Week 39
Your baby is the size of a small watermelon
What's happening this week
Your baby is now full term — the milestone that means every organ system is considered mature enough for life outside the womb. Your baby is approximately 20 inches long and weighs around 7 to 7.5 pounds, though healthy babies come in a wide range of sizes.
The lungs are fully mature, producing ample surfactant to support independent breathing. The brain has been rapidly adding mass in these final weeks and is now ready to manage the complex demands of life outside — regulating breathing, temperature, feeding, and the thousands of new sensory experiences your baby will encounter at birth.
Fat is still being added, particularly around the chest and shoulders. This fat will help your baby maintain body temperature in the first hours and days after birth. The liver has been storing iron, which will sustain your baby for the first several months until they begin eating iron-rich foods.
Your baby's immune system has received a final transfer of antibodies from you through the placenta, providing temporary protection against many of the infections you're immune to. This passive immunity will bridge the gap until your baby's own immune system matures and begins responding to vaccines.
Inside the womb, your baby is practicing all the skills they'll need: breathing (using amniotic fluid), sucking (on their thumb or fingers), swallowing, grasping, and even blinking. When the time comes, your baby is ready.
The question now is simple: when. Only about 5% of babies arrive on their exact due date. The normal window for delivery is 37-42 weeks, with most babies arriving between 39 and 41 weeks. Your baby will come when they're ready — and so will you.
Your body this week
One week until your due date. You are, in every sense, ready. Your body has been building, growing, and adapting for nine months, and it has done an extraordinary job.
You may notice increased signs that labor is approaching: more frequent and stronger Braxton Hicks contractions, increased pelvic pressure, loose stools, the loss of your mucus plug (if it hasn't happened already), and a general feeling of restlessness. Some people experience a burst of energy — the 'nesting surge' — in the day or two before labor begins.
Your cervix is likely changing: softening, thinning (effacing), and possibly beginning to dilate. Your provider is checking these changes at weekly visits. Remember: cervical progress doesn't predict exactly when labor will start, but it shows that your body is preparing.
The waiting game at 39 weeks is emotionally intense. Every twinge makes you wonder 'is this it?' Every night you go to bed wondering if tonight is the night. The anticipation can be exhausting. Try to stay occupied without overexerting yourself — short walks, low-key social plans, and simple projects can help pass the time.
If your provider has discussed a scheduled induction or cesarean, it may be planned for this week or next. ACOG considers 39 weeks the earliest appropriate time for elective delivery. The decision to induce versus wait for spontaneous labor depends on your individual circumstances, and your provider will guide you.
One last thing: you have done something remarkable. Growing a human from a single cell to a 7-pound baby is genuinely extraordinary, and you've done it while working, sleeping poorly, and handling everything else life has thrown at you. Be proud of yourself.
For dads
One week to the due date. You may feel like you've been holding your breath for nine months, and in a way, you have. The baby could come today, next week, or not for another three weeks — and the uncertainty is maddening. But here's the thing: you're as ready as you're going to get. The bags are packed, the car seat is installed, the nursery is ready. Now you wait. Use this week to take care of yourself. Get a haircut. Eat a good meal. Sleep. See a friend. Because once the baby arrives, your world changes fundamentally and permanently. That's a beautiful thing — but it's also worth savoring these final days of life before parenthood.
When labor starts, your role is clear: be calm, be present, and be her advocate. Know the birth plan. Know what she wants. And be prepared to adapt when things don't go as planned — because they often don't, and that's okay. During labor, the most important things you can do are: keep her hydrated (ice chips, water), help her change positions, apply counter-pressure to her lower back if she's in pain, keep the room calm, communicate with the medical team, and remind her she's doing an incredible job. You don't need to be a medical expert. You need to be her person.
Common concerns
Will my baby come on the due date?+
Probably not — only about 5% of babies are born on their exact due date. The due date is an estimate, not a deadline. Most babies arrive within a week or two of the due date — anywhere from 39 to 41 weeks is completely normal. First-time parents are slightly more likely to go past their due date. If you go past 40 weeks, your provider will increase monitoring and discuss options.
What are the stages of labor?+
Labor has three stages. Stage 1 is the longest: the cervix dilates from 0 to 10 centimeters. It includes early labor (0-6 cm, which can last hours to days), active labor (6-10 cm, faster and more intense), and transition (the final stretch to 10 cm, the most intense but shortest phase). Stage 2 is pushing and delivery — from full dilation to your baby's birth. Stage 3 is delivery of the placenta, which happens within 5-30 minutes after birth. Your provider and nurses will guide you through each stage.
What happens if I go past my due date?+
Going past your due date is common and usually not a cause for alarm. Your provider will increase monitoring — typically with non-stress tests and amniotic fluid checks — to ensure your baby is doing well. Most providers recommend induction between 41 and 42 weeks, as the risk of complications increases slightly after that point. The specific timing depends on your individual situation and your provider's assessment.
How will I know when to go to the hospital?+
The classic guideline is the 5-1-1 rule: contractions 5 minutes apart, lasting 1 minute each, for at least 1 hour. Also go if your water breaks, you have heavy vaginal bleeding, or you notice significantly decreased fetal movement. If this is your first baby, early labor can last a long time — your provider may suggest staying home until contractions are closer together and more intense. If you live far from the hospital or have a history of fast labor, your provider may recommend going earlier. When in doubt, call.
Product picks for week 39
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Contraction timing app (free)
When labor starts, a contraction timer on your phone tracks frequency, duration, and pattern — essential for knowing when to go to the hospital.
Lip balm and face mist for labor
Hospitals are dry, and labor is dehydrating — lip balm and a cooling face mist are small comforts that make a real difference.
Coming home outfit for baby
Choose something soft, easy to put on, and weather-appropriate — your baby's first real-world outfit is a keepsake moment.
A quick note: This content is for informational purposes only and is not a substitute for professional medical advice. Always talk to your healthcare provider about any questions or concerns. Learn how we create our content.
Content based on guidance from the American College of Obstetricians and Gynecologists (ACOG), the American Academy of Pediatrics (AAP), Mayo Clinic, and peer-reviewed medical literature. Learn more about how we create our content.