Week 39 of Pregnancy

🤱

Your baby is the size of: Watermelon

Approximate length50 cm
Approximate weight3.3 kilograms
TrimesterThird
Pregnancy monthNinth

Baby Size Comparison in Week 39

In week 39 of pregnancy your baby measures about 50 cm long and weighs about 3.3 kilograms: roughly the size of Watermelon. Remember these are approximate averages from standard growth charts; every baby grows at their own pace, and your doctor follows your baby's personal growth curve across visits, not a single number. If an ultrasound measures a little bigger or smaller than average, that is usually normal as long as growth continues at a steady rate.

Baby Development in Week 39

The outer skin layer constantly renews, so the skin becomes smooth and pink, and the brain keeps growing quickly and forming the nerve connections that will support learning after birth. The lungs are strong and the muscles firm; kicks and pushes are strong and sometimes painful.

Fat storage continues, so the weight increases about 200 grams this week. The nails may need trimming right after birth. The baby is engaged in the pelvis in the ideal birth position, usually. The weight is about 3.3 kilograms and the length 50 cm; the size of a medium watermelon. All its organs are ready; it is now just waiting for the start signal from your body.

The outer skin layer constantly renews, so the skin becomes smooth and pink, and the brain keeps growing quickly and forming the nerve connections that support learning after birth. The lungs are strong and the muscles firm; kicks and pushes are strong and sometimes painful. Fat storage continues, so the weight increases, and the nails may need trimming right after birth. The baby is engaged in the pelvis in the ideal birth position, usually. All its organs are ready; it is now just waiting for the start signal from your body.

Your Body Changes in Week 39

Anticipation is at its peak: every twinge raises the question (has it started?). Strong false contractions, back pain, severe pelvic heaviness.

Sleep is nearly impossible in a comfortable position; try sleeping semi-upright on the sofa. Constant urination, discharge, and total exhaustion. Weight gain is about 14 to 19 kilograms. Emotionally: a mix of excitement, fear, and exhaustion; talk to those who have been through it, and remember that millions of women do this daily with success. Prepare yourself mentally to meet the most important person in your life.

Every twinge raises the question; watch the regularity of contractions. Semi-upright sleep may ease you more. Spend quiet time with your partner. And prepare yourself mentally to meet the most important person in your life.

Practical Tips for Week 39

Frequently Asked Questions About Week 39

How do I know birth is near?

Signs that birth is near: the baby's head dropping into the pelvis (better breathing and more urination), the mucus plug coming out (slightly bloody, jelly-like discharge), mild diarrhea, more Braxton Hicks contractions, and the nesting instinct. Actual birth announces itself with regular, close contractions that do not ease, or the water breaking; then head to the hospital immediately.

Is my baby's size in week 39 the same in every pregnancy?

No. The lengths and weights shown are approximate averages from standard growth curves, and every baby grows at their own pace. What matters is your baby's personal growth curve across checkups: steady growth at a consistent rate is the reassuring sign, not any single number.

What month am I in during week 39?

Week 39 falls in the ninth month of pregnancy (the ninth month = weeks 36-40), within the third trimester.

⚕️ Medical note: Medical note: results are for guidance and do not replace your doctor. If your cycles are irregular or yours is a high-risk pregnancy, always consult your doctor.
← Week 38 Week 40 → All Weeks

Calculate your current week with the pregnancy weeks & months calculator →

Last reviewed: 2026-10-07

Related articles & tools