Rectal paracetamol in newborn infants after assisted vaginal delivery may increase pain response

To assess the efficacy of paracetamol (acetaminophen) for neonatal pain relief.

Randomized, double-blind placebo-controlled trial in 3 Swiss university hospitals. Term and near-term infants (n = 123) delivered by forceps or vacuum were randomized to receive 2 suppositories with paracetamol (60/80/100 mg in infants <3000 g/3000-4000 g/>4000 g birth weight) or placebo at 2 and 8 hours of life. Pain and discomfort during the first 24 hours was assessed by the échelle de douleur et d'inconfort du nouveau né [neonatal pain and discomfort scale] score. The response to the subsequent heel prick for metabolic screening at days 2-3 of life was investigated by the Bernese Pain Scale for Neonates (BPSN).

The échelle de douleur et d'inconfort du nouveau né [neonatal pain and discomfort scale] pain scale ratings after assisted vaginal delivery were low and declined within 4 hours of life (P < .01) irrespective of paracetamol administration. At 2-3 days of life, BPSN scores after heel prick were significantly higher in infants who had received paracetamol, compared with controls, both when BPSN were scored by nurses at the bedside (median [IQR] 4 [2-7] vs 2 [0-5], P = .017) or off-site from videos (4 [2-8] vs 2 [1-7], P = .04). Thirty-five of 62 (57%) infants treated with paracetamol cried after heel prick, compared with 25 of 61 (41%) controls (P = .086).

Infants born by assisted vaginal delivery have low pain scores in the immediate period after birth. Paracetamol given to newborns soon after birth may aggravate a subsequent stress response.