Week 37 of Pregnancy
Learn about your baby's development and what to expect at 37 weeks pregnant.
Baby's Size This Week
Baby Development at Week 37
- ● At week 37, your baby is about 48.6 cm long and weighs around 2859g — classified as early term (not yet full term, which begins at 39 weeks).
- ● The lungs are fully mature with abundant surfactant, making breathing after birth reliable and independent.
- ● Your baby is positioned head-down and deeply engaged in the pelvis, with the head pressing against the cervix in preparation for labor.
- ● The immune system continues receiving maternal antibodies across the placenta — breastfeeding after birth will further boost passive immunity.
- ● The brain and nervous system are still maturing — neural development continues actively until at least 2 years of age postnatally.
- ● Your baby now has a firm grasp reflex and can open and close fists, a reflex that will be tested by your pediatrician in the first newborn exam.
Your Body at Week 37
- ● As week 37 approaches, you may notice increased pelvic pressure and lower back pain as the baby descends further into the pelvis.
- ● Nesting instincts often kick in strongly — a sudden burst of energy and an urge to prepare everything is common.
- ● Cervical changes are actively occurring — effacement (thinning) and dilation (opening) are monitored at weekly visits.
- ● Braxton Hicks contractions are intensifying and may be accompanied by mild cramping — track frequency carefully.
- ● The mucus plug may fully dislodge, appearing as increased vaginal discharge that may be tinged with blood (bloody show).
- ● You may feel sharper pelvic floor pressure and a sensation that the baby could fall out — this is normal as engagement deepens, though it can be uncomfortable.
Week 37 Checklist
- ☐ Attend your weekly prenatal appointment and ask your provider about your cervical progress (effacement and dilation).
- ☐ Ensure your hospital bag is packed, in the car, and your partner or support person knows where it is.
- ☐ Confirm that your infant car seat is installed and has been checked by a certified car seat technician.
- ☐ Finalize your birth plan and ensure a copy is in your hospital bag and on file with your care team.
- ☐ Install key newborn care apps (feeding tracker, diaper log) and ensure your phone is charged and ready.
- ☐ Confirm your postpartum support network: who will help the first week, meal deliveries scheduled, and lactation consultant contact saved.
Frequently Asked Questions
What should I expect at 37 weeks pregnant?
At 37 weeks pregnant, you are classified as early term (full term begins at 39 weeks). Your baby is about the size of a Winter melon (48.6 cm) and has mature lungs and established reflexes. Common symptoms include intense pelvic pressure, nesting urge, Braxton Hicks contractions, bloody show, and cervical changes. Always consult your healthcare provider for personalized guidance.
How big is my baby at 37 weeks?
At week 37, your baby is approximately 48.6 cm in length and weighs around 2859g — roughly the size of a Winter melon. These measurements are averages based on WHO fetal growth charts; individual babies vary naturally in size.
Is 37 weeks considered full term?
No. ACOG updated its terminology in 2013: full term is defined as 39 weeks 0 days through 40 weeks 6 days. Week 37 is classified as early term (37–38 weeks 6 days). While babies born at 37 weeks have a high survival rate, they have a higher risk of NICU admission, feeding difficulties, jaundice, and respiratory issues compared to babies born at 39–40 weeks. Elective deliveries before 39 weeks without medical indication are generally not recommended.
What is bloody show and does it mean labor is starting?
Bloody show is the passage of mucus tinged with blood as the cervix dilates and small blood vessels rupture. It is a normal sign that the cervix is ripening and that labor may begin within hours to a few days. It is different from the mucus plug (which can be clear or slightly pink). Contact your provider if you experience heavy bright-red bleeding, which could signal a more serious condition such as placental abruption.
How do I know if my water has broken at 37 weeks?
Water breaking (rupture of membranes) can feel like a sudden gush or a slow, steady trickle of clear or slightly yellowish fluid from the vagina — it will not stop with tightening pelvic muscles, distinguishing it from urine leakage. If you think your water has broken at 37 weeks, contact your provider or go to your birth facility immediately. Even without contractions, ruptured membranes require assessment to rule out infection and determine the plan for delivery.
Track Your Exact Pregnancy Week
Use our free Pregnancy Week Tracker to find out exactly how far along you are based on your last menstrual period or due date.
Track My Pregnancy →Sources
- ACOG
- WHO Fetal Growth Charts
- Mayo Clinic
Medical disclaimer: This content is for informational purposes only and is not intended as medical advice. Always consult a qualified healthcare provider for guidance specific to your pregnancy.