Martin 2001.

Methods	Randomised controlled trial conducted in Alachua County Public Health Unit, Gainseville Florida, USA.
Participants	42 women participated in this trial 22 in the intervention group and 20 in the control group. Inclusion criteria: "teenage patients (18 years or younger at the time of conception)... before the end of their 24th week of pregnancy".
Interventions	Experimental group received "childbirth preparation in self‐hypnosis that incorporated information on labour and delivery". Control group received "supportive counselling designed to control for interpersonal contact and social support and to provide an opportunity for discussion about pregnancy issues of concern to the patient". A retrospective comparison group of 24 women who received no specialised training was included in the study but has not been considered as part of this review as the women were not randomly assigned to the comparison group. The intervention was a 4‐session sequence provided to women on a 1‐to‐1 basis.
Outcomes	Caesarean section; spontaneous vaginal birth; assisted vaginal birth; admission to SCBU/NICU; number of maternal days in hospital after the birth; use of pharmacological pain relief, induction or augmentation with Pitocin.
Notes	Information requested: email sent to authors requesting additional information on methods and clarification on definitions for outcomes (types of surgical intervention; complications; reason for hospital stay). No response to date but a copy of the PhD thesis reporting on the study has been obtained.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	“randomly assigned”
Allocation concealment (selection bias)	Unclear risk	Not reported.
Blinding of participants (objective outcomes)	Low risk	“Both groups of patients received the standard prenatal treatment protocol from the medical staff, nurse practitioners, and hospital staff, all of whom were blind to group assignment.”
Blinding of participants (subjective outcomes)	Unclear risk	Women not told their group allocation but there was no reporting about whether blinding was successful.
Blinding of personnel (performance bias)	Low risk	“Both groups of patients received the standard prenatal treatment protocol from the medical staff, nurse practitioners, and hospital staff, all of whom were blind to group assignment.”
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Complications and other data “were entered in subjects’ records by obstetric staff who were unaware of the study."...“Statistical analysis was based on a simple count of the presence or absence of complications in the medical record by researchers (the researchers were not blinded to the patient’s study assignment)" not clear who made outcome assessment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	5 participants chose not to participate in the study prior to randomisation. Following randomisation there was a loss of 5 participants (3 moved out of the area before the birth and 1 from each group did not complete the research protocol) ‐ losses seem fairly balanced between groups and not likely to be related to the intervention.
Selective reporting (reporting bias)	Low risk	All prespecified outcomes reported upon.
Other bias	Low risk	"There were no statistically significant differences between the groups for racial group and relationship status, the groups were also comparable for age, educational background and parity."