33 Weeks Pregnant: Baby’s Bones Are Hardening

Welcome to 33 weeks pregnant—you’re now solidly in the final 7 weeks of pregnancy. Your baby is becoming increasingly viable should they arrive unexpectedly, and your body is in the full swing of third-trimester changes. You might be experiencing the full gamut of late pregnancy discomforts: sleep difficulties, physical aches, and heightened emotions as you prepare mentally and practically for your baby’s arrival. This week is an excellent time to focus on self-care, birth preparation, and strengthening your support system as you approach labor and delivery.

Baby Development at 33 Weeks

Your baby is about the size of a pineapple this week—approximately 17-18 inches long and weighing roughly 4.5-5 pounds. Your baby is adding about a pound per week at this point, with much of that weight going toward muscle and organ maturation.

Your baby’s brain is undergoing rapid development. The cerebral cortex is becoming increasingly convoluted, with deeper grooves and more organized structures. Neural pathways are being formed at an incredible rate. Your baby is capable of more complex processing, memory formation, and learning now than earlier in pregnancy. Some research suggests that babies can respond to external stimuli and begin learning about their environment while still in utero.

Your baby’s pupils can now dilate and constrict in response to light. Your baby’s ears are fully developed, and they can hear not only your voice and heartbeat but also external sounds from outside the womb. This is why many providers recommend talking to your baby and playing music during the third trimester—your baby is definitely listening.

At 33 weeks, your baby’s blood cell production is now happening primarily in the bone marrow. Your baby’s immune system continues to mature, with white blood cells becoming more specialized. Most antibodies are being transferred from your body through the placenta. Your baby’s toenails and fingernails are fully grown and may be quite long at birth.

Your Body This Week

At 33 weeks, you’ve likely gained 22-28 pounds. Your uterus is now about 5.3 inches above your belly button. Many women describe feeling like they’ve reached maximum capacity at this point—the physical sensation of carrying such weight is increasingly challenging.

Your skin continues to stretch to accommodate your baby. Some women develop red stretch marks at this stage. While there’s limited evidence that creams prevent stretch marks, keeping your skin moisturized and maintaining healthy weight gain can help. Stretch marks fade significantly after delivery, becoming pale or silver-toned within months.

By 33 weeks, many women experience “pregnancy brain”—difficulty concentrating, forgetfulness, and mental fuzziness. This is real and has multiple causes: sleep deprivation, hormonal changes, and the enormous physical demands of late pregnancy. Making lists and using reminders can help.

Emotionally, many women experience a mix of excitement, anxiety, and anticipation. Some become more emotional or sensitive, crying more easily. Others feel increasingly grounded and focused as they approach labor. Both are normal. You may also notice that your navel has become completely flat or even popped out due to uterine pressure. This returns to normal after pregnancy.

Common Symptoms at 33 Weeks

Difficulty Sleeping: Finding a comfortable sleeping position is increasingly challenging. Using a full-body pregnancy pillow that supports your belly, back, and knees can help. Left-side sleeping is optimal for blood flow to the placenta.

Nighttime Leg Cramps: Many women experience painful leg cramps at night. Stretching your calves before bed, staying well-hydrated, and magnesium supplementation (discuss with your provider) can help prevent cramps.

Braxton-Hicks Contractions: Practice contractions typically become more frequent and noticeable. You might experience several per hour, particularly in the evening or after activity. If you experience more than 4-6 per hour, or if contractions become painful and regular, contact your healthcare provider.

Increased Urinary Frequency: Your baby is pressing increasingly on your bladder. Continue drinking adequate water but try to time most fluid intake before 6 PM to reduce nighttime bathroom trips.

Hemorrhoids: Constipation and increased pressure on rectal blood vessels often lead to hemorrhoids. Staying well-hydrated, eating fiber-rich foods, using provider-approved stool softeners, and taking warm baths can help.

Feeling More Emotional: Hormonal changes, sleep deprivation, and anxiety about approaching labor can intensify emotions. Talk about your feelings with your partner, friends, or a therapist.

What to Do This Week

Pack Your Hospital Bag: Your bag should now be fully packed and easily accessible. Aim to have it ready by 34 weeks in case your baby arrives early.

Arrange Childcare for Older Children: If applicable, finalize arrangements for their care during your hospital stay. Make sure all caregivers have the necessary information.

Practice Labor Comfort Techniques: Whether planning an unmedicated birth or planning to use pain medications, practicing relaxation techniques is valuable. These might include controlled breathing, visualization, progressive muscle relaxation, or mantras.

Attend Prenatal Appointments: At 33 weeks, you should be having appointments every 2 weeks, increasing to weekly starting at 36 weeks. Don’t skip these—they’re crucial for identifying potential complications early.

Install Your Infant Car Seat: By 33-34 weeks, your infant car seat should be installed. Many hospitals won’t discharge you without proof of a properly installed car seat. Consider getting your seat inspected by a certified technician.

Stay Active: Continue with pregnancy-safe exercises to help manage discomfort and prepare for labor.

Nutrition Spotlight: Omega-3 Fatty Acids

Omega-3 fatty acids, particularly DHA and EPA, are crucial for your baby’s brain and eye development, especially during the third trimester. Your baby’s brain is accumulating DHA at a particularly rapid rate during these final weeks. Studies show that adequate DHA intake during pregnancy is associated with better cognitive development and visual acuity in infancy.

The recommended intake of DHA during pregnancy is 200-300 mg per day. The richest dietary sources are fatty fish: salmon, mackerel, sardines, anchovies, and herring. Due to mercury concerns, the FDA recommends limiting high-mercury fish. Safe fish choices include: salmon, sardines, and canned light tuna (limit to 6 oz per week). Review our guide on foods to avoid during pregnancy.

Plant-based omega-3 sources (ALA) include: walnuts, flaxseeds, chia seeds, hemp seeds, and plant oils. These are less efficient at providing DHA than fish sources. If you don’t consume fish regularly, discuss DHA supplementation with your healthcare provider.

When to Call Your Doctor

Contact your healthcare provider immediately if you experience:

• More than 4-6 Braxton-Hicks contractions per hour, or contractions that become painful and regular
• Gushing or continuous leaking of fluid from your vagina
• Vaginal bleeding more than light spotting
• Severe abdominal pain that doesn’t improve with rest
• Sudden severe swelling in your face or hands, particularly with headache or vision changes
• Significant decrease in fetal movement
• Fever above 100.4°F (38°C)
• Difficulty breathing or chest pain

Frequently Asked Questions at 33 Weeks

What is the difference between true labor and Braxton-Hicks contractions?

Braxton-Hicks contractions are irregular, don’t progress in intensity or frequency, and don’t dilate your cervix. True labor contractions are regular, progressively stronger, closer together, and accompanied by cervical dilation. Many providers recommend coming to the hospital when contractions are about 5 minutes apart for about an hour.

Is it normal to feel anxious about labor at 33 weeks?

Absolutely. Most pregnant women experience some anxiety about labor as it approaches. Taking childbirth classes, practicing relaxation techniques, and discussing fears with your partner or counselor can all help address labor anxiety.

Should I be concerned if my baby seems less active at 33 weeks?

Some decrease in movement patterns is normal as your baby grows larger and has less room. However, you should still feel your baby move regularly throughout the day. If you notice a significant decrease from your baby’s normal pattern, contact your healthcare provider.

What should I do to prepare for breastfeeding before baby arrives?

Attending a breastfeeding class before delivery is highly beneficial. Make sure your partner or support person understands that you’ll need support during early breastfeeding. Some women benefit from consulting with a lactation specialist during pregnancy.