Pregnant Pig Symptoms: A Week-by-Week Guide for First-Time Pig Keepers (1, 2 & 3 Month Signs)

The first few weeks after conception are a delicate dance, and with pigs, this early stage is critical for ensuring that tiny embryos take hold and thrive. Careful attention to diet, stress, and environment can make all the difference.

For first-time pig keepers, understanding what to expect each week of pregnancy isn’t just helpful it’s essential. From subtle changes in behavior to early physical signs, this week-by-week guide will walk you through the 1st, 2nd, and 3rd months of a sow’s pregnancy, helping you spot the telltale signals that new piglets are on the way.

Understanding the 3-3-3 Rule (The 114-Day Clock)

Pregnancy in pigs is both fascinating and critical to manage correctly, especially for first-time pig keepers. The “3-3-3 Rule” refers to the universal gestation period of pigs: 3 months, 3 weeks, and 3 days, or approximately 114 days from conception to farrowing. This simple rule serves as a reliable clock to track the sow or gilt’s progress, anticipate developmental milestones, and plan feeding, housing, and care strategies.

For gilts first-time pregnant females special attention is required, as their bodies and behavior differ slightly from experienced sows. By understanding this clock, you can reduce stress for both the mother and her litter, ensure timely interventions, and maximize the chances of a successful, healthy farrowing.

Early Confirmation: Weeks 1–4 and the Primary Test

The 21-Day Cycle Check (The Most Reliable Indicator)

One of the earliest and most dependable ways to determine whether a sow or gilt is pregnant is by tracking her heat (oestrus) cycle. Most female pigs come into heat approximately every 21 days if they are not pregnant. For a gilt or sow, the absence of heat after 18–24 days post-mating is the first reliable sign that pregnancy has occurred.

To perform this check effectively, boar exposure is key. Introduce the female to a boar at the appropriate time, ideally twice a day, and carefully record her reactions. A receptive sow will exhibit the classic signs of standing heat: swollen vulva, reddened clitoris, vocalizations, restless behavior, and, most importantly, a standing reflex when gentle back pressure is applied. If these signs are absent during the expected window, it is a strong early indicator that she is pregnant.

Recording each female’s response to boar presence during the first month is essential for establishing a baseline. This initial tracking helps you identify subtle changes in behavior and determine with confidence whether to continue routine management or prepare for pregnancy care.

Behavioral Clues (Subtle Signs, Weeks 1–4)

While the absence of heat is the most definitive early indicator, careful observation of behavioral changes can provide additional clues during the first month:

• Increased calm or mild lethargy: Pregnant gilts often appear slightly less active than before breeding. They may move more slowly or rest more frequently, a subtle shift from their normal energetic behavior.
• Appetite changes: Some females may eat slightly more due to early gestational demands, while others may show a slight decrease in appetite. These shifts are typically modest but consistent across the first few weeks.
• Reduced social interaction or fighting: Pregnant pigs may show less interest in aggressive behaviors or playful mounting. They may avoid interactions they previously sought out, particularly with other females, as their energy is redirected toward early fetal development.

By combining the 21-day cycle check with careful behavioral observation, first-time pig keepers can gain early confidence in pregnancy detection and adjust feeding, housing, and care routines accordingly.

Month 1 Symptoms (Weeks 5–8): The Non-Visual Period

During weeks 5 to 8 of gestation, pregnancy in pigs remains largely non-visible, but several subtle changes can be observed in body condition, eating habits, and housing requirements. Recognizing these early signs ensures proper care and prepares the sow or gilt for the next stages of pregnancy.

Changes in Body Condition

Although the abdominal enlargement typical of later pregnancy is not yet apparent, gradual weight gain begins around this period. Pregnant sows often appear slightly fuller and firmer, with subtle increases in body mass that experienced keepers can detect through routine observation.

Hormonal shifts during early gestation also positively influence the skin and coat condition. Many sows display a healthier, glossier coat, reflecting changes in metabolism and overall well-being. Monitoring these early physical cues alongside behavioral observations can provide additional confidence in pregnancy confirmation.

Digestive and Eating Habits

By this stage, most pregnant sows begin to show consistent changes in appetite. Some may consume more feed than usual, reflecting the energy demands of early fetal development, while others maintain a steady intake.

Maintaining a consistent feeding routine is crucial during weeks 5–8. Overfeeding or sudden dietary changes should be avoided to prevent digestive disturbances or stress. Feeding should focus on high-quality, nutrient-rich feed appropriate for gestation, including grains, green fodder, and a balance of vitamins and minerals, particularly calcium and phosphorus for fetal skeletal development.

Regular monitoring of feed consumption provides insight into the sow’s health and early pregnancy progression. A sudden drop in appetite or unusual feeding behavior may indicate stress, illness, or early gestational complications.

Housing & Environment Needs

Weeks 5–8 mark a critical period for transitioning the sow or gilt into a dedicated gestation space if she has not already been moved. Proper housing supports comfort, minimizes stress, and reduces the risk of injury or competition among group-housed sows.

The gestation pen or area should be:

• Clean, dry, and well-ventilated, protecting against drafts and temperature extremes.
• Spacious enough for movement while preventing overcrowding.
• Equipped with comfortable bedding, promoting restful periods and supporting early fetal development.

Minimizing stress during this period is key. Avoid frequent handling, loud noises, and abrupt changes in routine, as early gestation is sensitive to environmental stressors that can affect implantation and embryo survival.

Month 2 Symptoms (Weeks 9–12): Visible Development

Mammary Gland and Udder Development

• Teat prominence: By weeks 9–12, the sow’s teats become more noticeable. This is one of the earliest visible pregnancy indicators for a 2 month pregnant pig.
• Mammary swelling: Mammary tissue begins to fill out gradually, signaling the onset of colostrum production in preparation for farrowing.
• Observation tip: Record teat size and firmness weekly. Early detection of abnormal development can indicate health issues or hormonal imbalances.

Abdominal Swelling

• Visible pregnancy: The belly starts to drop, becoming visibly distended. This is the period when a sow truly looks pregnant to the naked eye.
• Body condition monitoring: Track abdominal expansion to ensure healthy fetal growth. Uneven or delayed swelling may indicate developmental problems in the litter.
• Environmental consideration: Ensure that housing provides enough space for the expanding abdomen to avoid stress or injury from cramped quarters.

Activity Levels

• Behavioral changes: Sows typically become calmer, spend more time resting, and show reluctance to move quickly.
• Management implication: Reduced activity reflects a mature 2 month pregnant pig conserving energy for fetal development.

Observation: Monitor resting behavior; excessive lethargy or disinterest in feed may indicate health problems that require veterinary attention.

Month 3 Symptoms (Weeks 13–Farrowing): The Final Stage and Prep

Fetal Movement

• By now, piglets are actively moving in the uterus. You can often feel them kicking or shifting against the sow’s flanks, particularly along the sides and lower abdomen.
• Observing these movements helps confirm healthy fetal development and lets you monitor individual piglet activity for potential issues.
• Tip: Gently stroke the sow’s side and watch for subtle bumps or shifts; sudden inactivity may indicate stress or discomfort.

Udder Confirmation

• Mammary glands are fully engorged and firm, signaling that the sow is preparing for lactation.
• Nipples may begin waxing (white, thickened secretions) or even dripping colostrum, a clear sign that labor is imminent.
• Regularly check the udder for swelling, heat, or signs of discomfort to ensure proper milk development and readiness for piglets.

The Start of Nesting Behavior

• Nesting is a critical pre-farrowing behavior and usually appears during the last week of gestation.
• The sow may:
  • Paw at bedding or flooring
  • Rearrange straw or other materials
  • Bite or nudge the pen floor to create a nest
• Nesting behavior indicates the sow is instinctively preparing a safe, comfortable environment for her piglets. Monitoring this behavior helps you anticipate farrowing and prepare the farrowing pen accordingly.

Key Management Tips for Month 3

• Ensure the farrowing pen is clean, dry, and secure to reduce stress.
• Maintain a quiet environment; excessive noise or sudden handling can trigger premature labor or stress.
• Begin monitoring closely for early signs of labor: restlessness, frequent lying down and standing, or mild contractions.
• Keep water and feed readily available, but avoid overfeeding, which can hinder movement during labor.

By observing fetal movement, udder development, and nesting behavior, you can confidently track your sow’s health and anticipate farrowing, ensuring a safer, more successful delivery for both sow and piglets.

The Final Hours: Signs Labor is Imminent

Mucus and Vulva Swelling

• In the last 12–24 hours before farrowing, the sow’s vulva becomes visibly swollen, soft, and relaxed.
• A clear, stringy mucus discharge often appears, which lubricates the birth canal and indicates that cervical dilation is beginning.
• These changes are a reliable visual cue that the sow is entering the active stage of labor.
• Regular, calm inspection of the vulva can help differentiate true farrowing signals from normal late-pregnancy variations.

Temperature Drop (The 12–24 Hour Signal)

• A drop in rectal temperature of 1–2°F (0.5–1°C) is one of the most consistent physiological indicators that farrowing will occur within a day.
• Measure the sow’s temperature twice daily in the final 2–3 days of gestation to catch this subtle but critical change.
• This window provides time to prepare the farrowing pen, gather supplies, and ensure help is available, reducing stress and potential complications.

Hyper-Nesting and Anxiety

• The sow will display intensified nesting behavior, which is instinctive preparation for the upcoming litter.
• Behaviors may include:
  • Pawing and digging at bedding or pen floor
  • Shredding straw or moving bedding repeatedly
  • Circling or pacing the pen with focus
  • Heavy breathing and frequent posture changes
• This stage reflects the sow’s heightened maternal drive and indicates that contractions are likely to begin soon.
• Monitoring nesting intensity provides a behavioral forecast of when labor will transition to active farrowing.

Practical Management During the Final Hours

• Environment: Keep the farrowing pen clean, dry, quiet, and at a comfortable temperature to reduce stress.
• Nutrition and Hydration: Offer water freely and light feed if the sow is willing, but avoid overfeeding.
• Observation: Watch for the onset of contractions and initial piglet presentation. Be ready to intervene if there are signs of prolonged labor or dystocia.
• Minimize Stress: Avoid unnecessary handling, loud noises, or sudden disruptions. Stress at this stage can slow labor and increase risks to both sow and piglets.
• Preparedness: Have farrowing tools ready—clean towels, gloves, iodine, and warming lamps for piglets.

By closely monitoring vulva changes, rectal temperature, and hyper-nesting behaviors, you can accurately predict labor onset. Proper preparation during this window ensures a safer farrowing process, reduces piglet mortality, and supports sow well-being, allowing the natural birthing process to proceed with minimal complications.