Objective To investigate the effect of gestational age, particularly late preterm birth (34–36 weeks gestation) and early term birth (37–38 weeks gestation) on school performance at age 7 years.

Design Population-based prospective UK Millennium Cohort Study, consisting of linked educational data on 6031 children.

Methods School performance was investigated using the statutory Key Stage 1 (KS1) teacher assessments performed in the third school year in England. The primary outcome was not achieving the expected level (≥level 2) of general performance in all three key subjects (reading, writing and mathematics). Other outcomes investigated subject-specific performance and high academic performance (level 3).

Results 18% of full-term children performed below the expected KS1 general level, and risk of poor performance increased with prematurity: compared to children born at full-term, there was a statistically significant increased risk of poor performance in those born very preterm (<32 weeks gestation, adjusted RR 1.78, 95% CI 1.24 to 2.54), moderately preterm (32–33 weeks gestation, adjusted RR 1.71, 95% CI 1.15 to 2.54) and late preterm (34–36 weeks gestation, adjusted RR 1.36, 95% CI 1.09 to 1.68). Early term children performed statistically significantly worse in 4 out of 5 individual subject domains than full-term children, but not in the primary outcome (adjusted RR 1.07, 95% CI 0.94 to 1.23).

Conclusions Late preterm, and to a lesser extent, early term birth negatively impact on academic outcomes at 7 years as measured by KS1 assessments.