3. Characteristics of included Cochrane systematic reviews ‐ pharmacological interventions.

Review title	Date of search	No. Studies included (No. Patients in included studies)	Inclusion criteria for "Types of participants"	Comparison interventions (no. studies)	Outcomes for which data were reported that could be included in an analysis	Summary of quality of evidence in reviews (risk of bias)
Inhaled analgesia for pain management in labour (Klomp 2012)	7 September 2011	26 studies in 8 countries (USA, Canada, UK, Sweden, Norway, China, Singapore, Iran) between 1969 and 2009 (2967 women)	Women in labour, including high risk groups e.g. preterm labour or following induction	Inhaled analgesia versus placebo control/no treatment (9 studies, 1495 women) Inhaled analgesia versus a different type of inhaled analgesia (14 studies, 752 women) Inhaled analgesia of one strength versus a different strength (2 studies, 625 women) Inhaled analgesia using one type of delivery system versus a different system (2 studies, 75 women) Inhaled analgesia versus TENS (1 study, 20 women)	Pain Intensity Satisfaction with pain relief Assisted vaginal birth Caesarean section Adverse effects for women (nausea; vomiting; drowsiness; dizziness; blood loss; pre‐eclampsia) Adverse effects for infants (hypoxaemia; neuro‐behavioural score; neonatal asphyxia) Admission to special care baby unit Apgar score less than seven at five minutes	Sequence generation: 7 studies low risk; 19 studies unclear risk Allocation concealment: 3 studies low risk; 23 studies unclear risk Blinding (participants & clinical staff): 3 studies low risk; 4 studies high risk; 19 studies unclear risk Blinding (outcome assessor): 3 studies low risk; 4 studies high risk; 19 studies unclear risk Incomplete outcome reporting: 13 studies low risk; 4 studies high risk; 9 studies unclear risk Selective outcome reporting: 16 studies low risk; 5 studies high risk; 5 studies unclear risk Other potential threats to validity: 6 studies low risk; 3 studies high risk; 17 studies unclear risk
Parenteral opioids for maternal pain management in labour (Ullman 2010)	30 April 2011	57 studies in 21 countries (USA, Canada, UK, Italy, Austria, Sweden, Norway, Denmak, Germany, the Netherlands, Turkey, Argentina, Brazil, India, China, Hong Kong, Singapore, Thailand, South Africa, Egypt, Iran) between 1958 and 2010 (7000 women)	Women in labour. Studies focusing specifically and exclusively on women in high‐risk groups, or women in premature labour (before 37 weeks' gestation) were excluded. Studies which include such women as part of a broader sample were included.	Intramuscular (IM) opioid comparisons 16 comparisons (37 studies)   Intravenous (IV) opioid comparisons 7 comparisons (10 studies)   Intravenous patient controlled opioids (IV PCA) 5 comparisons (7 studies)   Opioids versus transcutaneous electrical nerve stimulation(TENS) 1 comparison (3 studies)	Pain Intensity Satisfaction with pain relief Satisfaction with childbirth experience Breastfeeding problems Assisted vaginal birth Caesarean section Adverse effects for women (nausea & vomiting; sleepiness; drowsiness; blood loss) Adverse effects for infants (resuscitation; fetal heart rate changes; respiratory distress; neonatal neuro‐behavioural score; ventilator support) Admission to special care baby unit Apgar score less than seven at five minutes	Sequence generation: 13 studies low risk; 1 study high risk; 43 studies unclear risk Allocation concealment: 17 studies low risk; 40 studies unclear risk Blinding (participants): 22 studies low risk; 6 studies high risk; 29 studies unclear risk Blinding (clinical staff): 22 studies low risk; 6 studies high risk; 29 studies unclear risk Blinding (outcome assessor): 17 study low risk; 5 studies high risk; 35 studies unclear risk Incomplete outcome reporting: 21 studies low risk; 19 studies high risk; 17 studies unclear risk Selective outcome reporting: 1 studies low risk; 3 studies high risk; 53 studies unclear risk Other potential threats to validity: 11 studies low risk; 2 studies high risk; 44 studies unclear risk
Non‐opioid drugs for pain management in labour (Othman 2012)	19 May 2011	18 studies in 7 countries (USA, Canada, UK, Sweden, Argentina, India, China) between 1963 and 2004 (2733 women)	Women in labour, including high risk groups e.g. preterm labour or following induction	Non‐opioid drug versus placebo or no treatment (14 studies, 2003 women) Non‐opioid drug versus any other pain management intervention e.g. opioids (3 studies, 563 women) Non‐opioid drug versus different non‐opioid drug (2 studies, 562 women) Non‐opioid drug versus same non‐opioid different dose (1 study, 28 women) (3 studies have more than two arms and are included in more than one comparison group)	Pain intensity Satisfaction with pain relief Satisfaction with childbirth experience Breastfeeding Assisted vaginal birth Caesarean section Adverse effects for women Adverse effects for infants Apgar score less than seven at five minutes	Sequence generation: 6 studies low risk; 12 studies unclear risk Allocation concealment: 5 studies low risk; 13 studies unclear risk Blinding (participants/clinical staff): 14 studies low risk; 4 studies unclear risk Blinding (outcome assessor): 3 studies low risk; 15 studies unclear risk Incomplete outcome reporting: 16 studies low risk; 2 studies high risk Selective outcome reporting: 12 studies low risk; 5 studies high risk; 1 study unclear risk Other potential threats to validity: 13 studies low risk; 1 study high risk; 4 studies unclear risk
Local anaesthetic nerve block for pain management in labour (Novikova 2012)	6 June 2011	12 studies (countries not stated in review) between 1969 and 2009 (1549 women)	Women in labour, including high risk groups e.g. preterm labour or following induction	Local anaesthetic nerve block versus different dose/agent or timing of anaesthetic nerve block (8 studies, 1120 women) Local anaesthetic nerve block versus placebo (1 study, 200 women) Local anaesthetic nerve block versus opioid (2 studies, 129 women) Local anaesthetic nerve block versus non‐opioid (1 study, 100 women)	Satisfaction with pain relief Assisted vaginal birth Caesarean section Adverse effects for women Apgar score less than seven at five minutes	Sequence generation: 2 studies low risk; 2 studies high risk; 8 studies unclear risk Allocation concealment: 1 study high risk; 11 studies unclear risk Blinding (participants/clinical staff): 4 studies low risk; 4 studies high risk; 4 studies unclear risk Blinding (outcome assessor): 4 studies low risk; 5 studies high risk; 3 studies unclear risk Incomplete outcome reporting: 6 studies low risk; 4 studies high risk; 2 studies unclear risk Selective outcome reporting: 5 studies low risk; 7 studies high risk Other potential threats to validity: 9 studies low risk; 3 studies high risk
Epidural versus non‐epidural or no analgesia in labour (Anim‐Somuah 2011)	31 March 2011	38 studies in 18 countries (USA, Canada, UK, France, Sweden, Finland, Denmark, Mexico, Russia, Saudi Arabia, Egypt, Israel, Iran, India, Taiwan, Thailand, China, Australia) between 1974 and 2010 (9658 women)	Pregnant women in labour requesting pain relief, regardless of parity and whether labour was spontaneous or induced	Epidural versus opioids (33 studies, 8868 women) Epidural versus no analgesia (5 studies, 790 women)	Pain intensity Satisfaction with pain relief Sense of control in labour Satisfaction with childbirth experience Assisted vaginal birth Caesarean section Adverse effects for women (long‐term backache; maternal hypotension; postnatal depression; motor blockade; headache; nausea and vomiting; itching; fever; shivering; drowsiness; urinary retention; malposition; surgical amniotomy) Adverse effects for infants (acidosis; naloxone administration; meconium staining of liquor) Admission to special care baby unit Apgar score of less than seven at five minutes	Sequence generation: 18 studies low risk; 1 study high risk; 19 studies unclear risk Allocation concealment: 16 studies low risk; 22 studies unclear risk Blinding (participants): 4 studies low risk; 6 studies high risk; 28 studies unclear risk Blinding (clinical staff): 4 studies low risk; 3 studies high risk; 31 studies unclear risk Blinding (outcome assessor): 1 study low risk; 1 study high risk; 36 studies unclear risk Incomplete outcome reporting: 12 studies low risk; 7 studies high risk; 19 studies unclear risk Selective outcome reporting: 14 study low risk; 15 studies high risk; 9 studies unclear risk Other potential threats to validity: 18 studies low risk; 8 studies high risk; 12 studies unclear risk
Combined spinal‐ epidural (CSE) versus epidural analgesia in labour (Simmons 2012)	28 September 2011	27 studies in 9 countries (USA, Canada, UK, France, Italy, Belguim, Spain, Saudi Arabia, Brazil) between 1991 and 2009 (3303 women)	Women having combined spinal‐epidural or epidural analgesia commenced during the first stage of labour	CSE versus traditional epidural CSE versus low‐dose epidural	Pain intensity Satisfaction with pain relief Assisted vaginal birth Caesarean section Adverse effects for women and infants Admission to special care baby unit/neonatal intensive care unit Apgar score less than seven at five minutes	Sequence generation: 11 studies low risk; 16 studies unclear risk Allocation concealment: 14 studies low risk; 13 studies unclear risk Blinding (participants/staff/assessors): 15 studies low risk; 3 studies high risk; 9 studies unclear risk Incomplete outcome reporting: 25 studies low risk; 1 study high risk; 1 study unclear risk Selective outcome reporting: 23 studies low risk; 4 studies unclear risk Other potential threats to validity: 3 studies low risk; 4 studies unclear risk (20 studies not assessed)