Early Pregnancy in Pigs: Clear Signs & Detection Methods.

Early pregnancy detection in pigs is an important aspect of managing a successful breeding program. Confirming if a sow has conceived allows for better resource planning, healthcare, and farrowing preparation. Missing this window can result in feed waste, loss of valuable time, or poor reproductive performance.

Farmers who master the skill of early pregnancy detection can improve piglet survival rates and make timely decisions in pig management.

Observe Behavioral Signs

One of the earliest and most practical methods for assessing pregnancy in pigs is by observing their behavior after mating. A sow that has conceived typically will not return to estrus. If the mating was successful, she will not show heat symptoms during the next cycle, which usually occurs 18 to 24 days after breeding.

Signs of heat include increased vocalization, restlessness, a swollen vulva, and a strong standing reflex when pressure is applied to the back. If none of these signs appear during the expected return-to-estrus period, the sow is likely pregnant.

However, behavioral observation alone can be misleading. Pseudopregnancy, silent heat, and environmental factors can interfere with accuracy, so combining this method with other signs is more effective.

Monitor Appetite and Body Behavior

After conception, many sows exhibit subtle changes in feeding habits and behavior. Some may show an increased appetite a few weeks after breeding, which corresponds with hormonal changes during early gestation. Others may appear calmer and spend more time resting.

Physical discomfort may reduce activity levels. Watch for a gradual increase in belly size, especially after day 30 of pregnancy. However, abdominal enlargement becomes more visible in later stages, making it less useful for very early detection. Still, these slight shifts in appetite and movement, when tracked regularly, offer important clues about the sow's reproductive status.

Check Changes in Vulva Appearance

Physical examination of the vulva can give early hints about pregnancy. A sow that is not pregnant may display a swollen or reddened vulva during her next estrus. On the other hand, if pregnancy occurs, the vulva remains pale and relaxed in tone. This change may seem minor, but it becomes more noticeable when compared across multiple cycles.

Keep records of vulva characteristics at different stages to detect subtle differences. Visual monitoring should be performed calmly to avoid stressing the sow, as excessive movement or poor handling can interfere with reproductive health.

Use a Boar for Heat Detection

A tried-and-true farm method involves using a mature boar to detect returns to estrus. Bring the boar close to the sow between days 18 to 24 post-mating. If the sow stands firmly and allows the boar to mount, likely, she is not pregnant. If she avoids the boar, remains passive, or shows no interest, there’s a higher chance of successful conception.

To improve reliability, repeat this test over two to three heat cycles. This method requires experience and proper handling of animals to ensure safety and accuracy. Using a teaser boar can help minimize unwanted mating while observing the sow’s reaction closely.

Apply Pregnancy Diagnostic Tools

For more accurate confirmation, consider using diagnostic tools such as an ultrasound or hormonal assays. Ultrasonography is the most reliable and widely used method on commercial pig farms. It can detect pregnancy from as early as 25 to 30 days after breeding. The device uses sound waves to identify fluid-filled uterine structures and, later, fetal movement.

If ultrasound is unavailable, hormonal blood tests are another option. These detect progesterone or other pregnancy-related hormones and can confirm pregnancy by day 21 to 28 post-mating. Hormonal tests are ideal in farms without ultrasound access but require sample collection and lab analysis.

Track Body Condition and Mammary Changes

Pregnant sows gradually gain weight, particularly around the midsection, and show changes in their udder as gestation progresses. While these signs are clearer after day 50, some experienced farmers can detect subtle firmness in the mammary glands as early as day 35, especially in sows that have farrowed before.

Keep regular records of the sow’s body condition and appearance. Early swelling of the mammary area, slight udder development, or a firmer abdominal line can give useful insight. These observations, when combined with other signs, offer better confidence in identifying early pregnancy.

How to Manage Pigs After Pregnancy Is Confirmed

Once pregnancy is confirmed in pigs, effective management becomes critical to ensure the health and productivity of both the sow and her developing litter. The right strategies reduce pregnancy loss, improve farrowing outcomes, and increase piglet survival rates. Below are key areas to focus on after confirming that a sow is pregnant.

Adjust the Nutrition Plan

Pregnant pigs require a balanced diet specifically designed to support fetal growth, maternal health, and subsequent lactation. During the first 2–3 weeks after conception, it is best to maintain moderate feeding levels to help implantation succeed. Overfeeding early in pregnancy can negatively affect embryo development.

As gestation progresses, particularly from day 75 onward, energy and protein requirements increase. Including vitamins such as A, D, and E, and minerals like calcium, phosphorus, and selenium, supports skeletal development in piglets and helps prevent complications, including weak piglets or poor milk production.

Use gestation-specific feed formulations and avoid sudden dietary changes that may stress the sow.

Provide Comfortable and Safe Housing

Housing must offer protection from temperature extremes, drafts, and stress-inducing conditions. Sows should be moved to designated gestation pens that are clean, dry, and well-ventilated. These pens should allow space for movement while avoiding overcrowding.

Group-housed sows must be monitored to prevent aggression and competition for feed. Low-ranking sows often lose condition when forced to compete for resources. If aggression persists, consider moving the sow to an individual stall with proper bedding and sufficient space.

Monitor for Health and Behavioral Changes

Regular observation helps detect early signs of stress, illness, or discomfort. Healthy pregnant sows maintain appetite, body condition, and mobility. Signs such as lameness, disinterest in feed, or excessive restlessness may indicate a developing problem.

Parasite control is important throughout pregnancy. Internal and external parasites weaken the sow’s immunity and impact piglet health. Deworming under veterinary supervision and maintaining strict hygiene in living areas reduces parasite burdens.

Minimize Stress Throughout Gestation

Stress during pregnancy can lead to abortions, hormonal disruptions, or weak piglets. Avoid rough handling, loud noises, or sudden changes in routine. Limit the transport of pregnant sows, especially during the early and late stages of gestation when the risk of embryo loss is higher.

Introduce new animals to gestation groups cautiously. Sudden changes in social hierarchy often lead to fighting, which elevates cortisol levels and may endanger the pregnancy.

Schedule Routine Veterinary Checkups

Work closely with a veterinarian throughout the sow’s pregnancy. Routine health exams ensure the pregnancy is progressing normally and help detect issues such as urinary tract infections, metabolic disorders, or reproductive abnormalities.

A vet can perform ultrasound scans to check fetal development and viability. These scans offer reassurance that the pregnancy is on track or provide an early warning if intervention is needed.

Prepare for Farrowing in Advance

From day 100 onward, begin preparing for farrowing. Ensure the farrowing area is thoroughly cleaned, disinfected, and dry. Introduce the sow to the farrowing pen around day 110 to allow her to adjust to the new environment before giving birth.

Gather essential farrowing supplies like clean towels, iodine for umbilical cord treatment, gloves, and warming lamps for piglets. Make sure water and feed access are available and that the pen is quiet and secure.

Track Progress and Maintain Records

Accurate records help track gestation progress, feeding schedules, vaccinations, and any health incidents. Recording this information makes it easier to detect patterns, anticipate farrowing dates, and manage future breeding plans more efficiently.

Using digital tools like My Piggery Manager can simplify record-keeping by allowing you to monitor the pregnancy timeline, treatments, and piglet performance, all from one platform.

Conclusion

Early pregnancy detection in pigs is a vital part of successful herd management. It allows farmers to make informed decisions about nutrition, housing, healthcare, and farrowing preparations. While behavioral signs and physical changes offer initial clues, combining these observations with diagnostic tools like ultrasound or hormone testing increases reliability.

Tracking each sow’s reproductive cycle using digital tools improves accuracy and helps avoid unnecessary delays or mistakes. With a consistent and well-organized approach, farmers can support healthier pregnancies, boost piglet survival, and improve the overall productivity of their pig farming operation.