Medical Disclaimer: This article is for informational purposes only. Always consult your healthcare provider.
At 27 weeks, you’ve reached the end of the second trimester! Your baby is about the size of a head of lettuce—roughly 14.5 inches long and weighing about 2 pounds. Next week marks the beginning of the third trimester, the final stretch before meeting your baby. Your baby’s brain is incredibly active, and sleep-wake cycles are well established.
Baby Development at 27 Weeks
Your baby is about 14.5 inches and weighs approximately 2 pounds. The brain is extremely active—brain tissue continues to develop, and your baby now has regular periods of sleep and wakefulness. You may notice periods of high activity followed by quieter times as your baby sleeps.
Your baby can now open and close their eyes, suck their thumb, and hiccup. The lungs, while not fully mature, continue developing. If born now, your baby would have an approximately 80-90% survival rate with NICU care. For more on the second trimester, see our second trimester guide.
Your Body This Week
You’ve completed the second trimester! Many women feel a mix of excitement and anxiety about the third trimester ahead. Weight gain is typically 17-24 pounds. Your belly is large enough that sleeping positions, bending, and tying shoes are becoming challenging.
Swelling may increase in your feet and ankles, especially at the end of the day or in warm weather. Your doctor will monitor for signs of preeclampsia (high blood pressure with protein in urine).
Common Symptoms at 27 Weeks
Symphysis pubis dysfunction (SPD): Pain at the front of the pelvis from loosened joints. Avoid wide leg movements and use a pillow between your knees at night.
Leg cramps: Especially common at night. Stretch calves before bed and stay hydrated.
Heartburn: Worsening as the uterus pushes on the stomach. Eat small meals, avoid triggers.
Anxiety about the third trimester: Completely normal. Talk to your partner, friends, or healthcare provider about your concerns.
What to Do This Week
Prepare for your third trimester. Prenatal visits will increase to every 2 weeks from week 28, then weekly from week 36.
Begin thinking about your hospital bag and what you’ll need for delivery.
Discuss Rh factor testing. If you’re Rh-negative, you’ll receive a RhoGAM shot around 28 weeks to prevent complications.
Continue exercising and staying active. For the third trimester, see our third trimester guide.
Nutrition Spotlight: Omega-3 for Brain Development
Your baby’s brain is developing rapidly. DHA (an omega-3 fatty acid) is critical. Eat 2-3 servings of low-mercury fish weekly (salmon, sardines), walnuts, flaxseeds, and chia seeds. Consider a DHA supplement if your prenatal doesn’t include it. Visit our nutrition guide.
When to Call Your Doctor
- Vaginal bleeding or fluid leaking
- Regular contractions before 37 weeks
- Severe headaches with vision changes
- Sudden swelling of face or hands
- Decreased fetal movement
- Signs of preterm labor
See our when to call your doctor guide.
Frequently Asked Questions
What changes in the third trimester?
Prenatal visits become more frequent, baby grows rapidly, and you’ll focus on birth preparation. Common symptoms include increased back pain, swelling, heartburn, and fatigue.
What is the RhoGAM shot?
If you’re Rh-negative, this injection around 28 weeks prevents your body from producing antibodies against your baby’s blood cells, which could cause complications in current or future pregnancies.
Is my baby’s survival rate good at 27 weeks?
Yes. At 27 weeks, survival rates with NICU care are approximately 80-90%, with outcomes improving each additional week of pregnancy.
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