Week 33 of Pregnancy
Your baby is about the size of a jicama
Your Baby This Week
Development milestones for week 33
At 33 weeks pregnant, your baby is about 17.2 inches long and weighs roughly 4.2 pounds. The big focus now is lung development - the lungs are maturing rapidly and producing surfactant, a substance that helps the air sacs inflate and prevents them from collapsing after birth. This is a critical milestone because well-developed lungs significantly improve outcomes if your baby arrives early. Your baby's immune system is strengthening as antibodies pass from your bloodstream through the placenta. The bones in the skull remain soft and slightly separated, which allows them to overlap during delivery - this is why some babies are born with slightly cone-shaped heads that round out within days. Your baby is likely running out of room for big movements, so you might feel more squirming and rolling than the kicks you felt earlier. Sleep cycles are well established now.
Your Body This Week
Changes you may experience
The nesting instinct might be kicking into high gear. Suddenly you cannot stand the dust on your baseboards or the disorganized closet that never bothered you before. Research suggests nesting peaks in the third trimester, driven partly by hormonal changes including increased oxytocin. You might find yourself deep-cleaning the refrigerator at midnight or reorganizing the baby's dresser for the third time this week. Embrace it within reason, but avoid overexertion, climbing ladders, or using harsh chemical cleaners. Back pain is likely significant at this point - about two-thirds of pregnant women experience lower back or muscle pain in the third trimester. Your changing center of gravity and loosened ligaments contribute to this discomfort. Sleeping is becoming an engineering project involving multiple pillows. Many moms report that no position feels comfortable for more than an hour.
Tips & Advice for Week 33
Practical guidance from real moms
Channel that nesting energy productively. Install the car seat and have it inspected at your local fire station or hospital - studies show most car seats are installed incorrectly. Wash and organize baby clothes, but skip fabric softener on items that will touch your newborn's skin. Stock up on postpartum supplies for yourself: large pads, comfortable underwear, nipple cream if you plan to breastfeed, and stool softeners for post-delivery. For back pain relief, prenatal massage can work wonders. A warm compress on your lower back, prenatal yoga, and sleeping with a pillow between your knees all help. If nesting mania has you wanting to repaint the nursery, opt for low-VOC or zero-VOC paints and ensure excellent ventilation. Better yet, let someone else handle painting while you supervise from another room.
Medical Guidance for Week 33
What to discuss with your healthcare provider
Continue biweekly appointments and communicate any concerns. Your provider will discuss signs of preterm labor: contractions that come regularly and increase in intensity, unlike Braxton Hicks which are irregular and stop with position changes. If you experience period-like cramping, lower back pain, or increased vaginal discharge, call your provider. Begin discussing your birth plan and pain management preferences.
Disclaimer: For educational purposes only. Consult your healthcare provider for personalized medical advice.