Immediate skin-to-skin contact at very preterm birth and effect on infant socio-emotional stress response and mother–infant cortisol co-regulation: secondary outcomes from the randomised clinical Immediate Parent-Infant Skin-To-Skin Study (IPISTOSS)

OBJECTIVE: To explore the effects of immediate parent-infant skin-to-skin contact (iSSC) at very preterm birth on maternal-infant behavioural responses and hypothalamic-pituitary-adrenal (HPA) axis reactivity to age-appropriate socio-emotional stress at 4 months corrected age. DESIGN: Two secondary outcomes from a multicentre randomised controlled trial with two non-blinded parallel groups. SETTING: Three Scandinavian neonatal intensive care units, level 2 and level 3. PARTICIPANTS: 91 infants born at gestational age 28+0 to 32+6 from April 2018 to June 2021. Singletons and twins with a second caregiver present were included, regardless of mode of birth. Higher-order births, infants with congenital infections and major malformations were excluded. INTERVENTION: Infants were randomised before birth to iSSC (n=46) or conventional care (n=45) during the first 6 hours of life. At 4 months corrected age, the infants were exposed to socio-emotional stress using the Face-to-Face Still-Face procedure (FFSF). Salivary cortisol was collected before and after FFSF. MAIN OUTCOME MEASURES: Behavioural and hormonal stress responses at 4 months of age. RESULTS: 65 of 91 infants were assessed by FFSF, of which 37 infants had cortisol sampling. The iSSC group demonstrated heightened positive emotionality during FFSF compared with controls (beta 0.74, 95% CI 0.40 to 1.07; p