Pregnancy Week 34: What to Expect — Baby Size, Symptoms & Tips

Six weeks until your due date, and your baby is doing some of the most important work of the entire pregnancy. The lungs are maturing rapidly — and this is the development that matters most between now and birth. Babies born at 34 weeks do well in most cases, but the lung work happening right now is what makes 37–40 weeks so much safer. Your job this week is to keep going, rest as much as you can, and pay attention to how you feel.

Track your progress with our Due Date Calculator.

Key Takeaways

• Your baby weighs about 2.1 kg (cantaloupe-sized) and measures roughly 45 cm from head to toe
• Surfactant production is ramping up rapidly — the critical factor for breathing independently after birth
• Most babies are head-down (vertex) by 34 weeks; the sucking reflex is becoming more efficient for feeding
• Common symptoms: pelvic girdle pain, swelling, sleep disruption, stronger Braxton Hicks, colostrum leaking
• Action items: start packing your hospital bag, finalize your birth preferences, and learn preterm labor signs

Your Baby This Week

Size: Cantaloupe — about 45 cm (head to toe)

Weight: About 2.1 kilograms

Growth is consistent and impressive right now. Key developments this week:

• Lungs are maturing. The production of surfactant — the substance that prevents the tiny air sacs (alveoli) in the lungs from collapsing after each breath — is ramping up significantly. This is the critical factor in whether a preterm baby can breathe independently. A 34-weeker has a good chance of breathing without major intervention; a 37-weeker has a dramatically higher chance.
• Fat is filling in fast. The layer of white fat under the skin is thickening, making your baby look increasingly like a newborn. This fat is essential for temperature regulation after birth and for energy reserves in the first days before your milk supply is established.
• Central nervous system is maturing. Reflexes are becoming more coordinated, and the baby is practicing swallowing, blinking, and responding to sensory input. The sucking reflex — essential for feeding — is getting more efficient this week.
• Head position. Most babies have turned head-down by 34 weeks (a position called vertex). If yours hasn't, your provider will discuss this and monitor it over the coming weeks.
• Vernix is thickening. The waxy coating that protects the skin in amniotic fluid is more substantial now. You'll likely see traces of it on your baby at birth, particularly in skin folds.
• Sleep-wake cycles. Your baby has identifiable sleep and awake periods. You may notice they're more active at certain times of day — often when you're trying to rest.

Your Body This Week

You may be feeling like your body has run out of room. That's because it largely has:

• Pelvic girdle pain. The hormone relaxin loosens the ligaments around the pelvis in preparation for birth. This is useful during labor, but in the weeks leading up to it, it can cause significant pain in the pubic symphysis, SI joints, and hips. A pelvic support belt, physiotherapy, and modified movement patterns can all help.
• Swelling. Edema in the feet, ankles, and lower legs is common and normal. It tends to be worse at the end of the day and in hot weather. Putting your feet up, wearing compression socks, and walking regularly all help manage it.
• Sleep disruption. Discomfort, frequent urination, leg cramps, and anxious thoughts all contribute. A pregnancy pillow, consistent sleep positioning, and a calming wind-down routine help more than most people expect.
• Braxton Hicks contractions. These are becoming more frequent and can feel more intense. They remain irregular and resolve with movement or hydration. If they become regular or painful, contact your provider.
• Colostrum leaking. Some women begin leaking small amounts of colostrum from the nipples at this stage. This is completely normal and not a sign that anything is wrong. Breast pads can help if it's noticeable through clothing.

Tips for Week 34

1. Pack your hospital bag — seriously, start now. Most people say they'll do it "next week" until they're 39 weeks and scrambling. The list is longer than you think. Essentials: your medical records and birth preferences, ID, comfortable loose clothing for labor, postpartum care items (maternity pads, comfortable underwear), newborn clothes and a car seat, phone charger, snacks.

2. Finalize your birth preferences document. This doesn't need to be long. A single page covering your preferences for pain management, labor support, cord cutting, immediate skin-to-skin, and feeding intentions is enough. Share it with your support person and bring a copy for the hospital.

3. Know the signs of preterm labor. Regular contractions (more than 4 in an hour), pelvic pressure that increases, significant low back pain that comes and goes, or a change in vaginal discharge (watery, mucus-y, or bloody) — any of these warrant a call to your provider before 37 weeks.

4. Look into your feeding plan. Whether you plan to breastfeed, formula-feed, or both, having some information before birth makes the early days easier. Lactation consultants, breastfeeding classes, and information on formula preparation are all worth exploring now if you haven't already.

5. Don't skip meals. Your baby is putting on about 30–35 grams per day. Adequate nutrition matters, and skipping meals when you're too tired or too uncomfortable to eat properly affects both your energy and your baby's growth.

When to Call Your Doctor

• Regular contractions before 37 weeks — even if they're not painful, regular contractions (4+ per hour) need to be evaluated
• Pelvic pressure or heaviness that comes on suddenly and feels different from usual discomfort
• Fluid leaking — any continuous leaking or gush of fluid, even if you're not sure what it is, requires same-day evaluation
• Decreased fetal movement — fewer than 10 movements in 2 hours warrants a call
• Severe or sudden swelling of the face, hands, or feet, or swelling accompanied by headache or visual changes
• Signs of preeclampsia (severe headache, upper right abdominal pain, visual disturbances)

Related Tools & Articles

• Due Date Calculator — Calculate your estimated due date
• Contraction Timer — practice using it now
• Hospital Bag Checklist — full packing list
• Pregnancy Week 35 — what's coming next
• Pregnancy Week-by-Week Overview — full timeline

Frequently Asked Questions

What happens if my baby is born at 34 weeks? A baby born at 34 weeks is considered "late preterm" and will likely need NICU support — primarily for breathing assistance, feeding, and temperature regulation. Most 34-weekers do very well, but they have measurably higher complication rates than babies born at 37–40 weeks. The lung development happening right now is what makes staying in so important.

My baby hasn't turned head-down at 34 weeks — what are my options? There's still time for the baby to turn. Most providers begin closely monitoring position from 36 weeks. If the baby remains breech closer to your due date, your options include external cephalic version (ECV) — a procedure where a provider manually attempts to turn the baby from outside — or a planned cesarean delivery.

What is pelvic girdle pain and how can I manage it? Pelvic girdle pain is caused by the hormone relaxin loosening the ligaments around the pelvis in preparation for birth. It causes discomfort in the pubic symphysis, sacroiliac joints, and hips. Management includes a pelvic support belt, physiotherapy, avoiding asymmetric movements (like standing on one leg), and modified activity. It resolves after birth.

What should I include in a birth preferences document? Keep it to one page. Cover: your pain management preferences, who you want in the room, your wishes for immediate skin-to-skin contact, delayed cord clamping preferences, feeding intentions (breastfeeding, formula, or both), and your priorities if a cesarean becomes necessary. Share it with your provider and your birth partner.

How do I know if I'm leaking amniotic fluid or just vaginal discharge? Amniotic fluid is typically clear or pale yellow, odorless, and flows continuously — it doesn't stop the way urine does when you tighten your pelvic floor. Vaginal discharge (leukorrhea) is milky and mucus-like. If you're unsure whether what you're experiencing is amniotic fluid, call your provider and go in for evaluation the same day.

Sources

• ACOG — Preterm Labor and Birth
• Mayo Clinic — Fetal Development: The Third Trimester
• ACOG — Preeclampsia and High Blood Pressure During Pregnancy
• Stanford Children's Health — Premature Baby Overview

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