The systematic review has been registered with the International Prospective Register of Systematic Reviews (PROSPERO; registration number: CRD42018095315). The review protocol was reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol (PRISMA-P) recommendations (41) (Appendix 1). The methods are consistent with those recommended by the Cochrane Handbook for Systematic Reviews of Interventions Version 6.0 (42).
Outcomes
The primary outcomes of the review are pregnant women’s SNAP behaviour outcomes: tobacco smoking, nutrition intake, alcohol consumption, and physical activity. The secondary outcomes are maternal and/or child health outcomes, and any unintended consequences or adverse outcomes of the intervention.
Search strategy
Electronic bibliographic databases will be searched for eligible peer reviewed literature, including: Medline (Ovid), EMBASE (Ovid), PsycINFO (Ovid), Maternity and Infant Care (Ovid), Scopus, CINAHL (EBSCOhost) and Cochrane Library (Wiley). The reference lists of all included studies will be screened for other potentially eligible studies. The search strategy will be developed in consultation with a research librarian. There will be no restrictions on the length of the study follow-up period, country of origin, or year of study. Only studies published in English will be eligible for consideration.
The strategy will include search terms for participant, intervention, comparator, outcome and study design. The database search term strategy for Medline is described in Appendix 2. The search strategy will be adapted for other databases using appropriate syntax and terminology developed in consultation with a research librarian.
Eligibility criteria
Participants: Studies of pregnant women receiving antenatal care at any time during pregnancy will be included. Studies of women in preconception or postnatal periods are not eligible for inclusion. Studies with interventions that span pregnancy and preconception or postnatal periods will be included only when intervention details and behavioural outcome data is outlined separately for the pregnancy period.
Interventions: Studies that include any intervention delivered during antenatal care, or instigated in antenatal care (e.g. referral to another health service for support), that aims to address multiple health behaviours (i.e. more than one SNAP behaviour) during pregnancy will be included. This includes all care provided or instigated in the antenatal care setting regardless of which health professional provided the care (e.g. antenatal clinician or health professional employed as a research personnel to provide care within the study). Antenatal settings can include primary care, hospital antenatal clinics, community antenatal clinics, home antenatal clinics, private obstetrics, midwifery care or allied health services. Studies with interventions that are in settings that are not usual health care providers to women during pregnancy, such as mass media health education campaigns, will be excluded. SNAP health behaviours include: tobacco smoking, nutrition, alcohol consumption and physical activity. The intervention could include, but are not limited to: assessing pregnant women’s health behaviour/s through validated and objective instruments, or self-reported behaviours; advising women on the health behaviour recommendations and providing education on the risks associated with adverse SNAP health behaviours during pregnancy; and providing behavioural support directly or offering a referral to other allied health and specialist services for additional support.
Comparator: Studies will be included that compare a multiple health behaviour intervention with no intervention control, wait-list control, usual care, or another active intervention addressing one health behaviour (e.g. alcohol only).
Outcomes: Studies that include any measure of pregnant women's modifiable health behaviours, including tobacco smoking and/or cessation, nutrition intakes (e.g. reported as dietary intakes for energy, macronutrients or micronutrients; adherence to food or nutrient guidelines; or overall diet quality scores), alcohol consumption and/or abstinence, and physical activity will be included. Outcome data can be collected via any data collection method (e.g. self-report, observation, or objective measures) including audits of service or medical records such as patient pregnancy records.
Types of studies
Systematic review of randomised controlled trials (RCTs), RCTs, cluster RCTs, stepped-wedge RCTs (or stagged enrolment trials), and non-randomised controlled trials will be eligible for inclusion. Studies with designs without a parallel control group or another active intervention addressing one SNAP health behaviour (e.g. pre-post studies or historic control groups) will be excluded.
Data collection and analysis
Study selection
The titles and abstracts identified through the search strategy will be screened for eligibility by two independent reviewers using the eligibility criteria above. Studies that do not meet the criteria will be excluded. The full texts of all remaining studies will be reviewed by two independent reviewers, and the reason for exclusion will be recorded. Any discrepancies regarding study eligibility will be resolved through discussion and consensus between the two reviewers, or if required, consultation with a third reviewer. A reviewer will contact the study authors for clarification where there is insufficient information to determine study eligibility. If sufficient information is still unavailable, the study will be excluded from the review. Screening will be managed in Covidence (www.covidence.org).
Data extraction
Data from the eligibile studies will be extracted by one reviewer and confirmed by a second reviewer. Data will be extracted using a standardised electronic form consistent with data collection items recommended by the Cochrane Handbook for Systematic Reviews of Interventions (42). The form will be piloted prior to use. Any discrepancies in data extracted will be resolved by consensus between the two reviewers, or consultation with a third reviewer if required. Reviewers extracting data will not be blind to author or journal information.
The following information will be extracted:
- Study characteristics: authors (including contact details); article citation; date of publication; country of study; aim of study; dates intervention undertaken; participant characteristics (i.e. number of participants, age, body mass index, ethnicity, sociodemographic information, parity, clinical conditions, weeks’ gestation); sample size; missing participants; study design; number of experimental groups; antenatal service setting (e.g. primary care, hospital antenatal clinics, home visit antenatal services, or allied health); and information to assess risk of bias.
- Intervention characteristics: SNAP behaviour change targeted; duration of intervention; number of contacts; theoretical underpinning of intervention and comparator; intervention content; mode of delivery (e.g. individual or group, in-person, online, telephone); profession of intervention deliverer (e.g. midwife, obstetrician, dietitian, general practitioner, researcher).
- Outcomes: SNAP behaviour outcomes (smoking, nutrition, alcohol, physical activity) including definitions; maternal and/or infant health outcomes (i.e. health outcomes measured such as gestational weight gain, gestational diabetes, gestational hypertension, pre-eclampsia, preterm birth, low birth weight, macrosomia, fetal alcohol spectrum disorder, and child and maternal obesity) including definitions; duration of follow-up; data collection method; name of tool; validity of measures used; scale of measure; number of participants per comparison group at each time point; effect size and measures of outcome variability.
- Other: Key conclusions of the study authors; any unintended consequences or adverse outcomes; sources of funding; any potential conflicts of interest.
Assessment of risk of bias
The risk of bias of the included studies will be assessed by two independent reviewers for both primary and secondary outcomes. The Cochrance Risk of Bias Tool, RoB2, (42) will be used to assess study characteristics for each RCT that is included in the review, including: i) bias from the randomisation prcoess, ii) bias from deviations from intended interventions, iii) bias from missing outcome data, iv) bias in the measurement of the outcome, v) bias in the selection of the reported results. An additional criteria will be used to assess risk of bias in cluster RCTs: vi) bias arising from identification or recruitment of individual participants within clusters (42). For included studies of non-randomised trial design, risk of bias will be assessed using the Newcastle-Ottawa Scale (NOS): i) selection, ii) comparability, iii) outcome (43). A consensus approach between the two reviewers will be used to resolve any assessment discrepancies, or a third reviewer with expertise in review methodology will be consulted.
GRADE
The GRADE approach (44) will be used to assess the overall quality of the evidence for the each of the four behavioural primary outcomes. Two independent reviewers will conduct the assessment, with discrepancies resolved through discussion and consensus between the two reviewers, or consultation with a third reviewer. Quality ratings ranging from ‘very low’ to ‘high’ will be assigned to each study.
Measures of treatment effect
Where possible, trial data will be combined and reported using meta-analyses using the standard estimation of: 1) risk ratio (RR) and 95% confidence intervals (CI) for dichotomous outcome variables, and 2) mean differences (MDs) or standardised mean differences (SMDs) and 95% CIs for continuous outcome variables. We will use SMDs when studies report the same outcome and a comparable, but not identical, measure. In instances where a meta-analysis is not appropriate, alternative synthesis methods will be investigated as recommended by the Cochrane Handbook for Systematic Reviews of Interventions (42), such as summarising effect estimates, combining P values, vote counting based on direction of effect, or synthesis in narrative form.
Unit of analysis issues
We expect to identify individually randomized and cluster‐randomized studies for this review. We will examine cluster trials for unit of analysis errors. Where unit of analysis errors are identified, we will attempt to correct them prior to including the data in pooled analyses. For cluster design trials, individual level behaviour data adjusting for clusters using an intracluster correlation co-efficient (ICC) will be extracted. Study authors will be contacted to provide the ICCs for trials where the effects of clustering have not been reported. Where study authors are unable to provide ICCs, a mean ICC will be estimated from reported ICCs of included studies with similar behavioural outcome data and used to calculate effective sample sizes.
Dealing with missing data
Study outcome data analysed using the intention to treat (ITT) principle will be preferentially extracted over other outcome data (e.g. analysed using a completer’s analysis), unless no ITT data is available. We will contact study authors to obtain missing data where it occurs. We will conduct sensitivity analysis excluding trials with high levels of missing outcome data (>30%).
Assessment of heterogeneity
Heterogeneity of included studies will be examined using visual inspection of forest plots and statistically quantified by calculating the I² statistic (42). An I² statistic of > 50% is considered to be substantial heterogeneity. We will perform subgroup analyses to identify the source of heterogeneity in such circumstances. Consensus will be sought between review authors regarding the appropriateness of a meta-analysis (42).
Data synthesis
Data from randomised and non-randomised study designs will be synthesised separately. Outcomes will be reported by intervention characteristics. If included studies are considered sufficiently homogenous, the primary and secondary outcomes will be combined in a meta-analysis using a random effects model, and reported as a RR, MD and SMD. Alternative synthesis methods will be conducated as recommended by the Cochrane Handbook for Systematic Reviews of Interventions (42) if studies cannot be combined in a meta-analysis.
Where studies report multiple of the same behavioural outcomes (e.g. for smoking cessation) using different data collection methods (e.g. self-report measures by women, health professional self-report, researcher observations or medical record audits), the outcome that is deemed to represent the most valid measure and/or for which the longest follow-up or most complete data is reported will be used. Only intervention and control groups that meet the eligibility criteria from multiple arm studies will be included in data synthesis. If a study contains multiple intervention or control arms that are all eligible for inclusion, a decision will be made to either i) collapse all intervention and/or control arms into single pair wise comparisons or ii) conduct bivariate analyses with all eligible arms included and adjust for the repeated inclusion of the same intervention and/or control arm.
Assessment of reporting biases
The methods and analyses of published studies will be compared to trial protocols and registers to identify instances of potential selective reporting. Funnel plots will be generated for each outcome to determine potential publication bias for meta-analyses including 10 or more studies.
Sensitivity analysis
Sensitivity analyses will be conducted for each of the SNAP behaviour outcomes where there are sufficient studies. This will be performed by removing studies with an overall high risk of bias to examine their impact on the effect estimate.