Watch our video guide to Week 39 of your pregnancy journey:
What's Happening in Week 39?
Your baby weighs approximately 3.2-3.6kg and measures about 50-51cm from head to toe — roughly the length of a small watermelon. At 39 weeks, your baby is considered full term and is fully ready for life outside the womb.
Final developments are underway:
- Lung maturity: the lungs are now fully mature, producing sufficient surfactant — the substance that keeps the tiny air sacs open and functioning. This is one of the last organ systems to reach full maturity
- Brain development: the brain has been growing rapidly throughout the third trimester and now weighs about 30% more than it did at 35 weeks. Development will continue well after birth
- Immune system: your baby continues to receive antibodies through the placenta. These maternal antibodies will provide protection against illness during the first few months of life until your baby's own immune system strengthens
- Vernix and lanugo: the last of the waxy vernix coating and fine lanugo hair has mostly shed. Any remaining vernix will help lubricate the birth canal during delivery
- Fat stores: your baby has accumulated enough fat to maintain body temperature after birth. Those rounded cheeks and plump limbs are ready for their debut
Your baby's movements may feel different now — less dramatic kicks and more rolling, shifting, and pushing against your ribs or pelvis. The limited space means movement patterns change, but the frequency should remain consistent. Always contact your hospital if you notice a decrease in movements.
Your Body This Week
The final days of pregnancy can feel like the longest:
- Intense pelvic pressure: your baby's head is likely engaged deep in your pelvis, creating significant pressure on your bladder, rectum, and pelvic floor
- Braxton Hicks contractions: may become more frequent and intense, sometimes making you wonder if labour has started. True contractions follow a regular pattern and don't stop when you change position
- Cervical changes: your cervix is softening, thinning (effacing), and may begin to dilate. You might lose your mucus plug — a thick, sometimes blood-tinged discharge. This can happen days or even weeks before labour begins
- Nesting instinct: many women experience a sudden burst of energy and an overwhelming urge to clean, organise, and prepare the home
- Difficulty sleeping: between bathroom trips, heartburn, and finding a comfortable position, sleep can be elusive. Rest when you can during the day
- Emotional intensity: excitement, anxiety, impatience, and anticipation are all completely normal
Recognising Labour
Understanding the difference between pre-labour and active labour is important:
Early Signs (Labour May Be Approaching)
- Loss of mucus plug (a "bloody show")
- Increased vaginal discharge
- Loose bowel movements
- Mild, irregular contractions
- A general feeling of restlessness
Signs That Labour Has Started
- Regular contractions that become progressively longer, stronger, and closer together. Time them — when they're consistently 5 minutes apart, lasting 60 seconds each, for at least 1 hour, contact your hospital
- Waters breaking: a gush or a steady trickle of clear (sometimes slightly pink) fluid. Note the time and colour, and contact your hospital regardless of whether contractions have started
- Persistent lower back pain that comes and goes in waves
When to Go to Hospital Immediately
- Waters breaking with green or brown-tinged fluid (may indicate meconium)
- Heavy vaginal bleeding
- Decreased or absent baby movements
- Severe headache or visual disturbances
- Feeling unwell or feverish
Making the Most of These Final Days
- Rest as much as possible — you'll need your energy for labour and the first days with your newborn
- Spend quality time with your partner — life is about to change in the most wonderful way
- Double-check your hospital bag — make sure it's easily accessible with everything you need
- Keep your phone charged and ensure someone can drive you to hospital at short notice
- Eat well and stay hydrated — your body needs fuel for the work ahead
- Try to stay calm — your body has been preparing for this moment for 39 weeks. Trust the process
If You Go Past Your Due Date
Only about 5% of babies arrive on their exact due date. Going past 39 weeks is completely normal. Your maternity team will monitor you with additional appointments and may discuss induction if you reach 41-42 weeks. Every pregnancy is different, and your baby will arrive when they're ready.
This article is for general information purposes only and is not intended as medical advice. Every pregnancy is different. Always consult your GP, midwife, or healthcare provider for guidance specific to your circumstances.
Best wishes from all the team at Ultrasound Ireland. We've loved being part of your pregnancy journey.