Preterm Children Show Poorer Cognitive Scores, Academic Performance at 9 Years

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Authors of a study published in JAMA Network Open aimed to address knowledge gaps by estimating whether being born moderate to late preterm (MLP) compared with being born early term or later is associated with cognitive ability, academic performance, motor function, behavior, and social communication skills at 9 years of age. Additionally, the authors aimed to assess factors in the newborn period and infancy that were associated with poorer neurodevelopment at 9 years of age.

This prospective, longitudinal cohort study recruited children born MLP as well as children born early term or later (≥37 weeks’ gestation) with a healthy birth weight (≥2500 g) at a single tertiary hospital in Melbourne, Victoria, Australia. Births occurred between December 7, 2009, and March 26, 2014, and 9-year follow-ups occurred between June 20, 2019, and February 27, 2024. The follow-up assessments were 2 days in duration.

Perinatal, neonatal, and maternal data were collected prospectively. Additionally, socioeconomic risk was assessed at the 9-year follow-up using the following 6 variables: family structure; educational level of the primary caregiver; employment status and occupation of the primary income earner; language spoken at home; and maternal age at the time of the child’s birth. Variables were scored on a 3-point scale, with 0 indicating lowest risk and 2 indicating higher risk.

Children were assessed by trained assessors who were unaware of birth status or clinical history. Cognitive ability was measured using the fifth edition of the Wechsler Intelligence Scale for Children (WISC). Full-scale IQ (FSIQ) was also used as a measure of general intelligence, with age-standardized index scores from the 5 domains of cognitive functioning: verbal comprehension, visuospatial, fluid reasoning, working memory, and processing speed.

Data were available for 159 children born MLP and 137 born early term or later. Compared with those who were born early term or later, children born MLP were more likely to be born following assisted conception, in a multiple birth, via a cesarean delivery, and receive respiratory support following birth. Additionally, these children were born with lower birth weight scores and higher socioeconomic risk.

Further, children born MLP had lower mean FSIQ scores (105.2) compared with those born early term or later (110.1; −4.4 [95% CI, −7.7 to −1.0]). Additionally, results were found to similar for most other cognitive domains, but the greatest differences in verbal comprehension, visuospatial, and working memory indices. Children born MLP had poorer performances reading (103.0) and doing math () compared with their counterparts born early term or later (reading: 107.3, −4.0 [95% CI, −7.0 to −1.1]; math: 101.5, −5.0 [95% CI, −8.8 to −1.2]). Overall standard scores for motor function and dexterity were also similar between groups (8.4 vs 9.1; −0.9 [95% CI, −1.8 to 0.04]).

In addition, the number of children with no dichotomous outcome impairment was similar between groups. The rate of any academic impairment in the group born MLP was similar to that among children born early term or later (adjusted RD, 6.4%; 95% CI, −6.8% to 19.7%). Rates of impairment in cognition, motor, or communication problems were also similar between the 2 groups; however, the children born MLP (n = 50, 31.7%;) often presented more behavioral difficulties than children born early term or later (n = 29, 21.5%; adjusted RR: 1.57 [95% CI, 1.06-2.33]; adjusted RD: 12.8% [95% CI, 2.1%-23.5%]).

Any present developmental delay at 2 years of age was associated with impairments in all developmental domains at 9 years. Receiving antenatal corticosteroids was associated with motor impairment and behavioral difficulties, and higher socioeconomic risk was associated with cognitive impairment and poorer social communication. In addition, higher gestational age and multiple birth were associated with better social communication.

The main limitation of the study was that retention rates at 9 years being lower than those at the 2-year follow-up. The authors note that this may be a result of the COVID-19 lockdowns that occurred in Victoria, Australia. Additionally, the authors noted that using only 1 tertiary center cohort may be a better representation of children who were sicker at birth, and therefore, are more likely to experience developmental delays compared with the whole population of children born MLP.

REFEERENCE

Cheong JLY, Mainzer RM, Doyle LW, et al. Neurodevelopment at Age 9 Years Among Children Born at 32 to 36 Weeks’ Gestation. JAMA Netw Open. 2024;7(11):e2445629. doi:10.1001/jamanetworkopen.2024.45629