“Each week of gestation up to 39 weeks is important for a fetus to fully develop before delivery and have a healthy start.”8
Jeffrey L. Ecker, MD, chair of the American College of Obstetrics & Gynecology’s Committee on Obstetric Practice
The last few weeks of pregnancy—37-40 weeks—allow a baby’s brain and lungs to fully mature. Babies born after 39 weeks of pregnancy have the best health outcomes, compared with babies born before or after this period.12 You can learn more about your baby’s fetal development during key weeks of your pregnancy below.
According to the March of Dimes, the preterm birth rate in the U.S. was 9.6% in 2014, or approximately 1 in 10 pregnancies — one of the highest rates in the developed world.13
Why It's Important for Babies to Develop Fully
Babies that survive being born prematurely may face immediate and long-term health challenges, including cerebral palsy, vision and hearing loss, other chronic conditions, and problems in school. They are also more likely to die from sudden infant death syndrome (SIDS).14
Your baby's ears are getting better at hearing. So go ahead, talk to your baby!
Your baby is about the size of a small cantaloupe and weighs 1.3 lbs.
24 weeks is typically the earliest that most babies can survive outside of the womb. These babies will require round-the-clock care in the Neonatal Intensive Care Unit (the ‘NICU’) to help them survive. When these babies survive, they are at life-long risk for developmental/intellectual risks and chronic medical disorders. 15
Baby's eyesight is still developing, but now he or she can blink.
Your baby is now approximately the size of an eggplant and weighs about 2.25 lbs.
Your baby’s eyes, brain, nervous system and lungs are still developing. These babies are at very high risk for Respiratory Distress Syndrome (RDS)—a breathing disorder that affects premature babies. It rarely occurs in full-term babies. 15
Your baby has grown fingernails, toenails and hair. For the next 6-7 weeks, your baby will gain 1/2 lb/week, which helps your baby retain heat when born.
Now about the size of a pineapple, your baby weighs around 3.75 lbs.
Babies born this early may face serious health issues. These preemie babies still have a high risk of RDS. Babies with RDS will need extra oxygen and help breathing until their lungs develop enough for the baby to breath on their own. 15
Your baby may have already turned head down in your uterus, getting ready for birth.
About the size of a butternut squash, your baby has grown to about 4.7 lbs.
34-week babies are still immature. In addition to breathing problems, they can struggle with problems related to blood sugar, blood pressure and infection. Some have problems breast or bottle feeding. 15
Your baby's brain is still developing.
Now the size of a romaine lettuce, your baby typically weighs a little over 5.75 lbs.
Many 36-week babies go to NICU for observation and special care. They are still at risk for developmental and academic delays compared to a full-term baby. 15
Most organs are developed...but the lungs continue to develop to birth.
A pumpkin! Typical weight about 7 lbs.
It is now a waiting game for you as your baby continues to develop. These babies may look as healthy as a full-term baby (39-41 weeks) but may still have breathing problems, suffer from infections, and require admission to NICU. Don't get too anxious your bundle of joy will be here soon enough. 15
Knowledge is power
It's important to know your risk of delivering early for this pregnancy. There are established interventions designed to help prolong your pregnancy with the goal of helping your baby develop more fully. Talk to your Doctor