Preterm delivery linked to lower IQ in adulthood, finds study

Preterm birth is a worldwide epidemic with a global incidence of 15 million per year. In the latest online issue of JAMA pediatrics, a study shows that adults who were born very preterm (VPT)/very low birth weight (VLBW) had lower IQ scores than adults who were term born.

Earlier there were few individual studies showing preterm and low birth weight individuals associated with, lower IQ than their term counterparts. Robert et al performed the first systematic review and meta-analysis of adult IQ among VPT/VLBW individuals.

Researchers at University of Warwick, United Kingdom performed aggregate meta-analysis of 13 studies comprising 1068 VPT/VLBW participants and 1067 term-born participants. The primary objective was to compare the difference in adult IQ among VPT/VLBW participants' vs. a control group of term-born participants, and the second was to examine cohort and individual-level factors associated with adult IQ among VPT/VLBW participants.

Key findings of the analyses were:

1. Mean IQ z scores among VLBW/VPT participants were 0.78SD (95% CI, -0.90 to -0.66 SD) lower than those of term born participants.

2. Upon analysis, it was observed that VLBW/VPT individuals scored 0.78SD lower in IQ score than term-born participants which is equivalent to between-group difference of 12 IQ points.

3. Gestational age at birth and birth weight had significant association with IQ z score, for example among VPT/VLBW individuals, each extra week of gestation was associated with an increase in IQ z score of 0.11(equivalent to 1.65 IQ points).

4. Presence of neonatal BPD and any grade of IVH were associated with low IQ in the VLBW/VPT group.

5. In contrast to neonatal factors, maternal education level was studied, neonates who had mothers with medium and high IQ had higher IQ levels compared to low educated mothers.

To summarize, individuals with lower gestational age, lower weight for gestation, certain neonatal morbidities and low maternal education levels were all important risk factors associated lower IQ among VLBW/VPT born young adults.

Authors conclude that-"provision of antenatal and neonatal care that is associated with reduction in BPD , IVH and parenting educational interventions may improve cognitive outcome among preterm born adults."

Sourcee: Eves R, Mendonça M, Baumann N, et al. Association of Very Preterm Birth or Very Low Birth Weight With Intelligence in Adulthood: An Individual Participant Data Meta-analysis. JAMA Pediatr. Published online May 28, 2021. doi:10.1001/jamapediatrics.2021.1058