27 Weeks Pregnant: End of the Second Trimester
Medically reviewed by
Maureen Kelly, RN — 20+ years in L&D, postpartum, NICU, and women’s health.
Reviewed against ACOG, AAP, and Mayo Clinic guidance. Meet Maureen →
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.
Get weekly pregnancy updates
Key takeaways for the second trimester
- Energy typically returns. Many people feel their best during the second trimester.
- The anatomy scan (around weeks 18–22) is a comprehensive ultrasound that checks fetal organ development and confirms placenta position.
- Quickening — first felt fetal movement — typically begins between weeks 16 and 22, earlier in subsequent pregnancies.
- Glucose screening for gestational diabetes is usually scheduled between weeks 24 and 28.
- By 24 weeks, viability is reached with intensive NICU support; by 28 weeks, survival rates exceed 90% in well-equipped centers.
When to call your provider
Call your OB-GYN, midwife, or labor and delivery unit right away if you experience:
- Heavy vaginal bleeding (more than light spotting)
- Severe abdominal or pelvic pain
- A severe headache that doesn’t respond to acetaminophen
- Sudden facial, hand, or leg swelling
- Vision changes (spots, blurring, light sensitivity)
- Decreased fetal movement after 28 weeks (fewer than 10 movements in 2 hours during baby’s active period)
- Signs of preterm labor: regular contractions, pelvic pressure, low back pain, fluid leaking
- Fever over 100.4°F (38°C)
When in doubt, call. Your provider would always rather hear from you about a non-issue than miss something important.
Frequently asked questions about week 27
How big is the baby at 27 weeks pregnant?
At 27 weeks, your baby is roughly the size of a head of lettuce (~14.4 inches, 1.9 lb). Size estimates vary from baby to baby and are based on standardized growth charts (ACOG, NICHD).
What symptoms are common at 27 weeks pregnant?
Common second-trimester symptoms include round ligament pain (sharp pulls in the lower belly), nasal congestion, mild leg cramps, increased appetite, and the first felt fetal movements. Many people report feeling their best in this trimester.
What prenatal appointments happen around 27 weeks?
The glucose challenge test for gestational diabetes is typically performed between weeks 24 and 28.
When should I worry at 27 weeks pregnant?
Decreased fetal movement after you have started feeling consistent kicks, severe headache, vision changes, sudden swelling, severe abdominal pain, vaginal bleeding, leaking fluid, or signs of preterm labor (regular contractions before 37 weeks) warrant immediate evaluation.
Is what I’m feeling at 27 weeks normal?
Most of the symptoms experienced at 27 weeks are part of typical pregnancy and reflect your body’s adjustments. If anything feels alarming, severe, or unusual for you, contact your provider — trust your instincts.
Sources
- American College of Obstetricians and Gynecologists (ACOG). Your Pregnancy and Childbirth: Month to Month (current edition). acog.org
- American Academy of Pediatrics. Caring for Your Baby and Young Child (current edition).
- Mayo Clinic. Pregnancy week by week. mayoclinic.org
- National Institute of Child Health and Human Development (NICHD). Pregnancy and Pregnancy Loss research and guidance.