The Prematurity Paradox
Premature children face a series of unique challenges in their lives. For instance, although an infant’s chronological age on the day they are born is 0 years and 0 months, an infant born 4 months prematurely can be developmentally viewed as 0 years and -4 months old. This deficit is accounted for by early developmental assessments with metrics like “corrected age,” which adjusts an infant’s age by subtracting the period of the missed gestational period due to early birth. The corrected age is used for up to 2 years post-birth, by which time most preterm children are expected to have “caught up” to their full-term counterparts or otherwise be labeled as delayed. From then on, the progression to subsequent developmental milestones, like kindergarten entry, is determined by using chronological age (ie, turning 5 years old by a certain “cutoff” date).
Yet, there is evidence that this discarding of gestation period consideration occurs too soon. Preterm children often have reduced kindergarten readiness compared with their peers, which may arise because they are still relatively young. Cutoff dates can also exacerbate the disadvantages of preterm children. For example, in New York City, which has a kindergarten age cutoff date of December 31, a December-born, extremely preterm child enters kindergarten at the chronological age of 4 years 10 months but can be understood to be only 4 years 6 months old from a developmental perspective. This distinct disadvantage will continue throughout the child’s school years, placing them at an increased risk of academic interventions and grade retention. A potential preventative measure is to selectively delay kindergarten entry for certain preterm children who demonstrate need. These children could then begin elementary school at a more appropriate age, as well as be on a similar developmental footing to their full-term peers.
Call to Action
We call on nationwide school districts to consider gestational age (GA) and timing of birth when determining kindergarten readiness in cases of substantial prematurity. Pediatricians are uniquely poised to advocate for parents and preterm children and can do so by asserting that certain former preterm infants, such as those born months preterm, are disadvantaged by the current chronological age standards. On a case-by-case basis, and after close consultation with pediatricians, school districts should offer the option of delaying kindergarten in lieu of a no-cost alternative, like an additional year of public preschool with all associated support services.
Kindergarten Readiness
Because 10% of children in the United States are born preterm, ∼16% of whom are early preterm (<32 weeks), hundreds of thousands of preterm children are set to encounter the crucial developmental milestone of kindergarten each year. At this time, children are often assessed for “kindergarten readiness,” which broadly refers to their ability to adapt to a kindergarten classroom. Children must be prepared to develop academic competencies, as well as learn how to healthily engage with their peers, manage emotions, and resolve conflicts. Kindergarten also demands that children possess a certain level of motor skills for writing, drawing, recess activities, and self-care behaviors, like dressing or tying shoelaces. If a child is lacking in any of these developmental domains, they may be unable to succeed alongside their peers, leading to outcomes like social exclusion or bullying. Such poor outcomes during kindergarten can result in a child developing a negative relationship with compulsory education, as well as experiencing more pronounced deficits as they progress through the cumulative nature of elementary school. This may then result in mitigation steps, namely grade retention, that can be ineffective or damaging to a child’s self-esteem.
Kindergarten Readiness and Preterm Children
Research reveals a general trend toward reduced kindergarten readiness for children who are born preterm.1 Preterm children (<37 weeks) are more likely to be classified as vulnerable (<10th percentile on a standardized teacher questionnaire) in many facets of kindergarten readiness, including physical health and wellbeing, social competence, emotional maturity, language and cognitive development, and communication skills.2 Many of these deficits can be attributable to the relatively low GA of preterm children because GA has been shown to correlate with positive school outcomes, like gifted status, wellbeing, and emotional maturity.1,3 However, as is the case for many public health and educational disparities, the educational outcomes of former preterm children may also be intertwined with socioeconomic status (SES). When factors related to SES, namely preschool attendance, are controlled for, some of the developmental risks associated with low GA can be reduced.3 Although this introduces SES as a possible confounder for the relationships observed between poor educational outcomes and low GA (low SES corresponds with a higher prevalence of premature births), it also indicates that policies supporting additional pre-K schooling could be a useful intervention for disadvantaged preterm children.
Kindergarten Delay
There is a potential mechanism for the observed developmental deficits of preterm children outside of the physiologic consequences of a low gestation period. Unsurprisingly, the age at which a child enters kindergarten has implications for their development. Age 5 cutoff dates can result in some kindergarteners (ie, those who were born just before the cutoff date) being up to 1 year younger than their oldest classmates. This difference matters. According to the New York City Independent Budget Office, New York City children born just after the December 31 cutoff date (in January or February) have a lower average rate of disability classification than children born just before the cutoff date (ie, in November or December). Similar differences in attention-deficit/hyperactivity disorder diagnosis rates have been found in other states that use a September 1 cutoff date.4
Kindergarten delay offers a potential solution to this age-of-entry issue, which has pushed some parents to “redshirt” their child for a year, even if they were born full-term. Although kindergarten delay and, by extension, preschool retention, have not consistently been shown to provide an advantage for typically progressing children over their peers, some research indicates that it is, at the least, preferable to kindergarten retention. Some researchers have found that children who were retained in kindergarten are at a greater risk of poor school adjustment compared with those peers who delayed entry and had lower high school scores in language and mathematics; the researchers speculated that this was due to the esteem issues that often accompany retention.5
For preterm children specifically, there is evidence that delayed entry may be beneficial, especially in cases in which a premature birth results in a child beginning school 1 year earlier than expected. “Early entry” occurs when, for example, a premature child with an expected due date of April 1 is, instead, born on December 1, just before a December 31 cutoff date. The authors of a United Kingdom study who specifically investigated this phenomenon found that GA corrections could account for the adverse educational outcomes of preterm children aged 5 to 7 but only for those preterm children who did not begin primary school 1 year early as a result of their prematurity.6 Conversely, educational deficits of the cohort of preterm children who did begin schooling 1 year early were not erased after GA adjustment, suggesting that early entry is a risk factor for developmental challenges.6 The authors concluded that for this population of preterm children (those positioned to face early entry), kindergarten delay may be an appropriate intervention.6
The Corrected Age Solution
Determining preterm child eligibility for the supportive measure of kindergarten delay can be accomplished with corrected age. Despite the metric’s widespread lack of utilization past the age of 2, there is evidence to suggest that corrected age can be valid for kindergarten-aged children. For example, research has revealed that common developmental assessments standardized by chronological age often underestimate the abilities of preterm children.7 Importantly, this underestimation occurs past the age of 3 years. In one study, as many as 22% of 7-year-olds were no longer characterized as “at risk” of learning difficulties when their corrected age was considered.7 This percentage is likely even higher for those who are born early preterm.7
Using corrected age to determine kindergarten entry should not only lower the rate of incorrect disability classifications for former preterm children but also increase their ability to access special education services. In New York, for example, former preterm children are supported by early intervention programs from 0 to 3 years old, before transitioning to Committee on Preschool Special Education (CPSE) services from the ages of 3 to 5. Past 5 years old, however, public pre-K and CPSE services cease because children are expected to then move into the support networks of elementary schools. Yet, this poses a significant issue for parents of former preterm children. Should they choose to send their relatively young child into kindergarten and, therefore, access the next level of services, they face the risk of their child facing inordinate academic and social challenges. Should parents choose to delay kindergarten, they are saddled with a year of childcare costs.
An extension of public pre-K and CPSE services will necessitate funding, but it is likely that the children who use such services would eventually require additional support anyway. Increased service availability before kindergarten has the potential to be an investment that decreases the need to fund later services, such as special education, grade retention, or occupational therapy. Specifically, using measures like kindergarten delay can ensure that some former preterm children start elementary school at a more appropriate corrected age, as well as a more level developmental footing to their full-term peers. This, in turn, can lower their risk of falling behind and requiring interventions at an older age.
Conclusions
The consequences of prematurity vary greatly and, as such, so do the supportive needs of former preterm children. Considerations of corrected age on kindergarten entry will not always be relevant; some preterm children will be more than prepared for kindergarten, whereas others will already have obvious developmental issues that kindergarten delay will not rectify. However, for certain cohorts of former preterm children, like those born early preterm and on the wrong side of an age 5 cutoff date, the use of corrected age can elucidate why entering kindergarten may be inadvisable. In these instances, pediatricians can attest that an additional year of development will be beneficial and subsequently, recommend to school districts that the child’s kindergarten year is delayed while pre-K services are extended.
Mr Barile conceptualized the piece, conducted parts of the literature review, drafted and edited the manuscript, and responded to revision requests; Mr Han conceptualized this piece, conducted parts of the literature review, assisted with drafting the manuscript, and assisted with manuscript edits; Dr Milanaik identified this original issue, conceptualized the piece, and critically reviewed the manuscript; and all authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
COMPANION PAPER: A companion to this article can be found online at www.pediatrics.org/cgi/doi/10.1542/peds.2023-063654.
FUNDING: No external funding.
CONFLICT OF INTEREST DISCLOSURES: The authors have indicated they have no potential conflicts of interest relevant to this article to disclose.
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