At 33 weeks, antibodies (especially immunoglobulin G) pass from you to baby through the placenta and help protect them after birth. Ask your OB-GYN or midwife which vaccines are recommended for you during pregnancy.
33 weeks pregnant is about 7.5 months. You are in month 8 of pregnancy and the third trimester.
Your baby at 33 weeks
Baby is about the size of a cantaloupe
33 weeks: how protection works
At 33 weeks, baby's immune system is still developing, but baby is already receiving antibodies from you. Immunoglobulin G crosses the placenta especially actively in the third trimester and helps protect the newborn in the first months after birth.
What usually happens this week
- Antibodies keep crossing the placenta to baby.
- The lungs and body fat continue to develop. Body fat helps baby stay warm after birth.
- Baby's sleep and wake cycles are becoming more regular.
- Growth continues steadily.
- Many providers recommend certain vaccines during pregnancy, such as Tdap (whooping cough) and, in fall and winter, the RSV vaccine. Your OB-GYN or midwife can tell you which ones fit your situation.
The cantaloupe comparison gives a sense of baby's size. The antibody transfer shows that baby is being prepared for life outside the womb. If you have questions about vaccines or protection for baby, bring them to your next prenatal visit.
Your body at 33 weeks
When to Call Your Provider
Swelling: When It Is Usually Normal
At 33 weeks (about 8 months), many people notice some swelling in their feet and ankles. This is commonly caused by increased blood volume and pressure from the growing uterus on the veins in the pelvis and legs. Many people find that resting with their legs raised helps. Ask your provider if you are unsure whether your swelling is typical for you.
What Is Preeclampsia?
Preeclampsia is a pregnancy condition marked by high blood pressure that begins after 20 weeks of pregnancy. It can affect organs such as the kidneys and liver, and it can be serious for both the pregnant person and the baby.
Warning Signs: When to Get Help
- Blood pressure of 140/90 mmHg or higher on two readings taken at least 4 hours apart. A reading of 160/110 mmHg or higher needs same-day emergency care.
- Severe headache that does not improve with rest or medicine.
- Vision changes, such as blurriness, flashing lights, or seeing spots.
- Sudden swelling in your face, hands, or fingers.
- Severe pain in the upper belly (under your ribs).
- Nausea or vomiting that starts suddenly or gets worse, or trouble breathing.
Common symptoms at 33 weeks
Mild swelling in the feet and ankles is common, especially later in the day. Resting with your feet raised and drinking water can help, but sudden or face and hand swelling should be reported.
Your growing baby presses on your stomach, which can cause burning after meals. Smaller meals, staying upright after eating, and avoiding late snacks often help.
As the baby takes up more room, your lungs may feel less spacious. Slowing down, changing position, and taking breaks can make breathing feel easier.
Extra weight and shifts in posture can strain your lower back. A supportive pillow for sleep, good shoes, and gentle stretching may bring some relief.
The baby's head may press on your bladder again as they settle lower. Emptying your bladder fully when you can is helpful, and let your provider know if urinating hurts.
Finding a comfortable position can take effort at this stage. Many people find that lying on their left side with a pillow between their knees feels best.
Your week 33 checklist
Tests and appointments
- Tdap vaccine. Tdap is usually offered between 27 and 36 weeks to help protect your baby from whooping cough after birth.
- RSV vaccine. If it is RSV season, your provider may offer an RSV vaccine between 32 and 36 weeks to help protect your baby from this virus.
Questions about week 33
How many months is 33 weeks pregnant?
33 weeks pregnant is about 7.5 months. You are in month 8 of pregnancy and the third trimester.
What trimester is 33 weeks?
Week 33 is in the third trimester. The first trimester runs through week 13, the second from week 14 to 27 and the third from week 28 until birth.
What is happening with the baby at 33 weeks?
At 33 weeks, antibodies (especially immunoglobulin G) pass from you to baby through the placenta and help protect them after birth. Ask your OB-GYN or midwife which vaccines are recommended for you during pregnancy.
Is swelling in my feet at 33 weeks normal?
Mild swelling in the feet and ankles is common and often normal. Call your provider if the swelling is sudden, affects your face or hands, or comes with headache, vision changes, or upper belly pain. These can be signs of preeclampsia and need prompt care.
When should I pack my hospital bag?
Many people pack their bag around this time so it is ready if labor starts early. Include comfortable clothing, toiletries, phone charger, and important papers. Ask your provider or hospital what they recommend bringing.
Which vaccines should I get during pregnancy?
Your provider can tell you which vaccines are recommended for you. Tdap and RSV are often discussed around this time. Vaccines during pregnancy help pass protective antibodies to your baby.
Safe or not?
Guides for this stage
Learn more
- NIH: Pregnancy (NICHD)
- CDC: Pregnancy
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