Table 1

Methodology of included studies

General information	Study
	1*	2	3
	Martin et al 38	Sarkola et al 40	Terplan et al 41
Type of publication	Peer-reviewed publication	Peer-reviewed publication	Peer-reviewed publication
Research question(s)	To compare treatment continuation and duration (in opioid treatment programmes) before delivery of a live infant in women with UIP vs IP	To identify risk factors for children being placed into out-of-home care	To examine the relationship between pregnancy intention and continued drinking, or binge drinking, in last 3 months of pregnancy
Population	Pregnant women in opioid treatment programme	Pregnant women in specialised AOD antenatal care services (mix of types of AOD)	Postpartum women who drank alcohol in the 3 months prior to pregnancy
Methodology
Study design	Prospective cohort study	Retrospective cohort study	Retrospective cohort study
Study setting	Recruited in antenatal period from AOD treatment clinics	Antenatal datasets and paediatric datasets	Recruited in postpartum period from PRAMS telephone survey
Geographical region	North America (USA and Canada) and Europe (Austria)	Europe (Finland)	North America (33 USA states)
Time period of recruitment	4 May 2005 to 31 October 2008	1992 to 2001	2004 to 2008
Timing of recording of pregnancy intention	During pregnancy	During pregnancy	Retrospective (after pregnancy)
Reporting of AOD use/SUD	Addiction severity index as a measure of impairment. Overall AOD intake not reported	AOD use recorded in maternal records pre-conception, during pregnancy and postpartum. Alcohol use recorded as daily, weekly, less than daily. Opioid use recorded as ‘regular’ (daily or weekly) Urine toxicology results recorded	Self-reported using retrospective recall during the 3 months prior to pregnancy and final 3 months of pregnancy for: Average number of standard alcohol drinks per week drinking Any binge drinking episodes (five or more standard drinks at a time)
Tools used to assess UIP	Non-validated screening questionnaire Categorised: intended/unintended Unintended subgroups: mistimed, ambivalent or unwanted	Dichotomous: intended/unintended	Four-point questions. Reclassified into intended/mistimed or unwanted
Total number of participants	175	626	95 728

*Demographic data obtained from primary study (this study is a secondary analysis).39
AOD, alcohol or other drugs; IP, intended pregnancy; PRAMS, Pregnancy Risk Assessment Monitoring System; SUD, substance use disorder; UIP, unintended pregnancy.