Factors influencing postnatal liver function tests

Objective To investigate liver function tests (LFTs) changes in the puerperium and the influence of specific obstetric events on these changes. Design A longitudinal observational study. Setting West Middlesex University Hospital, Twickenham. Population Ninety‐four women with uncomplicated pregnancy who delivered at term. Methods Aspartate transaminase (AST), alanine transaminase (ALT), gamma glutamyl transferase (GGT), total bilirubin (Bilirubin) and alkaline phosphatase (ALP) were measured in early labour and on day 1, day 2, day 5 and day 10 postnatal. Main outcome measures Peak enzyme concentration, time of peak enzyme concentration, the area under the curve for each enzyme and the rate of change of enzyme level from predelivery to peak concentration. Results All LFTs were affected by delivery (P < 0.001), increasing by 88% (0.500%) on day 2 or day 5 for AST, 147% (0–1140%) on day 5 for ALT and 63% (0–450%) on day 5 or day 10 for GOT. Multiple linear regression showed that caesarean section and opioid administration was associated with a faster rise in AST (P= 0.001, P= 0.033 respectively). The mean peak GOT concentration was 39% higher in women having caesarean section compared with vaginal delivery (P= 0.015). Univariate analysis showed that perineal trauma, use of Entonox, maternal age at delivery and breastfeeding also influenced LFT concentration significantly. Conclusion Liver enzyme levels change significantly in the puerperium and are affected by common obstetric events, particularly caesarean section. This study aids clinical interpretation of postnatal LFTs in women recovering from liver‐related illnesses, by facilitating the differentiation of physiological and pathological processes.