Although individual children grow at different rates, full-term babies delivered after 37 weeks have had more time to develop before birth. As a result, they're more likely to hit their developmental milestones on time, whereas infants born prematurely may lag behind. Noted pediatrician Dr. William Sears explains that the timing of certain milestones varies for any infant, particularly when it comes to a baby's gross motor development.
Babies born prematurely normally reach some of their developmental milestones later than babies who are born full term. The body systems of an infant born prematurely don't function the same as an infant born at 40 weeks because they haven't had as much time to develop. That's why preemies often hit milestones later than full-term babies. While most premature infants do well after birth, some of the smallest preemies still experience serious developmental delays or physical disabilities that require more intervention. Not only preemies can have problems, however. Babies born after 42 weeks can suffer developmental delays as well.
A post-term pregnancy is one that goes longer than 42 weeks, with the risk of complications increasing if you deliver after 40 weeks. An infant born post-term can weigh more and experience breathing problems at birth. Your baby may also be smaller. After you pass your due date, the placenta begins to weaken. Because he's not getting enough oxygen and nutrients, your baby's growth slows and he may not continue to develop normally in the womb. After 40 weeks, the amount of amniotic fluid surrounding the baby can decrease, pinching the umbilical cord and reducing the amount of oxygen and nutrients your baby gets. A lack of oxygen for an extended period can cause brain damage and lead to the baby suffering long-term disability and developmental delays after birth.
Delays in development milestones include learning disabilities identified in school-age children. While motor development is an early milestone in infants, delays in language and cognition can lead to poor reading skills and problems learning as a child grows. An article published by "The Guardian" in 2012 reports that babies born post term are at higher risk of developing behavioral and learning problems. Results of the Dutch study, which was published in the "International Journal of Epidemiology," shows that late-term babies were twice as likely as infants born at full term to show signs of attention deficit hyperactivity disorder, known as ADHD.
Normal Developmental Progression
Timing isn't nearly as important as progression when it comes to a baby's developmental milestones, points out Dr. Sears. Even if your baby seems a little behind other babies his age, as long as he continues to gradually develop his motor skills, he's still on track. The time to worry is if he shows no new development after two or three months. If that happens, it's time to talk to his pediatrician, as a problem with development in one area could mean delays in other developmental milestones.
- Parenting: Ask Dr. Sears – Late Crawler
- ParentsCanada: Will Preemies Hit Milestones at the Same Time as Full-Term Babies?
- California Childcare Health Program: What to Expect from a Preemie in the First Year
- The Guardian: Babies Born Late More Likely to Have Behavioral Problems
- Medline Plus: When you Pass Your Due Date
- Emory University School of Medicine, Department of Pediatrics: Developmental Milestones