We used the following keywords: “preconception” AND “content” AND “adult(s) OR adolescent(s)” in the following electronic databases: Cochrane Library, PubMed, Science Direct, CINAHL/EBSCO, and ProQuest. The researchers set several inclusion criteria for the selection of research articles. The criteria stipulated that (1) the type of research was qualitative, quantitative, or mixed-methods; (2) the participants in the included studies were predominantly female adolescents and or reproductive-aged adults (aged 15-49 years) following the World Health Organization (WHO) standard for PCC target groups [2]; (3) the studies were published in English; (4) the studies were published within the past decade (January 2012 to March 2022); and (5) the outcomes included PCC knowledge and information. Studies on participants with preexisting conditions, such as chronic illnesses, were excluded if no full text was available. With these keywords, we found 1,230 articles in April 2022. After deleting 987 duplicates and 131 non-full-text articles, 112 articles were selected and read. During the reading, 104 articles were excluded as they did not meet the article selection criteria (e.g., guidelines, protocol articles) (Figure 1). Finally, eight studies [12-19] were included in this review study.

The 16-item Quality Assessment Tool for Studies with Diverse Designs (QATSDD) by Sirriyeh et al. [20] was used to scrutinize the quality of the selected studies. The reliability and validity of the papers were checked, and rigor was evaluated when choosing these qualitative and quantitative studies. All items of the QATSDD can be used for mixed-method research studies, while 14 items can be used for the quality assessment of quantitative and or qualitative studies. Each included paper was checked individually and assigned a score of 0 (=not at all), 2 (=very slightly), 3 (=moderately), or 4 (=complete) according to the identified criteria. The quality appraisal was presented as a percentage of the maximum possible score (42 for both qualitative and quantitative studies) and was generated from the scores given and agreed upon by the first and second authors to establish interrater reliability. A higher score indicated better quality of the paper. Any disagreements about the percentage were resolved through discussion, and when necessary, the third and fourth authors were involved in resolving the disagreement. The assessment results are presented in Table 1.

To summarize the results in a logical way that aligns with the aim of this review, we used a chart to extract key information on the selected articles, including the author’s name, the year and country of the study, the study type and sample, the study’s aim, the article’s quality score by QATSDD, and thematic findings (Table 1). Next, the review was structured by transforming the qualitative or quantitative data from the eligible studies into integrated themes. In the synthesis phase, the authors generated broader themes by reviewing, comparing, and contrasting the different perspectives regarding PCC knowledge and modes of information delivery from the eight selected articles. The integrated themes were formulated to respond to the aims of this scoping review [21].

As can be seen in Table 1, all included articles were from 2018 and beyond, and four were from 2021. Of the eight selected studies, five were conducted in low- to middle-income countries (Ethiopia, Indonesia, India, and Nigeria) [13,15,17-19], and three were from high-income countries (the United States, Japan, and Australia) [12,14,16]. These findings indicated the increased interest in PCC research following a better understanding of PCC’s importance for women’s and children’s health across the globe. Seven studies were quantitative, including one randomized controlled trial (RCT) [12], one quasi-experimental study [13], one longitudinal intervention [14], and four cross-sectional studies [15-18], while there was one descriptive qualitative study [19]. The studies involved 2,023 female adolescents and reproductive-aged adults attending health care services or at community sites.

As noted in Table 1, all studies in this review described some levels and types of basic knowledge regarding PCC, and the details were closely related to the country’s income classification. For instance, in low- and middle-income countries, such as Nigeria, only a few women had good PCC knowledge [18]. Although research in Ethiopia showed that many pregnant women understood human immunodeficiency virus screening, family planning, and hypertension screening, only a few were aware of folic acid and iron consumption and hepatitis B screening, as PCC information was usually provided by health workers only during antenatal visits [17]. A qualitative study in India also reported that of 76 women (aged 15 to 39 years) who participated in focus group discussions, most were well acquainted with the basic concepts of PCC, such as nutrition pre-pregnancy and the effects of tobacco and alcohol effects, but only a few were aware of the need of good mental health, PCC programs, sexually transmitted infections, and the effect of chronic medical conditions; furthermore, 50% had an unplanned pregnancy and most did not access PCC services [19].

On the contrary, research in the United States, as a high-income country, reported that half of the young women had basic PCC knowledge, including treatment goals, the urgency of care, folic acid supplementation, genetic counseling, iron supplementation, and family planning [12]. Meanwhile, an Australian study stated that the adolescents understood well the general health information related to PCC and pregnancy planning [16]. Last, a study in Japan indicated that the female respondents had broader knowledge about PCC, as the study also mentioned cancer screening, infertility, and rubella prevention [14]. These studies indicate that adolescent girls and women in higher-income countries are equipped with more extensive information on PCC.

The prevailing method utilized in providing PCC information was direct health promotion through face-to-face meetings with the female respondents; this method was described in four studies [13-15,18]. For example, a PCC information session delivered through a conventional face-to-face individual health education in the Office of Religious Affairs in Indonesia demonstrated significant effectiveness in changing women’s knowledge regarding physical health, nutrition, and lifestyle [13]. Meanwhile, PCC information group seminars in Japan were conducted through face-to-face individual education, which effectively improved women’s knowledge of preconception nutrition, lifestyle, and physical health [14].

In addition to documenting more extensive PCC knowledge, attitudes, and practices, two studies conducted in high-income countries [12,16] reported advanced modes of PCC information delivery. Those studies reported that PCC information was delivered through digital technology, including web-based PCC educational media [12] and social media (Facebook, Instagram, Snapchat, etc.) [15,16]. An RCT in the United States reported that young women who received an automated PCC intervention from embodied web-based PCC counselors for 12 months showed an enthusiastic attitude toward accessing information that increased their PCC knowledge [12]. Adolescent girls and women utilized internet applications as a source of information related to PCC, and most shared PCC information with others [12,16]. Furthermore, some research indicated that healthcare workers played minimal roles as the source of PCC information for women in Nigeria and Ethiopia [15,18], and PCC services provided by healthcare providers might encourage women’s involvement in PCC, including screening for risk factors and genetic disorders [14,22].