Compared to early postpartum (10-15 weeks) observations, paracetamol clearance was significantly higher (21.1 vs 11.7 l.h-1, + 80 %) at delivery. This higher clearance was due to a disproportional increase in glucuronidation (11.6 vs 4.76 l.h-1, + 144 %), a proportional increase in oxidation clearance (4.95 vs 2.77 l.h-1, 78 %) and primary renal clearance (1.15 vs 0.75 l.h-1, 53 %) [KUlo et al, Int J Obstet Anesth]. This increase in glucuronidation clearance may in part be driven by oestradiol, and may explain within and between individual differences in paracetamol metabolism (e.g. oral contraceptives, follicular vs luteal phase, postpartum, pregnancy, or duration of pregnancy) in young women.

Based on a pooled analysis, investigators aimed to further explore the impact of these covariates on paracetamol metabolism based on plasma and urine collections in women at delivery, in postpartum (early, or late) and healthy volunteers, either or not on oral contraceptives (OC) following intravenous (iv) paracetamol administration.

This study aims to perform a pooled analysis of:

1. Paracetamol PK data recently published in 47 pregnant women. In these cases, iv paracetamol was administered q6h after delivery (caesarean) for 24 h. 8 were recruited a second time for an additional single dose pK study in postpartum (Kulo et al, Br J Clin Pharmacol 2013).
2. The PK data as initially published by Gregoire et al, but limited to female volunteers, all on oral contraceptives (n=14) (Gregoire et al, Clin Pharm Ther 2007)
3. A dataset in 8 young women not on oral contraceptives, iv paracetamol, single dose.

Inclusion Criteria:

1. informed consent
2. for patients (pregnant women at delivery), there has to be a clinical indication (post caesarean analgesia, NPO) to administer iv paracetamol.

Exclusion Criteria:

1. intolerance to paracetamol
2. withdrawal of informed consent.

Pooled analysis of different cohorts of young women who all underwent PK study on paracetamol disposition after iv paracetamol administration.