Trends, collaboration, and impact of scientific research on the Mediterranean diet during pregnancy

Abstract

BACKGROUND:

The Mediterranean diet (MED) is well recognized for its general health benefits and, specifically, during pregnancy, where it may reduce risks such as gestational diabetes, intrauterine growth restriction, preterm birth, and low birth weight. It is also associated with improved maternal metabolic, psychological, and immune outcomes. This study analyzes the scientific production on MED during pregnancy.

MATERIALS AND METHODS:

descriptive bibliometric study was conducted on original articles addressing MED in pregnant women, published in Scopus (2015-2024). Predefined inclusion and exclusion criteria were applied, selecting 211 documents. We used SciVal and Bibliometrix (RStudio) to estimate production, bibliometric impact, and collaboration network indicators; Bradford’s law to identify core journals; and MS Excel for trend analysis.

RESULTS:

Scientific output has shown sustained growth over the last decade, concentrated in Q1 journals such as Nutrients, American Journal of Clinical Nutrition, and Frontiers in Nutrition. Spain led in volume and impact, with consolidated networks involving institutions such as Harvard University. National co-authorship showed higher average impact than international collaborations. Latin America, Africa, and much of Asia were underrepresented, limiting the global applicability of findings.

CONCLUSION:

Research on the Mediterranean diet during pregnancy has shown consolidation in both volume and impact, driven by scientific advances and the inclusion of this dietary pattern in clinical guidelines. However, geographic, and thematic gaps remain, requiring more inclusive, multicenter, and population-diverse research agendas to maximize global relevance and applicability.

Introduction

Pregnancy is a critical stage in a woman’s life, during which nutrition plays a fundamental role in ensuring both maternal well-being and proper fetal development. Pregnant women require a specific dietary intake that optimizes fetal development and supports the mother’s health.[1] A healthy and nutritious diet during this stage contributes significantly to optimal fetal growth and increases the potential for long-term health for both.[2]

In this context, the Mediterranean diet has been widely recognized for its benefits to overall health and, more recently, for its positive impact during pregnancy. This type of diet is based on high consumption of minimally processed foods, such as fruits, vegetables, whole grains, legumes, nuts, olive oil, fish, and seafood, with moderate intake of dairy products and meat, especially avoiding red and processed meat.[3] This dietary pattern has been shown to reduce the risk of multiple adverse outcomes during pregnancy, such as gestational diabetes, intrauterine growth restriction, preterm births, and low birth weight.[3,4]

Several recent studies have explored the relationship between adherence to the Mediterranean diet and maternal and child health. Evidence indicates that adherence to this diet not only improves the mother’s metabolic and psychological health but is also associated with improved breast milk composition and reduced stress and anxiety levels during pregnancy.[4,5] In addition, it has been observed that interventions based on the Mediterranean diet can positively influence placental size and fetal growth.[6] In relation to these findings, it has been proposed that the benefits of the Mediterranean diet could be mediated by changes in the gut microbiota.[7] Furthermore, it has been shown that a diverse Mediterranean diet during pregnancy can reduce the risk of developing allergic diseases in early childhood, reinforcing the modulatory role of dietary patterns on the developing immune system.[8] Finally, new research suggests that the impact of the Mediterranean diet goes beyond physical aspects, also influencing the mother’s brain morphology during pregnancy.[5]

Maternal health care requires the integration of up-to-date evidence to guide clinical practice and public health interventions. For health professionals, understanding the magnitude and strength of the evidence on the Mediterranean diet during pregnancy is essential when designing strategies for nutritional counseling, prevention of obstetric complications, and promotion of healthy eating habits in pregnant women. However, the rapid expansion of scientific literature makes it difficult to clearly identify research trends, key players, and knowledge gaps in this area. In this context, a bibliometric study emerges as a methodological tool that allows for mapping and synthesizing existing scientific production, highlighting the main lines of research, collaboration between institutions and countries, and the impact of the knowledge generated. This analysis not only facilitates informed decision-making in the field of maternal health care but also helps guide future research toward areas of greater clinical and social relevance.

Therefore, the objective of this study is to analyze the trend, collaboration, and impact of scientific output on the Mediterranean diet in pregnancy.

Materials and Methods

Study design and database

Descriptive observational study conducted using a bibliometric approach, considering articles on the Mediterranean diet during pregnancy published and indexed in Scopus.

Search strategy

To create the search equation, MeSH terms related to the topic were searched for and connected using Boolean operators. The search was limited to the abstract and title fields, resulting in the following final search strategy: TITLE-ABS ((“Diet Mediterranean” OR “Mediterranean Diet” OR “Diets Mediterranean” OR “Mediterranean Diets”) AND (“Pregnancy” OR “Pregnancies” OR “Gestation” OR “Pregnant Woman” OR “Woman Pregnant” OR “Women Pregnant” OR “Women Pregnant” OR “Pregnant Women” OR “Third Trimester Pregnancies” OR “Third Trimester Pregnancy” OR “Second Trimester Pregnancies” OR “Second Trimester Pregnancy” OR “First Trimester Pregnancies” OR “First Trimester Pregnancy”)) AND PUBYEAR > 2014 AND PUBYEAR < 2025. The search was performed on September 17, 2025, finding 293 published documents.

Eligibility criteria

The following eligibility criteria were established for the selection of publications:

Inclusion criteria

• Original articles.

• Articles published between 2015 and 2024.

• Articles that studied the Mediterranean diet.

• Articles conducted in populations of pregnant women.

Exclusion criteria

• Articles indexed in databases other than Scopus.

• Review articles.

• Other types of documents (books or book chapters, notes, errata, or short surveys).

Applying the established criteria, 211 original articles on the Mediterranean diet during pregnancy were selected for inclusion. It should be noted that there were no language restrictions in the selection process.

Data analysis

The following bibliometric indicators were estimated using the Scival tool: scholarly output, citations, citations per publication, field-weighted citation impact, and h-index. The metadata of the selected publications were exported in CSV format, and this file was imported into the Bibliometrix package of the RStudio program, version 2024.12.1, which was used to create a map of the international collaboration network and a graph of the main scientific journals according to Bradford’s Law. The trend line was created using MS Excel 2019.

Ethical consideration

Given the type of study, which did not involve the participation of human subjects or personal data, approval from a research ethics committee was not required to carry it out.

Results

The international collaboration map shows the United States as the country with the most extensive collaboration network, with countries in Europe, Asia, and Oceania. Spain is the leading European country and has ties with Chile. The South American region shows little research participation in this thematic field. These patterns suggest that scientific production is structured in consolidated networks and that certain countries play a bridging role in global collaboration [Figure 1].

Figure 1.

International collaboration network

Articles with a single author are less common (1.3%), while those with national collaboration were the most frequent (53.1%); in addition, this type of publication has a better impact (19.2 citations per publication) and 43% more expected citations than the global average. This could be explained by the existence of established research groups within institutions, access to shared resources, stable academic networks, and national funding. International collaboration accounted for 30.8% and had the second highest impact [Table 1].

Table 1.

Type of collaboration in scientific production on the Mediterranean diet during pregnancy

Metric		Scholarly output				Citations		Citations per publication		Field-weighted citation impact
		n		%
International collaboration		65		30.8%		1105		17		1.22
Only national collaboration		112		53.1%		2151		19.2		1.43
Only institutional collaboration		30		14.2%		351		11.7		1.16
Single authorship (no collaboration)		4		1.9%		15		3.8		0.25

Among the institutions with the highest scientific output, most are from Spain. The Carlos III Health Institute and the Biomedical Research Networking Center led this scientific field, although the University of Barcelona has a better weighted citation impact (2.16) and the Hospital Clínico San Carlos in Madrid has a better average number of citations per publication (30.1). Harvard University is the only institution in the United States ranked among the most productive, and it is also one of the most impactful [Table 2].

Table 2.

Top 10 institutions with the highest scientific output on the Mediterranean diet during pregnancy

Institution		Country		Scholarly output		Citations		Citations per publication		Field-weighted citation impact
Instituto de Salud Carlos III		Spain		50		1195		23.9		1.55
Centro de Investigación Biomédica en Red		Spain		50		1195		23.9		1.55
University of Granada		Spain		18		274		15.2		1.11
Complutense University		Spain		16		475		29.7		1.3
University of Barcelona		Spain		16		402		25.1		2.16
Harvard University		United States		16		470		29.4		2.3
Hospital Clínico San Carlos de Madrid		Spain		15		452		30.1		1.37
August Pi i Sunyer Biomedical Research Institute		Spain		11		176		16		2.08
SJD Barcelona Children’s Hospital		Spain		11		176		16		2.08
Hospital del Mar		Spain		8		174		21.8		1.98

The most productive authors are from Spain. Rubio Miguel Ángel, Calle-Pascual Alfonso Luis, and Barabash Ana lead this research area; however, de la Torre Nuria Garćia has a higher average number of citations per publication (38.7), and Casas, Rosa M has 108% more citations than the world average [Table 3].

Table 3.

Top 10 authors with the highest scientific output on the Mediterranean diet during pregnancy

Name		Affiliation		Scholarly output		Citations per publication		Field-weighted citation impact		h-index
Rubio, Miguel Ángel		Hospital Clínico San Carlos, Madrid, Spain		14		31.3		1.4		39
Calle-Pascual, Alfonso Luis		Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición, Spain		14		31.3		1.4		33
Barabash, Ana		Universidad Complutense de Madrid, Facultad de Medicina, Spain		14		31.3		1.4		27
del Valle, Laura		Hospital Clínico San Carlos, Spain		13		33.7		1.51		16
Valerio, Johanna Josefina		Hospital Clínico San Carlos, Madrid, Spain		13		20.9		1.3		8
Durán, Alejandra I.		Hospital Clínico San Carlos, Madrid, Spain		13		33.7		1.51		20
Familiar-Casado, Cristina		Hospital Clínico San Carlos, Madrid, Spain		12		30.8		1.33		10
de la Torre, Nuria Garćia		Hospital Clínico San Carlos, Madrid, Spain		11		38.7		1.52		19
Casas, Rosa M.		Centro de Investigación Biomédica en Red-Fisiopatología de la Obesidad y Nutrición, Spain		11		16		2.08		41
Torrejón, María José		Hospital Clínico San Carlos, Madrid, Spain		11		36.8		1.6		16

Scientific journals in the Q1 quartile have the most published articles; among these, the journal Nutrients is the most relevant in the field, with 44 articles, followed by the American Journal of Clinical Nutrition and Frontiers in Nutrition, both with 7 articles. The journal Nutrición Hospitalaria, published by a Spanish publisher and ranked in the Q3 quartile, is also among the most important [Figure 2].

Figure 2.

Core Source by Bradford’s Law describes the dispersion of scientific output in each field. Journals are grouped into three zones: zone 1, consisting of journals that account for the largest proportion of articles; zone 2, consisting of an intermediate group of journals with moderate output; and zone 3, consisting of numerous journals with few articles each

Journals in the Q1 quartile show a steady upward trend with a higher number of publications compared to journals in the other quartiles. Those in the Q2 quartile show slight growth over the years, although there was a decline from 2022 to 2024. Those in the Q3 and Q4 quartiles are consistent in their trend, with fewer publications [Figure 3].

Figure 3.

Trend in scientific output on the Mediterranean diet during pregnancy. The temporal evolution of the number of publications distributed according to the journal quartile (Q1-Q4) is shown. The quartiles reflect the relative position. The quartiles reflect the position of the journals in terms of impact and prestige in their subject category. The concentration of production in higher quartile journals (Q1 and Q2) indicates greater visibility and quality of the research published in the area

Discussion

This bibliometric study provides a comprehensive and up-to-date overview of the evolution of scientific output related to the Mediterranean diet during pregnancy, showing sustained growth over the last decade. The concentration of publications in Q1 quartile journals, especially Nutrients, American Journal of Clinical Nutrition, and Frontiers in Nutrition, suggests an editorial consolidation that favors the dissemination of research in this field, which has also been observed in other bibliometric analyses focused on reproductive health, metabolic diseases, and cancer.[9,10]

This increase coincides with relevant milestones, such as the incorporation of the Mediterranean diet into international clinical guidelines for the prevention of chronic diseases, as well as a renewed interest in the relationship between diet, microbiota, and immunity in the context of the COVID-19 pandemic.[11,12] These factors seem to have promoted new research agendas around preventive dietary patterns during critical stages such as pregnancy, in line with what Sheng et al.[13] and Zhang et al.[14] report on fetal metabolic programming and its nutritional determinants.

The collaboration analysis reveals that nationally co-authored articles predominate in both frequency and impact, surpassing even internationally co-authored works in citations per publication. This finding, also reported in other studies,[15] this may be because this type of collaboration tends to focus on common research agendas and issues specific to the local context, which can generate greater immediate interest in the scientific community in the area, resulting in a higher number of citations. In addition, geographical and institutional proximity facilitates coordination between teams, access to national funding, and the consolidation of stable networks. However, international collaboration continues to play an important role, especially in facilitating knowledge transfer between countries with different scientific production capacities.

Spain consistently stands out as the main research hub, with institutions such as the Carlos III Health Institute, CIBER, and the University of Barcelona leading in both volume and weighted impact. Harvard University’s position as the only US institution among the most productive reinforces the idea that nodes of excellence tend to be concentrated in established transnational networks.[16,17] In terms of authorship, the leadership of Spanish researchers such as Rubio MA and Barabash A. is confirmed, although figures such as Rosa M. Casas and Nuria García de la Torre stand out for their relative impact significantly above the global average, possibly associated with their participation in emerging studies on microbiota, inflammation, and fetal metabolism.[12,13]

One aspect that deserves special attention is the marked underrepresentation of Latin America, Africa, and regions of Asia in scientific production on this topic. This could be linked to limited funding opportunities, insufficient scientific and technological infrastructure, and the heavy teaching and administrative workload of researchers in low- and middle-income countries. Added to this is publication bias, which tends to favor studies conducted by established institutions in high-income countries, and the lower participation of regional journals in international databases. South America barely appears, with scattered links, mainly to Spanish institutions, which coincides with previous findings on structural inequalities in science and technology.[15,18] This geographical asymmetry has direct implications for the applicability of the findings, given that most studies are conducted in European or high-income populations, leaving aside contexts with different sociocultural, dietary, and epidemiological realities.[19] This lack of diversity is also reflected in the limited inclusion of non-European ethnic groups, which limits the generalizability of the results.

In this regard, future research needs to adopt more inclusive, multicenter approaches with greater population diversity. It is a priority to expand the analysis to regions with a high burden of gestational disease and limited coverage in maternal nutrition. In addition, underdeveloped lines of research should be explored, such as sustained adherence to the Mediterranean diet during pregnancy, its relationship with long-term maternal-fetal outcomes, and its potential in the primary prevention of chronic diseases in offspring.[14,20] The use of precision medicine tools, such as metabolomics and microbiota analysis, could enrich this agenda.

From a science policy perspective, the findings of this study can guide strategic decisions regarding the allocation of resources for maternal health research, the prioritization of emerging nutritional issues, and the strengthening of regional scientific networks. The consolidation of journals such as Nutrients as a dominant publication platform also raises questions about the need to open new multilingual and open-access publishing spaces that allow for greater inclusion of countries with low scientific visibility.

From a clinical perspective, the results of this study reinforce the importance of incorporating the Mediterranean diet as a pillar of nutritional recommendations during pregnancy. Growing evidence of its significant benefits suggests that this dietary pattern can become an effective strategy for reducing manageable risks such as diabetes, hypertension, and adverse perinatal outcomes. It can also enable healthcare professionals to identify more consolidated and up-to-date sources of evidence, which contributes to strengthening prenatal care guidelines, optimizing nutritional counseling, and promoting the implementation of evidence-based dietary interventions at different levels of the healthcare system.

This bibliometric research has limitations inherent to its design. The exclusive use of the Scopus database may have left out publications indexed on other platforms; however, it is recognized that Scopus adequately characterizes the scientific literature in health sciences [21]. In addition, errors or missing metadata are possible due to the indexing process, and self-citations were not excluded, which may have affected some bibliometric indicators. Finally, this type of analysis focuses on production and impact metrics, without evaluating the methodological quality or clinical validity of the included studies, which should be considered when interpreting the results. The exclusion of gray literature and clinical guideline documents should also be considered, as well as the possibility of citation inflation by collaborative networks.

Conclusion

In conclusion, research on the Mediterranean diet during pregnancy shows clear consolidation in terms of volume, impact, and institutional networks, driven by recent scientific developments and global transformations in public health. However, critical gaps remain, both geographical and thematic, which need to be addressed with a more inclusive, contextualized, and user-oriented research agenda. Advancing in this direction will require not only new methodological designs, but also a political and scientific commitment to democratize access to knowledge and ensure that the benefits of this dietary pattern reach all pregnant women, regardless of their geographical origin or socioeconomic status.

AI policy statement

No generative AI tools were used in the preparation of this study.

Ethical approval

Since this study does not involve human subjects—rather, it involved only the review of publicly available data—approval by a research ethics committee was not required.

Author’s contributions

JBO and ALB: Concept, JBO and BGC: Design, ZZG, ESS and MSR: definition of intellectual content BCG and ALB: literature search, JBO: data acquisition, JBO and BGC: data analysis, JBO: statistical analysis, JBO, ALB, BGC, ZG, ESS and MSR: manuscript preparation, JBO, ALB, BGC, ZG, ESS and MSR: manuscript editing, JBO, ALB, BGC, ZG, ESS and MSR: manuscript review.

Data availability statement

The datasets generated during the current study are not publicly available but are available from the corresponding author upon reasonable request.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.