Association between skin-to-skin contact and cognition and behaviour at 5 years in children born at 24-31 weeks' gestation: a secondary analysis of a national population-based prospective cohort study.

Background: Long-term effects of Skin-to-Skin Contact (SSC) on neurodevelopmental outcome for preterm children are still debated. We aimed to evaluate associations between SSC, cognition and behavior at 5 years among children born at 24-31 weeks of gestation. Methods: In this secondary analysis of the French Etude Epidémiologique sur les Petits Ages Gestationnels (EPIPAGE-2), a nationwide prospective population-based cohort study conducted in all neonatal units across 25 French regions from Mar 28, 2011, to Dec 31, 2011, we examined preterm-born children divided into two groups based on exposure to skin-to-skin contact (SSC) during the first week of life. Outcomes at 5 years included full-scale intelligence quotient (FSIQ; Wechsler Preschool and Primary Scale of Intelligence, 4th edition) and behavioural difficulties (Strengths and Difficulties Questionnaire, SDQ), using a contemporaneous group of term-born children from the ELFE cohort as a reference. The ELFE cohort enrolled participants during four inclusion periods in 2011: Apr 01-04, 2011; Jun 27-Jul 04, 2011; Sep 27-Oct 04, 2011; and Nov 28-Dec 05, 2011. Included children were born at 24-31 weeks of gestation, remained in the same neonatal unit during the first week of life, were alive at 7 days, had no severe cerebral malformations or decisions to limit/withhold care, and had data on SSC exposure. Results are given after multiple imputation using propensity score methods with inverse probability of treatment weighting approach. Findings: Of 3669 live-born preterm children, 2726 children were eligible and 2666 included with SSC information during the first week of life available; 2561 survived to 5 years (1328 boys (51.8%). Among survivors, 1581 received SSC during the first week of whom 987 had full follow-up assessment; 980 were not exposed of whom 558 had full follow-up assessment. SSC exposure increased with gestational age (21.7% at 24 weeks to 78.0% at 31 weeks), with variability across neonatal units (range 5%-100%). Compared with non-exposed children, exposed children had higher FSIQ scores (mean difference +2.3, 95% CI [+0.3 to 4.3], p = 0.024) and were more likely to score ≥-1 standard deviation (odds ratio 1.33, 95% CI [1.04-1.70], p = 0.023). There was no significant difference in SDQ scores between groups (mean difference -0.3, 95% CI [-1.1 to 0.5], p = 0.42 and score ≥90th percentile odds ratio 0.92 [0.64; 1.33], p = 0.66). Interpretation: While the duration of SSC the first week of life and SSC beyond the first week were not accounted for, our findings suggest that SSC during the first week of life may be associated with an increased likelihood of higher FSIQ at 5 years. These results point to a potential neuroprotective role of SSC during this early sensitive postnatal period and highlight important areas for improvement. Variability in SCC implementation across units deserves attention and further research is needed to explore dose-response relationships and timing effects. Funding: The National Research Agency (via the French Equipex Program of Investments in the Future); the French Institute of Public Health Research/Institute for Public Health and its partners at the French Health Ministry; the National Institute of Cancer; the National Institute of Health and Medical Research; the National Solidarity Fund for Autonomy; and the PremUP Foundation.