The third trimester of pregnancy is the final phase of your prenatal journey, typically spanning from Week 28 to Week 40. By now, you’ve experienced the early shifts of the first trimester and the growth spurt of the second. During this stage, your baby will make remarkable developmental strides, and you’ll begin mentally and physically preparing for labor and delivery. But when is the third trimester of pregnancy exactly, and what week does the third trimester start in pregnancy? In short, this pivotal stage kicks off at Week 28 and may extend right up until Week 40 (or 42 in some cases), culminating in the birth of your baby.If you’re wondering how many weeks is the third trimester of pregnancy, the answer is about 12 weeks, though it can vary slightly depending on your personal pregnancy progression.
This period can bring an assortment of new challenges like lower back pain pregnancy third trimester, pregnancy headaches third trimester, and pregnancy insomnia third trimester—but it can also be incredibly rewarding as you feel baby’s stronger kicks and active movements. In this post, we’ll cover everything from baby growth in the third trimester and common symptoms to diet in the third trimester of pregnancy, exercise during pregnancy third trimester, and birth preparation tips.
What Is the Third Trimester of Pregnancy?
The third trimester pregnancy phase typically begins at Week 28 and stretches to Week 40, although some women may go slightly beyond Week 40. According to the American College of Obstetricians and Gynecologists (ACOG), these final weeks are marked by:
- Rapid Fetal Development: The baby gains the most weight and prepares for life outside the womb.
- Physical & Hormonal Changes in the Mother: From nausea third trimester pregnancy (for some) to increased fatigue, the mother’s body is in full nesting mode.
- Preparation for Labor: Your body starts experiencing Braxton Hicks contractions, and the cervix may begin to soften as you approach your due date.
Most mothers notice that physical demands peak during this period. The belly is larger, causing shifts in balance, posture, and comfort. Emotional changes also tend to surface—mood swings, anxiety about delivery, and bursts of excitement as you realize you’ll soon hold your baby.
Baby Growth in the Third Trimester
During Weeks 28 to 40, your baby:
- Increases Weight Rapidly: Around Week 28, babies can weigh around 2 to 2.5 pounds. By full term (Week 40), the average weight is roughly 7 to 8 pounds (though each baby is unique).
- Develops Lungs & Other Organs: The lungs mature significantly in the late third trimester, making them better prepared for breathing post-birth.
- Builds Fat Reserves: This helps regulate body temperature after birth.
- Refines Brain Function: The cerebral cortex continues to develop, which improves your baby’s ability to detect sound, light, and even your voice.
- Prepares for Delivery: Often by Week 36, baby’s head moves into the pelvis (the cephalic or head-down position).
Your healthcare provider might schedule an ultrasound in third trimester to monitor growth, position, and amniotic fluid levels. Checking the baby’s well-being at this stage ensures that any concerns—like too little (oligohydramnios) or too much (polyhydramnios) amniotic fluid—are addressed promptly.
Common Symptoms
Despite the excitement about meeting your little one soon, the pregnancy third trimester can present its own series of discomforts and adjustments. Let’s break down some typical complaints you might experience.
Aches & Pains
- Lower Back Pain Pregnancy Third Trimester: With the uterus at its largest, additional pressure on your spine can cause soreness or sciatica. A supportive prenatal belt may help alleviate discomfort.
- Pregnancy Third Trimester Pelvic Pain: As pelvic joints loosen in preparation for birth (thanks to the hormone relaxin), you might feel pressure or even pain, especially when walking or changing positions.
- Abdominal Pain During Third Trimester of Pregnancy: Mild cramping often relates to Braxton Hicks contractions—these are “practice” contractions that shouldn’t be overly painful. Sharp or persistent pains may indicate an issue; consult your doctor if in doubt.
Pregnancy Headaches Third Trimester
Your body’s blood volume is at an all-time high, and fluctuating blood sugar levels or stress could trigger headaches. Stay hydrated, eat balanced meals, and speak with your doctor before taking any over-the-counter painkillers—acetaminophen (Tylenol) is often recommended, but always confirm safety with your healthcare provider.
Digestive Issues & Nausea
- Nausea Third Trimester Pregnancy: Some women see the return of morning sickness late in pregnancy, especially if they’re prone to heartburn or acid reflux. Eating smaller, frequent meals and avoiding spicy or greasy foods might provide relief.
- Constipation & Heartburn: The expanding uterus can press on the intestines and stomach, causing slower digestion. Fiber-rich foods, adequate water, and mild exercise can help.
Spotting or Bleeding
- Spotting During Pregnancy Third Trimester: Light spotting can sometimes occur following an internal exam or sexual intercourse due to a sensitive cervix. However, any heavier bleeding should prompt immediate medical attention.
Blood Pressure Changes
- BP in Pregnancy Third Trimester: High blood pressure (140/90 mmHg or higher) could be a sign of preeclampsia, especially when accompanied by swelling and protein in the urine. Regular check-ups and blood pressure monitoring are essential.
Pregnancy Insomnia Third Trimester
If you find sleep elusive due to constant bathroom trips, joint pain, or anxious thoughts about labor, you’re not alone. Many women battle pregnancy insomnia third trimester. Strategies to improve sleep include:
- Sticking to a Bedtime Routine: Aim for the same bedtime each night.
- Limiting Screen Time: Blue light can disrupt melatonin.
- Propping with Pillows: Support your bump and back. A maternity pillow can help you find a more comfortable position.
Danger Signs in the Third Trimester
Always call your OB-GYN or midwife if you notice any of these red flags:
- Severe or Sudden Abdominal Pain: Could indicate placental abruption or other serious complications.
- Heavy Bleeding or Gush of Fluid: Might suggest preterm rupture of membranes or a placental issue.
- Significant Swelling: Sudden swelling in the face, hands, or feet alongside high BP could signal preeclampsia.
- Decreased Fetal Movement: If you notice fewer than 10 movements within two hours, call your doctor immediately.
- High Fever or Flu-Like Symptoms: Persistent high fevers are risky for both mother and baby.
- Consistent, Painful Contractions Before 37 Weeks: May indicate preterm labor.
If you experience any of the above, seeking prompt medical attention is crucial. Early diagnosis and treatment can minimize risks for both you and your baby.
Diet & Nutrition in the Third Trimester
Many moms-to-be ask, “What to eat in third trimester pregnancy?” or “What is the best food for third trimester pregnancy?” This stage is all about fueling up for the final stretch while keeping a close eye on pregnancy weight gain and nutritional requirements.
- Lean Proteins: Chicken, fish (low in mercury), beans, lentils, tofu, and eggs provide essential amino acids.
- Fiber-Rich Foods: Whole grains, fruits, and vegetables can help combat constipation.
- Calcium & Vitamin D: Dairy products, fortified plant-based milks, leafy greens, and safe sun exposure support bone health (for both you and baby).
- Iron & Folate: Iron needs are high in the third trimester. Lean red meats, spinach, and iron-fortified cereals are helpful. Folate continues to be vital, so include leafy greens and beans in your diet.
- Healthy Fats: Avocado, nuts, seeds, and low-mercury fish like salmon provide important omega-3 fatty acids for baby’s brain development.
Additionally, staying hydrated is essential. The World Health Organization (WHO) suggests adequate fluid intake supports metabolic processes and reduces the risk of urinary tract infections. Keep a water bottle handy and sip throughout the day.
“Check our Pregnancy Nutrition Calculator to get diet guidance for a healthy pregnancy.”
Exercise & Fitness in the Third Trimester
Staying active can ease discomforts like pregnancy third trimester pelvic pain and help maintain a healthy weight.
Exercise During Pregnancy Third Trimester
Low-impact, moderate exercise is typically encouraged unless your doctor advises otherwise. Good options include:
- Walking: A simple way to improve circulation and manage weight.
- Pregnancy Yoga Third Trimester: Focuses on gentle stretching, relaxation, and pelvic floor strengthening.
- Swimming: Reduces pressure on joints and provides full-body conditioning.
- Prenatal Pilates: Builds core strength, which can help with labor and reduce back pain.
Pregnancy Exercises Third Trimester / Pregnancy Stretches Third Trimester
- Pelvic Tilts / Cat-Cow Stretches: Alleviate lower back tension.
- Hip Circles on a Birthing Ball: Open the hips and may help with pelvic pain.
- Leg & Ankle Stretches: Reduce cramps and swelling.
Always warm up and cool down, listen to your body, and avoid high-impact or contact sports. If you notice dizziness, vaginal bleeding, or contractions during exercise, stop and contact your healthcare provider.
Preparing for Labor & Delivery
With the upcoming due date, it’s natural to feel a mix of excitement and apprehension. Consider these tips to help you get ready:
- Hospital Bag: Pack essentials around Week 34 or 35, including clothes for you and the baby, toiletries, paperwork, and phone chargers.
- Birth Plan: Write down your preferences about pain management, labor positions, and who you want in the delivery room. Share it with your medical team.
- Prenatal Classes: Lamaze or other childbirth education classes can offer insights into labor techniques, breathing exercises, and postpartum care.
- Childproofing & Nursery Prep: Assembling furniture, organizing baby clothes, and stocking up on diapers can ease stress later.
- Perineal Massage: Some women find that gentle self-massage may help reduce tearing during delivery.
- Regular Check-Ups: Keep up with routine exams, including ultrasound in third trimester, blood pressure checks, and fetal monitoring. The Mayo Clinic stresses the importance of regular prenatal visits to track both maternal and fetal health.
FAQ
When is the Third Trimester of Pregnancy?
It usually begins at Week 28 and continues until Week 40 or birth.
What Week Does the Third Trimester Start in Pregnancy?
The third trimester starts the moment you hit Week 28.
How Many Weeks is the Third Trimester of Pregnancy?
The third trimester generally spans from Week 28 to Week 40 — that’s roughly 12 weeks, though some moms go beyond Week 40.
Is Lower Back Pain in the Third Trimester Common?
Yes, a growing uterus can shift your center of gravity, leading to backache. Regular stretching and supportive devices can help.
What if I Experience Spotting During the Third Trimester?
Light spotting may result from cervical irritation, but any heavy bleeding should be immediately evaluated by a doctor.
Should I Worry About Headaches in the Third Trimester?
Occasional headaches can happen. However, if headaches are severe or accompanied by blurred vision or high blood pressure, consult a healthcare professional right away.
Are There Any Recommended Pregnancy Exercises in the Third Trimester?
Low-impact workouts like walking, prenatal yoga, and swimming are generally considered safe. Always check with your doctor if you have specific conditions or risk factors.
What to Eat in the Third Trimester for Maximum Nutrition?
Focus on:
- Lean proteins
- Milk or dairy products (or fortified alternatives)
- Fiber-rich produce
- Whole grains
- Healthy fats like avocados or nuts
Iron and folate remain essential nutrients during this stage.
Why Do I Feel Pregnancy Insomnia in the Third Trimester?
Frequent restroom trips, anxiety about labor, and physical discomfort can disrupt sleep. Establish soothing bedtime routines and consider using extra pillows for support.
Is an Ultrasound in the Third Trimester Necessary?
Your provider might order one to measure the baby’s growth, position, and amniotic fluid levels, ensuring everything progresses smoothly.
Conclusion
The third trimester pregnancy is an exciting period of final preparations and emotional anticipation. Keeping track of common symptoms—like lower back pain pregnancy third trimester, pregnancy headaches third trimester, or pregnancy insomnia third trimester—helps you monitor your well-being and know when to consult your healthcare provider. Meanwhile, focusing on balanced diet in the third trimester of pregnancy, moderate exercise during pregnancy third trimester, and regular prenatal check-ups ensures you and your baby stay healthy.
Things move swiftly from Week 28 onward, so you’ll want to finalize your birth plan, complete your baby registry, and gather essentials for the hospital. Remember, every woman’s journey differs, so stay flexible even if your pregnancy or labor veers off your initial plan. Ultimately, informed preparation can ease anxieties and set you on a smoother, more confident path to welcoming your new family member.
References & Further Reading