Who Does Developmental Delay Affect?

In the United States, 17% of children under the age of 18 years – or one in six – have a developmental or behavioral disability such as autism, intellectual disability, or attention-deficit/hyperactivity disorder (ADHD). These conditions may initially present as developmental delays. Less than 50% of these children are identified as having a problem before starting school, by which time significant problems may have already occurred and opportunities for treatment have been missed.

There is definitely a gender bias when it comes to developmental delays, with more males affected than females. The higher proportion of males with developmental delay and disabilities is well documented. This is in part due to X-linked conditions (such as fragile X syndrome, the most common cause of inherited intellectual disability). X-linked conditions are genetic diseases carried on the X chromosome. Girls have two X chromosomes and boys have 1 X chromosome (and one Y chromosome).  Since boys only have one X chromosome, any abnormality on that chromosome will be expressed clinically (conversely because girls have two X chromosomes, an abnormality can be carried on one X chromosome but not be clinically evident because of the other normal X chromosome that the girl has). However, the increased prevalence of developmental challenges in boys is not all explained by X-linked conditions. For example 4 times as many  boys have autism compared to girls. There is also a racial predisposition, with black males affected more than white males, black females, or white females. The underlying reason for this has been attributed to socioeconomic disparities.

The major risk factors for developmental delay or adverse neurodevelopmental outcome include maternal and child factors. The following are some of the most common:

Maternal Factors

Any of the following characteristics of a mother raise the possibility that she may have a child with developmental delay.  These factors are associated with an increased risk but not necessarily causative.  No all mothers with these characteristics will have a child with developmental delay and some mothers who have children with developmental delay have none of these characteristics:

  • mother having 12 or fewer years of education
  • unwed marital status
  • prenatal care beginning after the third month of pregnancy
  • tobacco use during pregnancy
  • alcohol use during pregnancy
  • medical history factors (anemia, poor nutrition, infections, diabetes, hypertension)
  • complications of labor and/or delivery
  • age of the mother under 18 at delivery

Child Factors

Some child characteristics raise the risk the child will have developmental delay but not all children with these characteristics will a have delays and not all children with developmental delay will have one of these factors:

  • gestational age less than 37 weeks 
  • birth weight under 2,500 grams (5 ½ pounds)
  • Apgar score (at 5 minutes) of less than 7; this is an assessment of the physical condition of a newborn infant, with scores ranging from 0 to 10
  • multiple births (e.g., twins, triplets, quadruplets)
  • presence of newborn medical condition (such as anemia)
  • congenital abnormality

Find Support

Connect with other parents of children with Developmental Delay

Visit the My Child Without Limits support community and talk to parents, caregivers, and professionals about their experiences with Developmental Delay.


American Academy of Pediatrics

Developmental Delay Resources (DDR)

First Signs 

National Center on Birth Defects and Developmental Disabilities
Learn the Signs. Act Early (with checklists for Developmental Milestones)


National Center of Medical Home Initiatives for Children with Special Needs

Zero to Three