Influence of medication, pain and progress in labour on plasma β-endorphin-like immunoreactivity

Abstract

Plasma β-endorphin-like immunoreactivity (β-ELI) was measured at intervals during labour in 42 patients. An increase in β-ELI occurred during labour and increased to a maximuM.During the second stage. The increase in β-ELI paralleled dilatation of the cervix. A correlation existed between the duration of labour and second stage β-ELI in patients with labours of more than 4 h duration. Analgesic drugs were associated with changes in P-ELI. The patients who received Entonoz had greater plasma β-ELI concentrations than those who received pethidine. A significant difference in the second stage β-ELI existed between those who received only Entonox and those who received only pethidine. Induction and augmentation of labour were also associated with differences β-ELI. Patients in spontaneous labour had significantly lower β-ELI than patients who had either artificial rupture of membranes or Syntocinon augmentation of labour. © 1982 The Macmillan Press Ltd.