Preconception Health of Indigenous Peoples in Australia, Canada, New Zealand, and the United States: A Scoping Review

Background: There is increasing recognition of the importance of the preconception period for addressing reproductive and intergenerational health inequities and supporting improved maternal and child health outcomes. This study aimed to understand the extent and type of evidence that exists in relation to preconception health for Indigenous peoples living in high-income countries with similar experiences of colonisation, namely, Australia, New Zealand, Canada, and the United States. Methods: This review was conducted as per the JBI methodology and PRISMA Extension for Scoping Reviews. A comprehensive search of PubMed, CINAHL [EBSCO], Ovid Embase, Scopus, and the Wiley Cochrane Library was conducted using keywords and index terms. We included research in English published between January 2010 and June 2023 on quantitative and qualitative primary studies. Data were extracted using a standardised tool, and the analysis included quantitative descriptions and qualitative content analysis. Results: We identified 360 potential studies and included 57 articles in the review. Most studies were from the United States (n = 36, 63.2%) and Australia (n = 13, 22.8%), and they commonly reported associations between preconception health risk factors and maternal or child health outcomes (n = 27, 48.2%) or described the development, implementation, or evaluation of preconception health interventions (n = 26, 46.4%). Common preconception health areas were pre-pregnancy body mass index or weight (n = 34), alcohol (n = 16), diet (n = 14), physical activity (n = 12), and diabetes (n = 11). Most studies focused exclusively on women (n = 46, 80.7%), and very few included men (n = 3, 5.3%). The study populations were mostly urban and rural (n = 25, 43.9%) or rural only (n = 14, 24.6%); however, the geographical remoteness was often unclear (n = 14, 24.6%). Conclusions: While there was some research relating to the preconception health of Indigenous peoples, this review identified considerable research gaps. There is a need for dedicated research into preconception health risk factors and reproductive health outcomes, attitudes and awareness of preconception health, and preconception health interventions for Indigenous peoples.


Introduction
There is increasing recognition globally of the importance of preconception health in influencing reproductive health outcomes by agencies such as the World Health Organisation [1].The health and behaviours of women and men prior to conception can influence fertility as well as maternal, infant, and child health outcomes.Additionally, early pregnancy is a critical period for foetal development; however, many women will be unaware that they are pregnant in the first few weeks of gestation and continue behaviours that are not recommended in pregnancy [2,3].Several definitions of the preconception period exist, including the biological perspective (i.e., the weeks before embryo development), the individual perspective (i.e., when a conscious decision to conceive is made), and the public health perspective (i.e., longer periods of months or years to address health risk factors) [4].Hill et al. extended this definition to include a life course perspective, which acknowledges that preconception health can be addressed throughout the life course and therefore includes groups such as adolescents and newly sexually active individuals [5].
A range of preconception risk factors have been identified for men and women.Women and men living with obesity have an increased risk of infertility [4], and women living with obesity further have an increased risk of gestational diabetes, pre-eclampsia, obstetric complications, congenital abnormalities, and their offspring living with obesity in childhood [6][7][8].Tobacco, alcohol, and recreational drug use can also reduce fertility in men and women [2,4], and use by women during pregnancy contributes to the risk of obstetric complications, preterm birth, and a low birthweight [6].Maternal alcohol consumption in the weeks prior to and during pregnancy is associated with Fetal Alcohol Spectrum Disorder and birth defects [6].Sexually transmissible infections in women prior to and during pregnancy are also associated with adverse reproductive outcomes [9][10][11].Other preconception factors that can influence reproductive health outcomes include maternal and paternal age, chronic diseases such as type 2 diabetes and hypertension, and environmental exposures [2,6,12].In addition to physical factors, an individual's preconception mental health status can influence pregnancy and birth outcomes [13].
Preconception care is defined as "counselling and the provision of biomedical, behavioural and social health interventions to optimise the health of women and their partners prior to pregnancy and improve health related outcomes for themselves and their children" [3].A recent systematic review found a lack of high-quality clinical guidelines on preconception care and that content on recommended care varied and few recommendations were supported by high-quality evidence [14].Common content areas identified in the review of preconception guidelines were family and reproductive life planning, physical activity, weight and nutrition, chronic and infectious diseases, smoking, alcohol and environmental exposures, and mental health.
Indigenous peoples living in Australia, Canada, New Zealand, and the United States of America share similar colonial histories, as well as contemporary experiences of intergenerational trauma, socioeconomic disadvantage, and racism and inadequate health services [15,16].These experiences have led to similar inequities in relation to a higher prevalence of preconception health risk factors and adverse reproductive health outcomes [17][18][19][20][21][22][23].These adverse outcomes are often exacerbated in rural Indigenous populations who can experience additional barriers to accessing quality, culturally appropriate health care [24].Despite sharing similar experiences, there is considerable heterogeneity of Indigenous populations living within these four countries, with unique histories, languages, and cultural practices.Additionally, each country has a unique health system and approach to providing health services for Indigenous peoples [25].
Given the increasing acknowledgement of the importance of the preconception period and health for addressing reproductive and intergenerational health inequities, there is value in synthesising the available evidence relating to the preconception health of Indigenous peoples, including how Indigenous Australians understand preconception health, interventions to support Indigenous Australians' preconception health, as well as the access to and uptake of preconception care.As such, the aim of this scoping review is to assess the extent of the literature relating to the preconception health of and preconception health interventions for Indigenous peoples living in Australia, New Zealand, Canada, and the United States.

Search Strategy and Selection Criteria
A scoping review was conducted as per the JBI methodology [26] and PRISMA Extension for Scoping Reviews (PRISMA-ScR) [27].A scoping review is a transparent, rigorous, and structured method to synthesise and analyse published research and to identify evidence gaps [28].
A comprehensive search strategy was developed in PubMed and CINAHL [EBSCO] using a combination of keywords and index terms used in relevant previous reviews [29 -32] (File S1).The search strategy was adapted for additional databases: Ovid Embase, Scopus, and the Wiley Cochrane Library.
This review included studies relating to the preconception health of Indigenous peoples living in Australia, New Zealand, the United States, and Canada, with a focus on the following:

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The association of preconception health risk factors with fertility, maternal health outcomes (i.e., during pregnancy, birth, and the postnatal period), and child health outcomes; Studies were included if they focused on Indigenous peoples or reported results separately for Indigenous peoples.Indigenous peoples were included as recognised by each country and included Aboriginal and Torres Strait Islander peoples in Australia, First Nations, Inuit, and Metis peoples (also known as Aboriginal peoples) in Canada, Māori people in New Zealand, and American Indians and Alaska Natives in the United States.While the population of interest was Indigenous women and men, studies with other participant groups were included if the focus was on Indigenous preconception health (e.g., health professionals, elders, and community members).Given variations in definition of the preconception period and the exploratory aim of this review [4,5], the preconception period was defined by the study under review.Studies were excluded if data relating to the preconception period could not be disaggregated from data during or after pregnancy.Dorney et al.'s [14] review of preconception clinical guidelines was used as a framework to identify preconception health risk factors that were eligible for inclusion.Research which focused on health risk factors more generally without specifying their relevance to the preconception period was not included.Research which reported the prevalence of a preconception health risk factor (and predictors of prevalence) without exploring the relationship with pregnancy, birth, or child health outcomes was excluded.Finally, while planned pregnancy is an important element of preconception health care [33,34], studies which focused exclusively on contraception were excluded, as this was not a focus of the review.
Quantitative (experimental, quasi-experimental, and observational) and qualitative primary research studies published in English from 2010 to 25 June 2023 were included.This timeframe was selected to ensure recency of findings and also aligns with an emerging global focus on preconception health [1].Systematic and narrative reviews, commentaries, and clinical guidelines were excluded; however, the reference lists of relevant reviews were searched.Conference abstracts, study protocols, and dissertations were excluded.
Two reviewers (CW and TB) independently screened all citations, abstracts, and full-text data, with any disagreements about study selection resolved via discussion or in consultation with a third reviewer (FB).The reference list of all included sources of evidence was also screened for additional studies.

Data Extraction and Analysis
Data were extracted using a standardised tool by one reviewer (CW) and verified by a second reviewer (FB).Information was extracted about study design, setting and population, the areas of preconception health focused on, and key results.Preconception health areas were reported if they were identified as a focus of the study or intervention for Indigenous peoples, regardless of whether data could be extracted for the purpose of this review.Where possible, the geographical remoteness of study participants was identified and classified into 'urban', 'rural', 'urban and rural', or 'not stated/unclear' using each country's standard geographical remoteness classification system [35][36][37][38], or the authors' description of remoteness was used if a study location was not named.For studies reporting associations between preconception health risk factors and reproductive health outcomes, the association that adjusted for the greatest number of confounders was reported; however, studies were not excluded if only unadjusted analysis for Indigenous peoples was presented.
Given the aim of the study and the broad scope of methodologies accepted, no quality assessment was performed on eligible studies.
The characteristics of the 57 included studies were summarised with frequencies and proportions using Microsoft Excel.Inductive content analysis was conducted on qualitative data to identify common themes across studies [39].

Search Results
Electronic database searches identified 709 titles and abstracts.After removal of duplicates, 360 articles were screened by title and abstract, resulting in 112 potential articles for inclusion.After reviewing the articles' full texts, 47 studies were included.An additional 10 studies were identified from reviewing the reference lists of the includes studies, leading to a total of 57 studies being included in this review (Figure 1).
Studies mostly reported associations between preconception health risk factors and maternal or child health outcomes (n = 27, 48.2%) or described the development, implementation, or evaluation of preconception health interventions (n = 26, 46.4%) (Tables 2 and 3).Fewer studies described Indigenous peoples' uptake of preconception health care, including factors affecting the uptake of preconception health interventions and care, or Indigenous peoples' or health professionals' knowledge and attitudes towards preconception health (n = 4, 7.0%) (Table 4).
Almost all study populations were exclusively women or young women (n = 46, 80.7%), while only two studies included men and women (3.5%).Eight studies (14.0%) included health professionals, elders or community members as participants, or a combination of these groups and women.One study included health professionals, men, and women (1.8%).
Study populations were mostly urban and rural (n = 25, 43.9%) or rural only (n = 14, 24.6%).Few studies were urban only (n = 4, 7.0%), and in a quarter of studies, the geographical remoteness of the population was not stated or unclear (n = 14, 24.6%).Abbreviations: CI = confidence interval, SD = standard deviation, OR = odds ratio, AOR = adjusted odds ratio, APR = adjusted prevalence ratio, ARR = adjusted relative risk, HR = hazard ratio, GDM = gestational diabetes mellitus, GWG = gestational weight gain.BMI categories are defined as follows: underweight = <18.5,normal weight = 18.5-24.9,overweight = 25-29.9,class I obese = 30-34.9,class II obese = 35-39.9,class III obese = 40+.At baseline, mothers had greater knowledge (measured as a percentage of questioned answered correctly) of GDM prevention than their daughters (mean score on a 0 to 100 scale: mothers 49.2, SD 20.9, daughters: 20.9, SD 20.4,p < 0.001) and perceived greater susceptibility than their daughters (mean score on a 0 to 20 scale: mothers 8.9, SD 4.0, daughters 7.0, SD 3.8, p < 0.001).Daughters reported moderate levels of self-confidence (self-efficacy) in their ability to engage in healthy living (mean score on an 8 to 80 scale: 48.2, SD 13.9) but low mean scores on healthy eating (mean score, 9.0, SD 5.6) and physical activity (mean score: 3.4, SD 2.2).Mothers were more likely to initiate GDM communication with daughters than vice versa (mean score: mothers 2.9, SD 0.9, daughters 2.3, SD 1.3, p < 0.001) The proportion of participants at risk of alcohol-exposed pregnancy reduced from 54% at baseline to 20% at 12 months (difference between baseline and all other visits p < 0.001).Alcohol consumption decreased across all behavioural measures over the intervention duration (average change −26% to −17%, 99% CIs −41% to −7%), and the proportion of participants reporting no birth control decreased from baseline to 3 months (29-10%, p < 0.001).In total, 121/177 (68%) of confirmed pregnancies had received preconception care prior to the pregnancy.Sexually transmissible infection screening (71%) was the most common care delivered, followed by folic acid prescription (57%) and smoking cessation support (43%).Nutrition and weight (36%), alcohol and illicit substances (26%), chronic disease management (17%), and vaccinations (12%) were less common preconception care interventions.Preconception care was usually patient-initiated (63%), conducted by a nurse or Aboriginal Health Worker (59%) and increased significantly over the audit period (number of consultations p = 0.003).There were no differences in the likelihood of receiving preconception care by age group, pregnancy outcome, gestation at first antenatal visit, parity, diabetes or albuminuria status, BMI, or smoking behaviour.Younger women were less likely to be screened for chronic diseases (linear trend across age groups p < 0.01).
Two studies found associations with a history of depression pre-pregnancy [54] or a history of treatment or check-up for depression [82] and postpartum depression.One study found an association between chlamydia and/or gonorrhoea before pregnancy and miscarriage [10].
Eight studies focused on interventions to prevent gestational diabetes and therefore referred to BMI, healthy eating, and physical activity preconception health risk factors [80,81,83,88,89,92].One quantitative study found that the mean knowledge and selfefficacy increased post-intervention [83], and another found an increase in certain healthy eating behaviours compared to the control group post-intervention [90].Three studies focused on mandatory bread fortification with folic acid and/or iodine [40,57,58].An Australian study found an increase in red cell folate and reduced Neural Tube Defects post-fortification [40], while a New Zealand study modelled that folic acid fortification would result in insufficient additional dietary folic acid [57].Mandatory iodine fortification in New Zealand was found to reduce the proportion of women consuming insufficient iodine [58].One intervention focused on improving individuals' preconception diet and demonstrated a positive impact on Vitamin A and D consumption but no reduction in energy, sugar, or fat [52].Another intervention focused on preconception health education more generally and found improvements in knowledge post-intervention [84].

Studies Describing Uptake of Preconception Care and Preconception Health Knowledge and Attitudes
Several studies reported on women's access to preconception health information and/or care (Table 4) [44,76].Other studies focused on specific topics or health conditions such as folic acid information [96] and women with heart disease receiving preconception counselling [59].One study reported on young peoples' knowledge and attitudes to preconception health and co-designed a resource that is available in print or electronically [43].

Discussion
This scoping review aimed to assess the extent of the literature relating to the preconception health of Indigenous peoples living in Australia, New Zealand, Canada, and the United States.The study identified a range of research which focused on the preconception health of Indigenous peoples, particularly from the United States and Australia.There was a range of evidence in some areas of preconception health, notably studies exploring associations between BMI and maternal health outcomes and, to a lesser extent, interventions focusing on a single preconception risk factor or outcome.There were notable differences in the areas of preconception health that was focused on by country, which may reflect variances in Indigenous populations as well as differing policy priorities.However, the review identified significant gaps in the literature relating to the preconception health of Indigenous peoples, including studies focusing on preconception health risk factors other than BMI and culturally appropriate preconception care interventions, as well as studies which focus on men as participants.Additionally, there was a lack of studies exploring Indigenous peoples' knowledge and attitudes relating to preconception health, the uptake of preconception health interventions, and barriers and enablers to preconception care.Due to the variability in quantitative studies, including exposures, interventions, and outcomes, it was not possible to conduct any meta-analysis on the identified studies, and it is not recommended that a systematic review is conducted at this time.
Beyond the evidence relating to BMI and pre-pregnancy diabetes, the review found a lack of evidence on the associations between preconception health risk factors and maternal and child health outcomes.There are substantial risks associated with women who are either underweight or overweight prior to pregnancy, and as such, BMI is a focus of the broader preconception health epidemiology literature [4,97].Indigenous women are overrepresented in both underweight and overweight categories, thereby warranting a strong focus on BMI as a preconception health risk factor [17,98].Additionally, Indigenous women have a higher prevalence of pre-pregnancy diabetes, which is associated with adverse maternal and perinatal outcomes [23].However, there are other preconception health risk factors which disproportionately affect Indigenous peoples and were missing from the epidemiological literature, such as tobacco use, physical inactivity, at-risk alcohol use, sexually transmissible infections, and psychological distress [19,20,22,99].These are all factors that are described in various preconception guidelines [14] and have been linked to the ongoing impacts of colonisation and inequity in access to health care.Population-wide preconception health studies should be sufficiently powered where possible to facilitate stratified analysis of Indigenous participants.Studies should also disaggregate preconception and antenatal risk factors when collecting and analysing data, so that the relative impact of these two time periods can be better understood.Additionally, many studies were retrospective and thus often limited, by design, in terms of the availability of data on preconception care.Future studies should be prospective and specifically designed to gather direct and rigorous information on preconception care and preconception care services.
Given the cultural diversity of Indigenous peoples and identified barriers to accessing health care, there is a need for additional research into Indigenous peoples' knowledge and attitudes relating to preconception health, uptake of preconception health interventions, and barriers and enablers to preconception care.These studies are important to inform the development of culturally appropriate interventions and policies to support Indigenous peoples' preconception health.Similarly, there is a need for research to understand health professionals' understandings and perspectives of delivering preconception care for Indigenous peoples to identify health system factors that support and hinder preconception care [100,101].
Despite the opportunity that the preconception period poses for improving maternal and child health outcomes, there remains a lack of interventions that can optimise preconception health factors for Indigenous peoples at an individual and population level across the life course.This is similar to the lack of preconception health interventions and high-quality evaluation of efficacy in the general population [102].While this review identified a number of intervention studies, most focused on single preconception health factors, predominantly alcohol and folic acid/iodine fortification, as well as gestational diabetes prevention.There is benefit in designing and rigorously evaluating interventions for Indigenous peoples which address multiple preconception health risk factors in a holistic and culturally appropriate manner.The review identified a number of common themes relating to the development, implementation, or evaluation of preconception health interventions, including the role of family, community, and/or culture in promoting positive health behaviours [63,65,74,77,81,88,92]; the importance of culturally appropriate content [65,68,[79][80][81]92]; and the importance of a strength-based or empowerment approach [68,80].While these themes are supported by the broader literature on creating culturally appropriate health interventions for Indigenous peoples [103][104][105], preconception health interventions need to also ensure that Indigenous peoples are actively involved in every stage of program development and delivery.Additionally, interventions need to be holistic and based on a socio-ecological model that addresses the broader determinants of health at the individual, community, system, and policy levels.There is also value in prioritising the cultural determinants of health as part of an empowerment approach to optimising preconception health.
As with the literature on preconception health more generally [106], the identified studies almost all focused exclusively on women.Given the evidence that certain preconception health risk factors in men such as living with obesity and smoking can influence reproductive health outcomes [2,107], as well as the potential influence of men on their partners' health [108], there is a need for a greater focus on men's preconception health, including their knowledge on and attitudes to preconception health.Although this study did not focus primarily on fertility and infertility, there is a strong link between a range of preconception health risk factors and adverse fertility outcomes for both men and women [2,7].Few studies reported fertility as a study outcome or content in preconception health education interventions.Future research on preconception health should consider including fertility as a reproductive health outcome, and qualitative research should also explore Indigenous peoples' awareness of preconception health factors that influence fertility for men and women.
As with other social determinants of health, geographical remoteness is an important predictor of health outcomes in the countries studied [109].While rural and remote populations are more likely to experience adverse health outcomes, health inequities persist in increasingly urbanised Indigenous populations [24].However, many of the studies included in this review did not specify the geographical remoteness of participants, and rurality was infrequently included in analysis.A greater focus on the rurality of participants would assist in understanding the relative importance of geographical rurality in preconception health and health care access, and information on the geographical context of interventions may assist with the transferability of interventions.
As an exploratory scoping review, this study had several limitations.Firstly, the broad inclusion criteria led to some challenges in the study selection; however, any discrepancies between reviewers were resolved through discussion and, when necessary, a third reviewer.Nevertheless, it was necessary to place some limitations on the types of studies included, which may have skewed the study results.For example, only studies which separated out data on Indigenous peoples were included, which meant that New Zealand studies which combined Māori and Pasifika populations, and Hawaii-based studies which combined Native Hawaiian and other Pacific Islander populations, were excluded.
Similarly, studies which combined data on preconception and pregnancy risk factors were excluded, leading to the exclusion of studies focusing on key preconception risk factors such as tobacco, alcohol, and other drugs and mental health.Finally, studies which only reported the prevalence of a preconception risk factor without exploring the relationship with pregnancy, birth, or child health outcomes were excluded.These studies are a useful component of the evidence relating to preconception health, although data on the prevalence of many of these preconception health risk factors in Indigenous populations of reproductive age are available in government publications [19][20][21]110].
Additionally, the study did not review grey literature, which may have led to some preconception interventions being missed.Nevertheless, the study provides the first ever review of the preconception health of Indigenous peoples and identifies a range of priorities for further research on this important topic.

Conclusions
In conclusion, this study identified some evidence and considerable gaps in the literature relating to the preconception health of Indigenous peoples living in Australia, New Zealand, Canada, and the United States.Given the increasing acknowledgement of the importance of the preconception period for addressing reproductive and intergenerational health inequities, and for improving maternal and child health outcomes, there is a need for dedicated research into the preconception health risk factors and reproductive health outcomes, attitudes towards and awareness of preconception health, and preconception health interventions for Indigenous peoples.

Author Contributions:
All authors (C.W., T.B., J.A.B., J.W. and F.B.) contributed to the design and conceptualisation of the study.C.W. searched the databases.C.W., T.B. and F.B. contributed to the screening of studies for inclusion and data extraction.C.W. and F.B. contributed to the analysis and interpretation of the data.All authors contributed to the writing or editing and reviewing of the manuscript.All authors have read and agreed to the published version of the manuscript.

Table 1 .
Summary of included studies.

Table 2 .
Studies on associations between preconception health risk factors and maternal or child health outcomes.Other preconception health risk factors were not associated with diabetes in pregnancy.

Table 2 .
Cont.There was no association between hip circumference, waist-to-hip ratio, or waist-to-height ratio and gestational hypertensive disorders.

Table 3 .
Studies describing development, implementation, or evaluation of preconception health interventions.

Table 4 .
Studies of uptake of preconception care and preconception health knowledge and attitudes.