Peripartum respiratory complications constitute a complex set of multifactorial diseases, most commonly occurring during intrapartum and postpartum (1). They represent a significant factor for pregnant women requiring ICU admission and are a common cause of maternal mortality (2). Adaptive changes in the respiratory and circulatory systems during pregnancy render women susceptible to a range of respiratory complications, including asthma, pulmonary infections, pulmonary edema, pulmonary embolism, acute respiratory distress syndrome, with a more severe course compared to non-pregnant individuals (3). The hypercoagulable state in pregnancy increases the risk of venous thromboembolism fourfold, with subsequent pulmonary embolism remaining a major cause of morbidity and mortality in pregnant women in developed countries (4). Over the past two decades, there has been an increased incidence of severe perinatal pulmonary complications, notably represented by acute respiratory distress syndrome, with an overall incidence ranging from 15.9 to 130 cases per 100,000 deliveries (5). The viral pandemic of COVID-19 in 2019 has further exacerbated this trend. Scholars are increasingly focusing on the field of perinatal respiratory system complications, yet there remain numerous questions requiring further exploration in this area.

Bibliometrics employs quantitative and statistical methods to analyze existing scientific literature, facilitating comparisons of contributions from different countries, institutions, authors, and journals (6, 7). It is widely used to describe the current state and predict future trends in various medical fields. However, there is currently a lack of research in the field of respiratory system complications during pregnancy. Therefore, the aim of this study is to explore the research focus and frontiers in this area through bibliometric analysis, with the expectation of contributing to the formulation of future guidelines. Besides, we hope to investigate which underlying conditions may increase the risk of pregnant women developing respiratory complications, in order to enable early prevention and management in clinical practice. Furthermore, we hope to identify updated and safer effective treatment approaches for managing severe respiratory complications, thereby improving the overall safety of the pregnancy continuum from the antenatal to the postpartum period.

We employed CiteSpace for bibliometric and visual analysis of articles related to respiratory complications during pregnancy. From 2004 to 2023, research in this field has expanded significantly, leading to an overall upward trend in annual publication volume. Notably, there was a surge in articles from 2019 to 2022, likely influenced by the major outbreak of the novel coronavirus in 2019.

Meanwhile, a simple disciplinary analysis reveals a diverse range of disciplines involved in researching this field. The predominant categories include Cardiac Cardiovascular Systems, Obstetrics and Gynecology, Medicine General Internal and Respiratory System. We also identified influential countries, research institutions, and key authors in the field and their collaboration network. Among the top 10 productive institutions, nine were from the USA and one was from China. The prolific institutions were Harvard University, Baylor College of Medicine, and Johns Hopkins University. The USA exhibited the highest publication volume and signifying its leadership role in this field and its essential position as a hub for collaboration with other countries.

Friedman Alexander M, affiliated with the Department of Obstetrics and Gynecology at Columbia University Vagelos College of Physicians and Surgeons, stands out as the preeminent contributor in this domain. A recent study (32) revealed that the discontinuity in postpartum care was associated with an increased risk of severe conditions, such as heart failure, thromboembolism, and upper respiratory tract infections, along with elevated costs and an extended duration of hospitalization. Several other studies demonstrated that pregnant women contracting influenza during childbirth hospitalization were at a higher risk of severe complications, such as mechanical ventilation and acute respiratory distress syndrome (34). Additionally, women with grand multiple pregnancies faced an increased risk of complications, including disseminated intravascular coagulation, pulmonary edema, and acute heart failure (35). Furthermore, asthma ranked among the most common complications during pregnancy and was associated with a series of moderate risks (including severe maternal morbidity, preeclampsia, gestational hypertension, postpartum hemorrhage, gestational diabetes, maternal mortality, and venous thromboembolism). However, no increased risk was found for severe respiratory system complications (mechanical ventilation, temporary tracheostomy, adult respiratory distress syndrome, and status asthmaticus) among deliveries with asthma (36).

As for the keyword clustering analysis, we classified the total keywords into 17 clusters. “Cardiovascular diseases” stands out as the predominant cluster. Peripartum cardiomyopathy and preeclampsia may lead to the development of complications such as disseminated intravascular coagulation syndrome, pulmonary edema, postpartum cerebrovascular diseases, and acute respiratory distress syndrome (37, 38). The occurrence of arrhythmias during pregnancy presenting a potential or direct risk factor for cardiovascular-related mortality in expectant mothers, which may increase the potential risk of pulmonary embolism. Pregnant women with pre-existing pulmonary arterial hypertension may suffer additional cardiac burden (39), which could trigger a series of respiratory complications, including shortness of breath, hypoxemia, and, in severe cases, respiratory failure (40, 41). “COVID-19” exhibits strong infectivity and can trigger a cytokine storm, leading to pneumonia, severe lung injury and acute respiratory distress syndrome (ARDS)-like lung damage, posing a high mortality risk in pregnant women. Due to the physiological changes during pregnancy, the symptoms of women who have pre-existing lung or cardiovascular diseases may worsen after pregnancy. Therefore, preconception counseling for such pregnant women is crucial, and the management of their respiratory tract should also be emphasized.

“Venous thromboembolism,” particularly “pulmonary embolisms” a critical challenge in maternal health. Factors related to pregnancy (cesarean section, preeclampsia, multiple pregnancies, gestational diabetes) and non-pregnancy-related factors (advanced maternal age, ethnicity, obesity, recent surgery, smoking, thrombophilia, in vitro fertilization) can increase the risk of venous thromboembolism (42). Autoimmune disorders like antiphospholipid syndrome, as well as Systemic lupus erythematosus (SLE) warrants attention. In addition to the increased risk of thrombotic events, antiphospholipid antibody syndrome can also directly lead to pulmonary manifestations, including pulmonary hypertension (as defined by echocardiography or cardiac catheterization), pleuritis, pulmonary hemorrhage, pneumonia, and pulmonary fibrosis. Recent studies have suggested that vitamin D may play a role in improving thrombotic events related to antiphospholipid antibody syndrome (43). Lupus myocarditis, the cardiac system complication of systemic lupus erythematosus, which presents as left ventricular dysfunction, acute heart failure, and pulmonary edema, is a rare but life-threatening complication that needs to be differentiated from pneumonia (44). Most pregnant patients with HHT may develop congenital pulmonary arteriovenous malformations, which can lead to low oxygen tolerance and increased risks of respiratory tract infections and thromboembolism, even life-threatening complications such as bleeding, massive hemoptysis, and hemothorax, requiring urgent surgical treatment.

Also, “cesarean section” was linked with venous thromboembolism (26). Furthermore, the choice of anesthesia methods and intraoperative airway management during cesarean sections may give rise to respiratory complications (30, 31). The top 25 keywords with citation bursts over the past 5 years were listed in our result, and “COVID-19” was the strongest burst appeared in 2020. As a result, scholars had shown extensive interest in understanding the pathogenic mechanisms of this disease and in managing pregnant women affected by it, with the goal of improving maternal survival rates. Therefore, the outbreak of the COVID-19 pandemic may be an important turning point, which shifted research focus away from areas like pulmonary hypertension, preeclampsia and arrhythmias, toward the infectious consequences of COVID-19, such as cytokine storm and hypercoagulability in pregnant women. Additionally, the treatment methods represented by ECMO may also be potential research hotspots in the near future.

The relationship in which two or more papers are simultaneously cited by one or more later papers is referred to as a co-citation relationship (45). CiteSpace facilitates the analysis of co-citation within scholarly literature. The amalgamation of co-cited documents shapes the foundational knowledge within a given domain, while the assemblage of citing documents that reference this knowledge base defines the cutting edge of research. The nomenclature assigned to clusters in CiteSpace is derived from the extraction of noun phrases found within the citing documents, thereby signifying the forefront of research in the respective field (8). In our investigation, we found 10 major clusters label included COVID-19 pandemic, congenital heart disease, severe acute respiratory syndrome coronavirus, venous thromboembolism, hypoxemic respiratory failure, obstetric management, atrial fibrillation, pregnancy management, postoperative pulmonary complication, life-threatening condition.

Study the landmark references, six out of the top 10 cited articles were related to coronavirus. “Clinical manifestations, risk factors, and maternal and perinatal outcomes of coronavirus disease 2019 in pregnancy: living systematic review and meta-analysis (46),” was published in BMJ-British Medical Journal by Allotey John in 2020. This analysis demonstrated that pregnant women and recently pregnant women are less likely to experience symptoms such as fever, respiratory difficulties, cough, and muscle pain compared to non-pregnant individuals with COVID-19. However, there is an increased risk of admission to the intensive care unit and receiving invasive ventilation. Advanced maternal age, high body mass index, non-white ethnicity, pre-existing comorbidities, and pregnancy-specific conditions (such as preeclampsia and gestational diabetes) are associated with severity.

Among the remaining four articles, one study (3) documented instances of H1N1 influenza virus infection in pregnant women during the 2009 outbreak in the United States. This article was published in the Lancet. Compared to non-pregnant patients, pregnant women were more prone to severe respiratory distress syndrome, necessitating urgent mechanical ventilation and exhibiting respiratory distress symptoms.

“2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension” (47). This comprehensive guideline was published in the European Heart Journal in 2016. The guideline systematically elucidates the epidemiology and genetic research progress of pulmonary arterial hypertension, providing the basis for clinical diagnosis, such as clinical manifestations, electrocardiograms, chest X-rays, pulmonary function, arterial blood gas analysis, echocardiography, etc. It comprehensively describes the classification of pulmonary hypertension, including pulmonary arterial hypertension, pulmonary hypertension that due to left heart disease, pulmonary diseases and/or hypoxia, chronic thromboembolic pulmonary hypertension and pulmonary hypertension with unclear and/or multifactorial mechanisms.

To ensure the quality of the articles, data were exclusively retrieved from the WoSCC database, potentially leading to the exclusion of papers not indexed in SCI. Continuous updates to the database emphasize the need for ongoing validation by future scholars in our field of analysis. Additionally, due to inherent limitations in CiteSpace software, the study focused solely on English literature, potentially overlooking relevant non-English specialized literature. Despite efforts to broaden the search strategy with extensive free terms, some articles pertinent to the research topic may not have been included. In summary, these limitations may introduce constraints to the comprehensiveness of our research results. However, the identified research trends in this paper are not expected to be significantly biased as a result of these constraints.

Besides, due to the COVID-19 outbreak from 2019 to 2022, research in this field has mostly focused on it in the past 3 years, potentially influencing future research priorities in the field. However, respiratory infections in pregnant women are already a significant concern, and lessons from COVID-19 may help us manage upper respiratory tract infections in critically ill pregnant women, reducing severe complications and improving outcomes.

This study undertook a bibliometric analysis of articles related to respiratory complications during pregnancy, specifically focusing on publications in SCI and ESCI journals over the last two decades. We utilized CiteSpace software to identify the primary countries, institutions, authors, and journals in this research field, offering potential collaboration references for interested researchers. Additionally, CiteSpace software was employed to expand the knowledge base in this field and analyze potential research hotspots.

Current research focuses on pregnancy-related venous thromboembolism and pulmonary embolism, as well as a series of preexisting diseases that may cause these clinical conditions. Additionally, there is attention to respiratory complications related to the impact of cardiovascular diseases represented by pulmonary hypertension and atrial fibrillation on the respiratory system, complications during surgeries including cesarean sections, anesthesia management, and postoperative respiratory complications.