in heat will almost always show an interest in boar and will be receptive to his advances. Using AI and don’t have a boar that you can use to test this? You can use yourself – stand next to your pig and press firmly on her back. If she is in heat, she will reflexively stand still. If she is not in heat, she will run away. 

A pregnant gilt or sow will show no interest in the boar (or in standing still for your pressure tests). Likewise, a boar will often show no interest in her, instead choosing to spend his time seeking a pig in heat. If an overactive boar does decide to mount a pregnant gilt or sow, she will usually reject his advances. 

Evidence Of Pregnancy in Pigs #3: Pregnancy Tests

As is true for humans, there are pregnancy test strips that you can purchase online for your pig. Pregnancy test strips will detect pregnancy through the presence of specific hormones in the sow’s urine. Make sure that you purchase tests specifically designed for swine – the hormone levels will differ between species. These tests can detect pregnancy as early as 20-30 days after mating.

A vet can also come out and perform a more accurate test, often using an ultrasound machine. This is not economical for most pig breeders, but if you are a small pig keeper and would like to confirm pregnancy, this is an option and can typically detect pregnancy between 30 and 80 days from conception.

Evidence Of Pregnancy in Pigs #4: Swollen Teats

Because of the pig’s body shape, you will not always be able to detect pregnancy by observing physical changes to the abdomen. Pigs have naturally round bellies, so a pregnant pig – even a heavily pregnant pig – can often look no bigger than her sisters. While you can’t rely on visually inspecting the abdomen to detect pregnancy, you can likely detect changes to the teats. Toward the end of the pregnancy, your pig’s teats will begin to swell and fill with milk. This change will begin with the rear teats and will slowly push forward to the remaining teats, until all of the udder is visibly swollen with pointed teats.

To the trained eye, this change is often detectable about 30 days from farrowing. Older, more experienced sows will not display this swelling until a bit later – around 2 to 3 weeks prior to farrowing. If your sow allows it, try to express one of the teats – if you get milk, you can usually expect piglets within the next 48 hours. 

Evidence Of Pregnancy in Pigs #5: Changes To The Vulva

The appearance of the vulva can tell you a lot about the status of a gilt or sow – it can tell you that a pig is in heat, and it can also (sometimes) tell you if a pig is pregnant. Once your sow becomes heavy with piglets, her abdomen will begin to pull toward the ground, which will cause swelling to the reproductive organs and will often “tilt” the vulva so it is pointing upward. This change is not present in all pigs, but can be a sign of pregnancy nonetheless. 

Looking to breed pigs for meat? Check out my article Meat Pig Breeds: 8 Best Pig Breeds For Meat.

Evidence Of Pregnancy in Pigs #6: Nesting Behaviors

A few days before farrowing, your sow may become restless. She may become more vocal, and will often isolate herself from the herd. During this time she will begin nesting. She will locate a suitable place to farrow (usually one that is provided to her by her keepers), and will begin the process of collecting and arranging material for her farrowing nest. You can help prepare for this by putting various materials around the farrowing site, as well as fresh, clean straw in her birthing shelter.

Pig Gestation Period

My hope is that you will be able to accurately diagnose pregnancy in your pig with the following tips. If your sow is particularly secretive about her pregnancy and you are truly stumped, take heart in that you will not have to wait long for confirmation – the gestation period of a pig is 3 months, 3 weeks, and 3 days (or 109-114 days). If your pig is pregnant, you will not have to wait long for the real evidence.

Why It Is Important To Know If Your Pig Is Pregnant

There are a few reasons why you will want to be aware of your pig’s pregnancy. You will want to know if your pig is pregnant so that you can offer her the extra care that she needs during gestation, so that you know whether or not to expose her to mating again, and so that you know whether or not to expect piglets.

While pigs are by no means delicate creatures, your pregnant sow will need a little extra care while in the family way. You will need to adjust her diet as necessary, and you may need to practice some herd management depending on her behavior and the behavior of her herd-mates.

You are probably wondering at your pig’s pregnancy status because you intentionally bred her. If that is the case, you will want to know if the breeding took or not, so that you can plan whether you will expose her to a boar (or AI) the next go around. If she is not pregnant, you will want to attempt breeding during her next heat. If she is pregnant, you will not need to worry about it.

Lastly, you will want to know if your sow is pregnant so that you can prepare for piglets. Piglets require a few special considerations – including an isolated sow, a safe and secure farrowing (birthing) area, and a heat lamp. If you are caught unaware, your piglets could suffer for it. 

Pregnant Pigs Are Forgiving

As you are learning about your pigs, there will initially be a lot of trial and error. You may even miss the signs of pregnancy until it is too late to prepare. If this happens, don’t fret – most sows make excellent mothers and will instinctively take care of their piglets without any intervention from you. Sows know what to do, and can be quite forgiving while their keepers are learning. 


Having a surprise litter of piglets show up can catch you off guard financially. It’s important to know what financial commitment you’re in for when caring for pigs. To get a complete rundown, visit my article How Much it Costs to Raise Pigs: Complete Expense Guide.


Carmella Abel

Hello! I’m Carmella. I’ve spent my entire life around farm animals, and I created Savvy Farm Life to share the helpful information I’ve learned over the years. Thank you for stopping by, and best of luck with your farm!

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