Skovlund 1991a.

Study characteristics
Methods	Randomised controlled trial with a sequential trial design
Participants	Location: country Norway but site not clearly identified (maybe Akershus Central hospital, Oslo, Norway) and time of study not stated Included: postpartum women with uterine cramps and possible concomitant episiotomy pain after vaginal birth requesting analgesia Excluded: women allergic to paracetamol
Interventions	Postpartum women with uterine pain and possible concomitant episiotomy pain after vaginal birth and who were asking for analgesic and consented to participate were randomly allocated to 1 of 2 groups: Paracetamol 1000 mg (2 tablets of paracetamol 500 mg) (N = 39) Placebo (2 tablets) (N = 36) The medications were identical in appearance
Outcomes	Pain however measured by the authors: women were asked to rate their pain on a VAS measuring 100 mm at trial entry and again at 2 and 4 hours post‐medication. Uterine cramp pain and episiotomy pain were recorded separately Maternal adverse events: women were asked if they experienced any adverse events, none were suggested to them
Notes	Dates of study: not stated Funding sources: 1st author supported by a grant from the Norwegian Research Council for Science and the Humanities Declarations of interest: declared as none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Study simply described as randomised, but no further details provided
Allocation concealment (selection bias)	Unclear risk	No information related to allocation concealment
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Double‐blind. "Identical appearing tablets."
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	Low risk	1 woman (placebo group) excluded as she had received analgesia 1 hour prior to inclusion. There were 39 women allocated to the paracetamol group and 36 women to the placebo group. Results included for 1 woman in placebo group who was under study when trial stopped. 2 women withdrew after 2 hours observation, no 4‐hour data included. Appropriately‐imputed data were used for women who withdrew before 2 hours
Selective reporting (reporting bias)	Unclear risk	No published protocol or trial registration available
Other bias	Low risk	Similar numbers of women in both groups (10 of the 39 women in the paracetamol group and 11 of the 38 women in the control group) had pain medication before enrolling in the study; inclusion criteria stated that women had pain and were requesting analgesia. Graphs presenting results appear to be mislabelled