The third trimester. You're in the home stretch, but it can feel like the longest part of the marathon. Your body is changing daily, and the list of discomforts seems to grow. While everyone focuses on what you should do—take your vitamins, go to appointments—knowing what to stop doing is arguably more crucial now. This isn't about fear-mongering. It's about smart, evidence-based adjustments to protect your well-being and your baby's as you prepare for birth.
Let's cut through the noise and old wives' tales. Based on current guidelines from sources like the American College of Obstetricians and Gynecologists and real-world experience, here’s your practical, no-nonsense guide to navigating the final weeks.
Your Quick Navigation Guide
Don't Make These Travel Plans
That babymoon to a remote island? The cross-country road trip to see family? Reconsider. In the third trimester, your travel risk profile changes dramatically.
Airlines have strict rules for a reason. Most won't let you fly after 36 weeks for a single pregnancy, and often after 32 weeks for multiples. They're worried about you going into labor at 35,000 feet. But even before that cutoff, think about it. Can you comfortably sit in a cramped seat for hours with swollen ankles and a bladder the size of a thimble? The risk of deep vein thrombosis (blood clots) is higher in pregnancy, and long periods of sitting compound it.
If you must travel, here’s the drill:
- Get clearance: A note from your doctor is often required by airlines after 28 weeks.
- Choose your seat wisely: Aisle seat, every time. You'll need to get up and walk every hour.
- Pack support: Compression socks are non-negotiable. So is a giant water bottle.
- Plan your destination: Are you going somewhere with easy access to a good hospital? This isn't the time for off-the-grid adventures.
Car trips need planning too. Limit driving to a few hours at a time. Stop every 90-120 minutes to walk, stretch, and use the bathroom. Wear your seatbelt with the lap portion under your belly, across your hips.
A Quick Reality Check
I learned this the hard way. At 32 weeks, I took a 3-hour car ride. We didn't stop. The Braxton Hicks contractions started an hour in and didn't let up until I was home, hydrated, and lying down. It was scary and completely preventable. Your body is telling you to slow down. Listen to it.
Don't Stick to Your Pre-Pregnancy Workout
If you've been active, fantastic. Keep it up—but modify aggressively. The goal now is maintenance and preparation, not personal bests.
Your center of gravity is off. Your ligaments are looser thanks to the hormone relaxin. This makes you more prone to falls and strains.
| Activity | Why to Avoid or Modify | Safer Alternative |
|---|---|---|
| Running/Jogging | High impact on joints, balance issues, pelvic floor pressure. | Brisk walking, elliptical machine, stationary bike. |
| Contact Sports | Obvious risk of abdominal impact. | Not advisable. Focus on non-contact activities. |
| Heavy Weightlifting | Risk of straining while holding breath (Valsalva maneuver), which spikes blood pressure. | Lighter weights with higher reps. Focus on form. |
| Exercises Lying Flat on Back | After 16-20 weeks, the uterus can compress the vena cava, reducing blood flow to you and baby. | Prop yourself up with pillows or use a wedge. Do exercises on your side or seated. |
| Hot Yoga or Hot Pilates | Risk of overheating and dehydration, which can be dangerous. | Regular temperature prenatal yoga or stretching. |
The subtle mistake here is ignoring your pelvic floor. Even if you're a fitness pro, you might be doing movements that create downward pressure. Focus on exercises that engage and lift the pelvic floor, like tailored prenatal yoga poses and gentle kegels, rather than ones that pound it.
Don't Get Casual About Your Diet
You might be tired of being careful, but the third trimester is when some risks actually increase. Your immune system is slightly altered, and baby is taking up so much room that your digestive system is sluggish.
Foodborne illness is a bigger deal now. Listeria, while rare, can have severe consequences. This means being vigilant about:
- Unpasteurized cheeses and juices: Check labels on soft cheeses like feta, brie, and blue cheese.
- Raw or undercooked meats, eggs, and fish: Sorry, that runny yolk and rare steak need to wait. Sushi from a reputable source is a debated topic—many OBs still say avoid it due to parasite/bacteria risk.
- Prepared salads from deli counters (like egg, chicken, or seafood salad) and unheated deli meats. If you crave a sandwich, heat the meat until steaming first.
- Excessive caffeine: Most guidelines say under 200mg daily (about one 12-oz coffee). But remember, it's in tea, soda, and chocolate too.
On the flip side, don't fall for "eating for two" in terms of calories. You only need about 300-500 extra calories per day in the third trimester. Focus on nutrient density: protein, iron, calcium, and healthy fats. A handful of nuts, Greek yogurt, or an extra serving of lean meat does more for you and baby than an extra bag of chips.
Don't Ignore Your Sleep Position
This is the big one that causes endless anxiety. The advice to sleep on your left side is everywhere. But let's be realistic. You will move in your sleep.
The core issue is avoiding the supine position—lying flat on your back. Research, including studies often referenced by the NIH, suggests that after about 20 weeks, the weight of your uterus can compress a major blood vessel called the inferior vena cava when you're on your back. This can reduce blood flow to your heart and, consequently, to your baby. It can also make you feel dizzy, nauseous, or short of breath.
So, what's the practical approach?
Start your sleep on your left side. This is optimal for circulation. Use pillows strategically: one between your knees (aligns hips), one behind your back to prevent rolling, and a wedge or small pillow under your belly for support. This creates a cozy "nest" that makes it physically harder to roll onto your back.
If you wake up on your right side or even on your back, don't panic. Your body likely woke you up if there was a problem. Gently roll back to your left side. The goal is to minimize time spent on your back, not to achieve perfection.
Don't Underestimate Stress and Overwhelm
It's easy to dismiss this as "soft" advice, but chronic stress in the third trimester can have real physical effects, including contributing to high blood pressure. Your to-do list is long: set up the nursery, prep for maternity leave, take childbirth classes.
Stop trying to do it all. Delegate. Say no. That nesting instinct is powerful, but scrubbing the bathroom floor at 34 weeks is not a good use of energy.
Here are a few concrete don'ts for your mental space:
- Don't spend hours on social media comparing your bump or your nursery to others. It's a trap.
- Don't ignore signs of anxiety or depression. Feeling persistently sad, angry, or detached is not just "hormones." Talk to your doctor.
- Don't skip all relaxation. Even 10 minutes of deep breathing, listening to a guided meditation, or taking a warm bath (not hot!) can reset your nervous system.
This is prep work, too. The ability to manage stress and ask for help is a crucial skill for parenthood.
Don't Skip or Delay Medical Advice
Your appointment schedule gets more frequent in the third trimester—every two weeks, then every week. It's tempting to skip one if you're feeling fine. Don't.
These visits check for silent but serious conditions like preeclampsia (checking your blood pressure and urine protein) and intrahepatic cholestasis of pregnancy (ICP, which causes intense itching). They monitor baby's growth and position.
More importantly, know the red flags that mean call your doctor immediately, don't wait for the next appointment:
- Severe headache that won't go away.
- Visual changes like seeing spots or flashes of light.
- Severe pain in your upper abdomen.
- Sudden, significant swelling in your face, hands, or feet.
- Vaginal bleeding or fluid leakage.
- A noticeable decrease in baby's movements. Don't just worry; do a kick count. If you don't feel 10 movements in 2 hours while focused, call.
Having a "better safe than sorry" mindset is essential. No question is too silly for your care team in these final weeks.
Putting It All Together
The third trimester is about fine-tuning. Listen to your body more intently than ever. The things you should avoid aren't meant to restrict your life but to channel your energy into the final, crucial phase of growing your baby and preparing for birth. It's okay to slow down. It's smart to be cautious. When in doubt, pick up the phone and call your provider. You've got this.