Globally, complementary and alternative medicine (CAM) has become an integral part of healthcare practices for several decades, influenced by cultural traditions, historical values, and the growing demand for holistic approaches to healthcare (Hasan et al., 2009; Islahudin et al., 2017; James et al., 2018b). Recognizing the significance of CAM in promoting patient autonomy and patient-centered care, Brazil officially integrated CAM into its Unified Health System (SUS) through a national ordinance in 2006 (Series, 2008; Boccolini et al., 2022). According to the National Health Survey (PNS), approximately 5% of Brazilian adults use CAM, with a greater prevalence among women (Boccolini et al., 2022). Furthermore, 13%–30% of pregnant women in Brazil reported using medicinal herbs, indicating a significantly higher prevalence compared to the general population (Araújo et al., 2016; da Matta et al., 2021).

Interest in the use of herbal medicine (HM) among pregnant women persists (Abdollahi and Chareti, 2019; El Hajj and Holst, 2020; Jahan et al., 2022), as pregnant women seek ways to manage various health conditions during pregnancy while avoiding potential risks associated with synthetic medications (Nyeko et al., 2016; Ahmed et al., 2018; James et al., 2018a). However, despite their belief in HM as a safer alternative to conventional drugs, concerns have been raised regarding the safety and effectiveness of HM use during pregnancy (Marcus and Snodgrass, 2005; Kennedy et al., 2016; Ahmed et al., 2017; El Hajj and Holst, 2020). The use of HM is predominantly supported by anecdotal evidence, and many herbs lack scientific research to determine their safety during pregnancy (Frawley et al., 2014; Smeriglio et al., 2014). Moreover, even for the herbs that have been studied extensively, conflicting clinical recommendations exist due to varying opinions on consumption limits (Ahmed et al., 2017; Sarecka-Hujar and Szulc-Musioł, 2022). As a result, the discrepancies in available evidence and its application in healthcare pose health risks to pregnant women and the developing fetus, highlighting the need to address the knowledge gaps and promote evidence-based guidelines.

Similar concerns have emerged in Brazil, where certain herbs commonly used by Brazilian women have been identified as potentially harmful during pregnancy (Moreira et al., 2014; Araújo et al., 2016). For example, Brazilian women frequently consume Peumus boldus Mol., Foeniculum vulgare Mill., and Cymbopogon citratus Stapf., despite the teratogenic and abortifacient properties of these herbs (Araújo et al., 2016; Casagrande et al., 2023; Souza et al., 2023). Many women persist in using these contraindicated herbs, inadvertently endangering themselves and their babies due to simple ignorance (da Matta et al., 2021). Furthermore, previous safety evaluations of Brazilian herbs are primarily based on Resolution SES/RJ No. 1757, which was published in 2002 (Saúde, 2002; Araújo et al., 2016; da Matta et al., 2021). Considering the growing popularity of HM use among pregnant women in Brazil, it is crucial to investigate the use of HM in different regions of Brazil and assess the safety of commonly used herbs based on current scientific evidence. Therefore, this study aims to explore the use of HM among pregnant women in São Paulo, the most populous city in Brazil, and evaluate the safety profile of the identified herbs.

This cross-sectional study investigated the use of HM among pregnant women in São Paulo, Brazil, and our findings revealed that approximately 20% of Brazilian women used HM during pregnancy. The observed prevalence was lower than the findings reported in a previous study conducted in the northeastern part of Brazil, and this discrepancy can be attributed to variations in sample sizes of the studies and cultural diversity in the studied regions (Araújo et al., 2016). However, when comparing the prevalence with that of Brazilian adults, as reported in the National Health Survey, pregnant women demonstrated a higher prevalence of complementary medicine use (de Moraes Mello Boccolini and Siqueira Boccolini, 2020; Boccolini et al., 2022). This suggests that pregnant women are more likely to explore natural treatment options for alleviating physical discomforts, as the women are trying to protect their developing fetus from any teratogenic and fetotoxic effects of conventional medications (John and Shantakumari, 2015; Illamola et al., 2020). Similarly, a significant number of women in our study reported using HM during pregnancy based on their perceived effectiveness and safety (Borrelli et al., 2007). These findings provide insights into the beliefs and perceptions of Brazilian pregnant women regarding HM as a safe and viable treatment option.

In line with previous findings, minor ethnicity and previous experience of HM use were found as potential predictors of HM use during pregnancy (Kalder et al., 2011; Hall and Jolly, 2014; Pallivalappila et al., 2014; El Hajj et al., 2020). Many minor ethnic groups have a longstanding history of traditional medicine use, and the use of HM is often rooted in traditional health practices (Ray et al., 2018; Agu et al., 2019). Consequently, individuals who belong to minor ethnic groups and have a cultural background in the use of HM may have a greater tendency to use such remedies. Furthermore, having prior experience of HM use and being familiar with HM could influence the women to be more comfortable using HM; therefore, women who have previously used HM are more likely to continue its use during pregnancy (Pallivalappila et al., 2014; El Hajj et al., 2020; Ahmed et al., 2022).

Our study identified the use of 20 different types of HM during pregnancy, and 40% of these herbs were found to be contraindicated or recommended with caution. Among the herbs that should be used with caution, the prevalence of C. aurantifolia intake was most prevalent. C. aurantifolia is commonly used as both a food product and a phytomedicine, due to its diverse range of beneficial properties, such as antibacterial, anticancer, and anti-inflammatory effects (Narang and Jiraungkoorskul, 2016; Lee et al., 2018; Shafreen et al., 2018; Indriyani et al., 2023). Also, it is a popular home remedy among pregnant women for the treatment of morning sickness and urinary tract infections (Rahmawati, 2018; Ramadhani et al., 2020). However, an animal study found an abortifacient effect of lime juice, raising concerns about its safety during pregnancy (Bakare et al., 2012). Furthermore, excessive consumption of citrus fruits can lead to heartburn and indigestion, posing additional risks (Nundy, 2016; Hoffmann, 2017). Furthermore, using its essential oil at high concentration may result in necrosis and trigger an inflammatory response (Brah et al., 2023). Previous reviews have also advised against the use of C. aurantifolia due to the lack of sufficient clinical evidence regarding its safety (Kennedy et al., 2016; Ramadhani et al., 2020). Therefore, despite its widespread use and perceived safety, the current scientific evidence suggests that the therapeutic use of C. aurantifolia during pregnancy should be approached with caution.

Moreover, even herbs that are considered safe can have adverse effects if it is consumed in amounts more than typically found in food. For example, M. recutita is commonly used among pregnant women for flu, gastrointestinal irritation, and anxiety management (Ahmed et al., 2017; Bebitoglu, 2020; El Mihyaoui et al., 2022). Despite being considered safe for pregnancy (Kennedy et al., 2016; Ahmed et al., 2017; Al-Snafi and Hasham, 2023), prolonged administration of M. recutita was associated with a greater risk of preterm labor or miscarriage (Cuzzolin et al., 2010; Ahmed et al., 2017; Balbontín et al., 2019; Bebitoglu, 2020). Moreover, the Brazilian Resolution - SES/RJ No. 1757 categorizes M. recutita as contraindicated due to its emmenagogue properties (Saúde, 2002; Araújo et al., 2016). Similarly, A. sativum, another widely used HM among pregnant women in Brazil, has been identified as safe during pregnancy with no major adverse effects (Kennedy et al., 2016; Ahmed et al., 2017; Sarecka-Hujar and Szulc-Musioł, 2022; Sahidur et al., 2023). Nevertheless, consuming excessive amounts of A. sativum can result in gastrointestinal discomfort, and when used concomitantly with anticoagulants or antiretroviral drugs, it may cause drug-drug interactions (Borrelli et al., 2007; Kaur et al., 2013; Okoro et al., 2023). Considering that many herbs still lack comprehensive scientific investigations to definitively establish their safety, further clinical research is necessary to evaluate their potential toxicity during pregnancy. Moreover, maintaining active pharmacovigilance reporting is crucial to systematically record any adverse events that may arise.

In addition to the concerns regarding the lack of sufficient clinical evidence supporting the safety of HM, there are concerns related to the quality control of herbal products available in the market (Zhang et al., 2012; Okem et al., 2014). Even though some HM possess potent pharmacological properties, they are often classified as food or food additives and are not strictly regulated as pharmaceutical products (Heinrich, 2015). Consequently, there are potential risks associated with the quality of herbal products in the market, such as heavy metal contamination, inadequate supply chain management, and difficulties in controlling the potency of HM (Fong, 2002; Zhang et al., 2012; Okem et al., 2014; Luo et al., 2020). Consumption of contaminated or adulterated HM can have detrimental effects on health (Ezeabara et al., 2014). Therefore, it is crucial for pregnant women to exercise caution when using HM and consult their obstetric care providers before use.

Nevertheless, consistent with previous research, a significant number of pregnant women in our study obtained information about HM from family and friends, rather than healthcare professionals (Araújo et al., 2016; Ahmed et al., 2020; Eid and Jaradat, 2020; Ahmed et al., 2022). In addition, almost half of the women chose not to disclose their HM use to the obstetric care providers, either due to a lack of inquiry from the healthcare providers or for no specific reason. Such reliance on informal sources of information and the hesitancy to disclose HM use highlight the need for improved communication between pregnant women and obstetric care providers regarding HM. Furthermore, considering most women were willing to discuss HM use if the doctors initiated the conversation, obstetric care providers should play a proactive role in providing appropriate guidance and feedback regarding the use of HM during antenatal care consultations. Through these efforts, healthcare providers can effectively contribute to preventing potential health risks associated with the inappropriate use of HM during pregnancy by helping pregnant women make informed decisions and safer healthcare choices (Ahmed et al., 2020).

The current study has several limitations that should be considered when interpreting the results. Firstly, the generalizability of the study findings may be limited as the survey was conducted retrospectively at a single hospital in São Paulo. However, the data was collected from one of the public teaching hospitals that handle a substantial number of deliveries annually (>4,000 deliveries). In addition, to minimize the potential recall bias of the survey data, information was collected from postpartum women admitted to the maternal wards before discharge and those who had given birth within the last 6 weeks. Furthermore, due to the low frequency of delivery complications and congenital anomalies within our sample of 333 participants, we were unable to establish a significant association between HM use and pregnancy outcomes. This warrants further study with a more extensive and diverse sample size to draw more conclusive findings. Lastly, due to the cross-sectional study design, we could only establish associations between the variables and could not determine causality. Despite these limitations, our study provides valuable insights into HM use among pregnant women in Brazil based on current available evidence. In addition, our findings highlight the importance of developing reliable and evidence-based clinical guidelines to manage inappropriate HM use during pregnancy.

This study revealed that driven by misconceptions about the safety and effectiveness of HM, pregnant women in Brazil unknowingly jeopardize their own health and that of the newborns by using herbs that are contraindicated or potentially harmful during pregnancy. Updating antenatal care guidelines based on the latest scientific evidence and fostering transparent communication on HM use during consultations can help obstetric care providers make better clinical decisions and effectively monitor the health of both pregnant women and their babies. Lastly, sustained efforts must be taken to generate scientific evidence concerning the safety and clinical efficacy of commonly used HM, providing the foundation for informed medical practices and ultimately contributing to improved maternal and neonatal outcomes.