Electronic nicotine delivery systems and pregnancy: Recent research on perceptions, cessation, and toxicant delivery

Abstract

Electronic nicotine delivery systems (ENDS), which includes e-cigarettes (ECIGs), are a rapidly-expanding class of products that heat a liquid (which may or may not contain nicotine) to produce an aerosol. The variation of ECIG components is extensive as are their effects on users. Epidemiological data show that while both adults and youth use ECIGs, use among youth has increased dramatically in recent years. Other epidemiological data show that women of reproductive age and some pregnant women are also using ECIGs. The goal of this article is to provide readers with background information about ECIGs, with a focus on recent findings about ECIG use in pregnancy and potential implications. Among pregnant women, correlates of ECIG use include current cigarette smoking, among other factors. Regarding pregnant women’s perceptions of ECIG use in pregnancy, two themes emerge from the literature: many pregnant women perceive ECIGs to be safer than conventional cigarettes, and that ECIGs can aid with smoking cessation. In contrast to these perceptions, there is little concrete evidence that ECIGs help smokers quit. In addition, there are concerns about ECIG nicotine and other toxicant delivery. Nicotine is a toxicant of particular concern for pregnant women, as nicotine is known to harm a developing fetus. There are many limitations to existing research, and the literature is scant in this area. Further, new “pod mod”-style ECIGs such as JUUL present new challenges. Overall, with limited evidence of their effectiveness, and concerns about developmental toxicology, the authors do not recommend that pregnant women use ECIGs.

1 |. WHAT ARE ELECTRONIC NICOTINE DELIVERY SYSTEMS?

Since their introduction to the United States in 2007, electronic nicotine delivery systems (ENDS), have become a rapidly-expanding class of products. The U.S. Food and Drug Administration defines ENDS as “products [that] use an ‘e-liquid’ that may contain nicotine, as well as varying compositions of flavorings, propylene glycol, vegetable glycerin, and other ingredients. The liquid is heated to create an aerosol that the user inhales” (https://www.fda.gov/tobacco-products/products-ingredients-components/vaporizers-e-cigarettes-and-other-electronic-nicotine-delivery-systems-ends). E-cigarettes (ECIGs) can be thought of as a category of ENDS, as ENDS can also include devices that look like cigars or pipes. Throughout this review, we use the term e-cigarettes (ECIGs) to reflect words used in much of the literature cited, although notably, the terms ENDS and e-cigarettes are often used interchangeably.

ECIGs can be classified in various ways, such as whether or not they are closed systems (in which the user cannot manipulate the liquid or other components) or open systems (in which the user can add liquid and sometimes manipulate other components), or by groupings such as “first generation,” “second generation,” and “third generation.” Additionally, numerous terms are used to describe the devices such as “cig-alike,” “pen style,” “tank style,” and “pod mod” (this term refers to the newest products, such as JUUL, which use liquid-containing pods that attach to a device; please note that JUUL is addressed separately toward the end of this article). The variation of ECIG components is extensive and includes: the flavor of the liquid placed in the ECIG (e.g., Zhu et al., 2014); the concentration of nicotine in the liquid (Harvanko, McCubbin, Ashford, & Kelly, 2018; Rudy, Leventhal, Goldenson, & Eissenberg, 2017); the percentage of free-base nicotine versus protonated nicotine (nicotine salts) in the liquid (El-Hellani et al., 2015, 2017); the ratio of liquid solvents such as propylene glycol and vegetable glycerin (Breland et al., 2017); the voltage of the battery and the resistance of the coil, or heater (Breland et al., 2017); the surface area of the coil (Talih et al., 2017); and the type of metal used to make the coil (Olmedo et al., 2018). Fully understanding the effects of each component variation is critical, as they can influence nicotine and toxicant delivery (as described in more detail below).

Several recent reviews and comprehensive reports detail what is currently known about ECIGs as a product class (e.g., Breland et al., 2017; National Academies of Sciences Engineering and Medicine, 2018) as well as ECIG use among youth and young adults (Glantz & Bareham, 2018; USDHHS, 2016). An extensive review of ECIGs is beyond the scope of this article, but readers are directed to previous reviews for more in-depth information about the product class in general. The goal of this article is to provide readers with basic background information about ECIGs, with a focus on recent findings about ECIG use in pregnancy and associated potential implications.

2 |. WHO IS USING ECIGS?

Among adults, 3.5–5.5% say they currently use ECIGs (Coleman et al., 2017; Kasza et al., 2017; Mirbolouk et al., 2018; Phillips et al., 2017). Most adult ECIG users are also cigarette smokers, or “dual users” of both products (e.g., Coleman et al., 2017; Mirbolouk et al., 2018; Patel et al., 2016), and among tobacco users who reported using multiple tobacco products, 22.5% reported using both cigarettes and ECIGs (Kasza et al., 2017). ECIG use differs according to race and socioeconomic status: ECIG use appears to be highest among non-Hispanic Whites (Syamlal, Jamal, King, & Mazurek, 2016), and White or non-Hispanic multi-race individuals (based on percentages only, without any significance testing; Phillips et al., 2017) than other races. Also, the uptake of ECIG use for cessation is more likely among White cigarette smokers (Harlow et al., 2018). In terms of income, research is mixed, with one report indicating the highest use among working adults with an income of less than $35,000 (Syamlal et al., 2016), and another reporting that the uptake of ECIGs for cessation is more likely among higher-income smokers compared to lower-income smokers (Harlow et al., 2018). Among youth, ECIG use has increased dramatically: according to data from the National Youth Tobacco Survey, past 30-day ECIG use among U.S. high school students has increased from 1.5% in 2011 to 11.7% in 2017, exceeding past 30-day cigarette use (7.6% in 2017; Wang et al., 2018). Of particular concern, increasing evidence suggests that ECIG use among youth is a risk factor for cigarette smoking initiation (e.g., Leventhal et al., 2015; Soneji et al., 2017; Watkins, Glantz, & Chaffee, 2018), although the causality of this relationship has not yet been determined.

In terms of sex differences, some surveys show that ECIG use is more prevalent among men than women (e.g., Kasza et al., 2017; Phillips et al., 2017) while others indicate more equal use across sexes (Schoenborn & Gindi, 2015; Weaver et al., 2016). Recent data from the nationally representative Population Assessment of Health and Tobacco survey (PATH, collected in 2013–2014), was analyzed to examine responses among women of reproductive age (15–44 years) and results showed that 5.9% were current ECIG users. Among those who used ECIGs, ECIG use was strongly associated with being a cigarette smoker (Lopez et al., 2018). Dual cigarette and ECIG use has also been observed in other studies of women of reproductive age (Chivers, Hand, Priest, & Higgins, 2016). In addition, a smaller study of female current and former tobacco users aged 18–45 in Kentucky, most of whom were pregnant, revealed that most (65%) had tried e-cigarettes (Ashford et al., 2017).

Little work is in the literature on ECIG use among pregnant, current tobacco smokers and/or ECIG users. One study, using PATH data collected in 2013–2014, showed that 4.9% of the pregnant women in the sample reported current ECIG use, and most were concurrently smoking cigarettes (Kurti et al., 2017). Another survey, using a national sample of pregnant women, showed that 6.5% used ECIGs only and 8.5% used both cigarettes and ECIGs (Wagner, Camerota, & Propper, 2017). Also, in a small survey of pregnant smokers from Connecticut and Massachusetts, 53% reported having ever used an ECIG (Oncken et al., 2017). An analysis of National Health Interview Survey (NHIS) data reported 3.6% (weighted prevalence) of pregnant participants were current e-cig users, with estimates rising to 38.9% among pregnant current cigarette smokers (Liu et al., 2019), Most recently, data from the Pregnancy Risk Assessment Monitoring System from Oklahoma and Texas was published and showed that 7.0% of women reported using an “electronic vapor device” before, during, or after pregnancy (Kapaya et al., 2019). Among women of reproductive age and pregnant women, correlates of ECIG use include younger age, and being White/non-Hispanic (Ashford et al., 2017). Among pregnant women, correlates of ECIG use include smoking more cigarettes per day before becoming pregnant, more frequent attempts to quit smoking, being Hispanic or White/non-Hispanic (Oncken et al., 2017); and concurrent cigarette smoking and past year illicit drug use (Kurti et al., 2017).

3 |. WHAT ARE PREGNANT WOMEN’S PERCEPTIONS ABOUT ECIGS?

As ECIGs have grown in popularity, and use extends into vulnerable populations, a small number of studies have been conducted to assess perceptions of ECIG use among pregnant women. As described in a 2017 literature review of seven peer-reviewed publications from 2013 to 2016 pertaining to perceptions and use of ECIGs in pregnancy, two primary themes emerged: (a) ECIGs as safer than conventional cigarettes, and (b) ECIGs as an aid to smoking cessation (McCubbin, Fallin-Bennett, Barnett, & Ashford, 2017). The few recent publications published since the aforementioned review (from 2017 and 2019 to-date) demonstrate that these primary themes remain, as described in more detail below.

Wagner et al. (2017) conducted a national online survey of pregnant women (N = 445) and found 64.27% of respondents perceived ECIGs to be generally safer than conventional cigarettes, and fewer (35%) believed they were safer than cigarettes in the context of use during pregnancy. Similarly, results from a recent qualitative study of 30 pregnant and postpartum women showed that the majority of participants believed ECIGs to be a less harmful product when compared to cigarettes, although several expressed concerns about ECIG use in terms of safety (Bowker et al., 2018). Finally, results from a cross-sectional survey of 382 pregnant women showed that respondents perceived that ECIGs were associated with lower levels of risk compared to cigarettes (Bhandari et al., 2018).

As pregnancy poses a strong motivation for women to make healthy behavior changes including smoking cessation, the perception of ECIGs as an aid to cessation is an important consideration. Results from recent studies indicate that pregnant women continue to perceive ECIGs as an aid to reducing or quitting cigarette use (Bhandari et al., 2018; Bowker et al., 2018; Kahr et al., 2015; Wagner et al., 2017), despite a report from the U.S. Preventive Services Task Force concluding there is insufficient evidence to support ENDS as a cessation aid (Siu, 2015), and as described in more detail below.

In addition to the two primary themes of ECIGs being safer than cigarettes and ECIGs being smoking cessation aids, researchers have noted additional factors related to ECIG use among pregnant women, including the perceived ability to use ECIGs in otherwise smoke-free areas (England et al., 2016), a lower product cost (Bowker et al., 2018; England et al., 2016), the appeal of various flavors (England et al., 2016; Fallin, Miller, Assef, & Ashford, 2016), especially sweet flavors (Stroud, Papandonatos, Borba, Kehoe, & Scott-Sheldon, 2019), and the lack of awareness of nicotine content in the ECIG liquid (Kahr et al., 2015; Kapaya et al., 2019). Interestingly, women also express a desire for credible information related to ECIG safety, specifically from healthcare providers (Bowker et al., 2018).

4 |. WHAT ARE HEALTHCARE PROVIDER’S PERCEPTIONS ABOUT ECIGS?

A 2014 study in which obstetricians and gynecologists were surveyed reported that only 5% of the participating providers felt informed about ECIG-related health effects, and fewer than 53% of the surveyed providers screened for patients’ exposure to noncombustible tobacco products (England et al., 2014). As ECIG prevalence increases, providers are faced with growing patient inquiries about product safety, despite a lack of research. Further, a qualitative study of 35 physicians from five specialties conducted in early 2016 found that most providers had general knowledge of ECIGs (flavors, that ECIGs contain nicotine, etc.); however, opinions were mixed regarding product safety, although most perceived ECIGs as less harmful than conventional cigarettes (Singh et al., 2017). Among providers, about half perceived ECIGs as an effective aid for smoking cessation (Singh et al., 2017).

In addition, in a study of 115 physicians at Saint Louis University Hospital, provider knowledge and practices regarding ECIGs were assessed, and results indicated that 51% of respondents viewed the products as a tool for harm reduction, while 53% reported patients inquiring about using ECIGs as a smoking cessation aid (Kanchustambham et al., 2017). Somewhat similarly, a survey of 417 family medicine physicians (providing labor and delivery care) in a Texas based study found almost half believed ECIGs users were at a lower risk for cancer compared to conventional cigarette smokers, and 4.4% of providers reported prescribing or recommending ECIGs to pregnant smokers who desired to quit (Northrup et al., 2017). Overall, perceptions of ECIGs among healthcare providers are mixed, and the existing research highlights the need for these professionals to receive accurate, up-to-date information about ECIGs so they can guide their patients appropriately. Some educational materials for patients and/or the general public already exist (i.e., via the American Thoracic Society, the Centers for Disease Control and Prevention [CDC], the American Pregnancy Association, among others). Specific to providers, the American College of Obstetricians and Gynecologists released an updated Committee Opinion on smoking cessation during pregnancy in October 2017 (the most recent update) specifying a “focused change in electronic nicotine delivery systems” (American College of Obstetricians and Gynecologists [ACOG], 2017). The updated Opinion acknowledged the increase in available ECIG products and the perception among some that ECIGs may be safer than conventional cigarette use. However, the Committee emphasized the lack of data regarding the health effects specifically on pregnant women. Most importantly, ACOG reminded providers “nicotine in any form poses considerable health risks and has known adverse health effects on fetal brain and lung tissue (32)” (ACOG, 2017, p. e202).

5 |. CAN ECIGS HELP SMOKERS TO QUIT SMOKING?

The literature on successful ECIG-assisted smoking cessation is mixed, and several studies show that ECIGs do not help smokers quit. For example, a nationally-representative cohort study of current smokers followed for 12 months showed that smokers who used ECIGs were less likely to quit smoking compared to smokers who did not use ECIGs (2015–2016 data; Weaver et al., 2018). Recent survey data from England, using a nationally representative sample, revealed no association between use of ECIGs and cigarettes smoked per day at a population level (Beard, Brown, Michie, & West, 2018). In contrast, some self-report data from survey studies shows that smokers who report using ECIGs daily are more likely to quit smoking for at least 30 days compared to smokers who report nondaily ECIG use (Berry et al., 2018), and others have reported similar findings (e.g., Giovenco & Delnevo, 2018). In addition, in a recent study of PATH data, results showed that daily ECIG users were more likely to quit smoking than never users, although ECIG users were also more likely to relapse to cigarette smoking over time, compared to never users (Verplaetse et al., 2018).

Randomized controlled trials, considered the “gold standard” for answering questions about treatment effectiveness, are the ideal study design with which to determine if ECIGs can help smokers quit, although few have been conducted. One randomized controlled trial showed that after several months of use, about a third of the sample was able to quit smoking (Adriaens, Van Gucht, Declerck, & Baeyens, 2014) although comparisons to a control group are difficult as all participants received an ECIG at some point in the study. A second randomized controlled trial showed cessation rates of 11% at 12 weeks and 9% at 1 year (Caponnetto et al., 2013). A third randomized, controlled clinical trial showed that the ECIG tested was no better than a nicotine patch in terms of cessation (Bullen et al., 2013). In a fourth trial of highly-motivated smokers, more participants randomized to ECIG conditions quit at 3 months (23–25%), compared to participants randomized to a control group (10%; Masiero et al., 2018). Most recently, results from a clinical trial were published, in which cigarette smokers were given nicotine replacement products or an ECIG for 3 months; at the 1-year follow up, 18% of participants in the ECIG condition had quit smoking, compared with 9.9% in the nicotine replacement product group (Hajek et al., 2019). In contrast, other work has shown that in a sample not seeking treatment for smoking cessation, ECIGs may help smokers reduce cigarette use, but few actually quit (Rohsenow, Tidey, Martin, Colby, & Eissenberg, 2018).

Meta-analyses have also been conducted. One meta-analysis of various study types, including RCTs (two of the RCTs included are described above) concluded that available RCTs, when pooled, showed that ECIGs with nicotine were better than ECIGs without nicotine for cessation (although the effect was small; Hartmann-Boyce et al., 2016). Another meta-analysis of a variety of study types concluded that ECIGs may hinder smokers from quitting (Kalkhoran & Glantz, 2016). Finally, a recent systematic review/meta-analysis of e-cigarettes for smoking cessation reported a smoking cessation rate of 13.2–22.9% (Liu et al., 2018). With few randomized, controlled trials having been published, there is insufficient evidence that ECIGs help smokers quit (El Dib et al., 2017; Siu, 2015). Further, interpreting results from the existing studies is complicated by the variations of ECIGs as a product class: as all ECIGs are not the same, drawing sweeping conclusions across the entire product class is difficult.

The authors are not aware of any published clinical trial research on ECIGs for smoking cessation for pregnant women in the United States. Although some cautiously recommend ECIGs for pregnant women (UK’s Smoking in Pregnancy Challenge Group, 2018), others do not (Centers for Disease Control, American College of Obstetricians and Gynecologists) due to concerns about nicotine and other toxicant delivery. Concerns about nicotine/other toxicant delivery are described briefly below.

6 |. DO ECIGS DELIVER NICOTINE AND OTHER TOXICANTS?

The safety of ECIGs has been fiercely debated in the scientific community. Overall, there are concerns about nicotine delivery, as well as other toxicant delivery from the liquid vehicles (propylene glycol and vegetable glycerin), liquid flavors, and metal device components. Some toxicants are lower in exclusive ECIG users compared to cigarette smokers, such as the tobacco-specific nitrosamine metabolite NNAL, a known carcinogen in combustible tobacco products (Goniewicz et al., 2017; Hecht et al., 2014; Weaver et al., 2016). In addition, ECIGs appear to not deliver carbon monoxide (CO; e.g., Weaver et al., 2016); CO is particularly harmful to a developing fetus (Aubard & Magne, 2000). However, many ECIG users are “dual users,” that is, they use both combustible cigarettes and ECIGs; these dual users are still exposed to toxicants (e.g., Goniewicz et al., 2017; Pulvers et al., 2018). Similarly, dual use of cigarettes and ECIGs during pregnancy is also likely harmful for pregnant women due to the delivery of CO and other toxicants, as described below. Further, dual use has the potential to increase nicotine exposure (Whittington et al., 2018).

Nicotine, the dependence-producing drug in ECIGs, is a toxicant of particular concern for pregnant women, as nicotine is known to harm a fetus (e.g., Bruin, Gerstein, & Holloway, 2010; England et al., 2016) some have suggested that no amount of nicotine in pregnancy is safe (CDC, 2016; Suter, Mastrobattista, Sachs, & Aagaard, 2015). ECIGs differ dramatically in terms of their nicotine delivery, with some products delivering little to no nicotine (e.g., Farsalinos et al., 2014; Vansickel et al., 2010; Yan & D’Ruiz, 2015), and others delivering as much, or more, than a combustible cigarette (e.g., Ramoa et al., 2016; St. Helen, Havel, Dempsey, Jacob III, & Benowitz, 2016; Wagner et al., 2017). This variation is the result of many factors, such as user behavior (e.g., Hiler et al., 2017), device power settings (Wagner et al., 2017), liquid concentration (Hiler et al., 2017), and solvent ratio (propylene glycol and vegetable glycerin; Spindle et al., 2018).

Some work in animal models has suggested that there is reason for concern about other ECIG toxicants as well. For example, in a frog embryo model, an ECIG aerosol mixture with or without nicotine caused facial clefts (Kennedy, Kandalam, Olivares-Navarrete, & Dickinson, 2017). Other researchers have also reported that ECIG aerosol, with and without nicotine, can result in concerning changes; using a mouse model, ECIG aerosol caused changes in gene expression (Lauterstein et al., 2016). Other mouse models have also shown detrimental effects of ECIG aerosol exposure (with and without nicotine) in offspring, such as markers of lung health (Chen et al., 2018). In another study, mice exposed to ECIG aerosol (with nicotine) for the first 10 days of life led to some impaired lung growth (McGrath-Morrow et al., 2015). A study by Nguyen et al. (2018) found that the offspring of mice exposed to ECIG aerosol had a variety of detrimental outcomes, both cognitive and epigenetic. Finally, a recent study of in vivo changes in mice found that ECIG exposure resulted in decreased fetal weight and length (Orzabal et al., 2019). For a more thorough description of the developmental toxicity of ECIGs, please see the accompanying article in this issue by Greene and Pisano.

7 |. LIMITATIONS OF EXISTING RESEARCH

There are many limitations to existing research, as described in a recent report by the National Academy of Sciences (NAS, 2018), such as a lack of dose–response studies in the animal literature, as well as the difficulty comparing nicotine exposure in animal studies to human exposure. In addition, research in human participants (i.e., cohort studies of pregnant women, case reports or other clinical studies) is nonexistent (NAS, 2018; Orzabal et al., 2019; Orzabal & Ramadoss, 2019). Further, among studies examining biobehavioral factors of ECIG use, most rely on self-reported information for cigarette and ECIG use (cigarettes per day, frequency of use, nicotine concentration in ECIG liquid, etc.) which may impact interpretability. Finally, most surveys do not ask about the type of ECIG used, or the power level of the device, also limiting interpretability of results.

Overall, the literature is scant in this topic area. To illustrate, a recent search of PubMed articles conducted on June 26, 2019 ((((((“electronic cigarette”[Title/Abstract] AND pregnancy [Title/Abstract]) OR “e-cigarette”[Title/Abstract]) AND pregnancy[Title/Abstract]) OR “electronic nicotine delivery systems”[Title/Abstract]) AND pregnancy[Title/Abstract]) OR JUUL[Title/Abstract]) AND pregnancy[Title/Abstract], and after removing unrelated articles, revealed a total of 48 articles. One was published in 2011; three in 2014; seven in 2015; eight in 2017; six in 2018; and four thus far in 2019. (Not all of the articles from this search were discussed in this paper). While this search did not include all of the published literature on ECIGs and pregnancy (i.e., not all the papers in this manuscript appeared in the search), it highlights the need for additional work in this important area of public health.

8 |. HOW COULD NEW ECIGS LIKE JUUL AFFECT PREGNANT WOMEN?

ECIGs such as JUUL, Suorin, Phix, and Bo are sometimes referred to as “pod mod”- style ECIGs. Of this subclass, JUUL sales now make up 40% of the e-cigarette market (Huang et al., 2019), and due to dramatic online sales to youth, JUUL was recently cited by the FDA for targeting youth (Knopf, 2018). JUUL ENDS or ECIGs are different from other ECIGs because the liquid in the pods has a very high nicotine concentration (advertised as 5%, or ~50 mg/mL; independent testing has shown that pods can have as much as 68.6 mg/mL nicotine; Talih et al., 2017). According to JUUL Labs, each pod is equivalent to one pack of cigarettes, or 200 puffs. Also, the nicotine is mostly protonated, or salt-based, instead of the free-base nicotine present in many other types of ECIGs. Because protonated nicotine has a lower pH, this form of nicotine may be easier to inhale (Talih et al., 2017). Research from JUUL Labs indicates that this product can deliver nicotine in cigarette-like quantities (Wynne, Waaka, & Cohen, 2018). In addition, a recent study of adolescent “pod mod” users showed higher levels of the nicotine metabolite cotinine, compared to a separate study of regular adolescent cigarette smokers (Goniewicz, Boykan, Messina, Eliscu, & Tolentino, 2018). As described earlier, adolescents, as well as pregnant women, are more likely to be negatively impacted by nicotine due to the effects of nicotine on the developing brain, and thus, JUUL use is particularly alarming. Currently, the effects on pregnant women and fetuses of inhaling nicotine salt aerosols is unknown.

As previously indicated, the PATH study has generated significant data regarding tobacco-use patterns, initiation, risk perceptions, and attitudes toward current and emerging tobacco products, although JUUL use had not been separated from other ECIG use (in data currently available through Wave 3). To complicate matters, based on an 2018, national online study (n = 1,012) examined perceptions of JUUL use in those 15–24 years old, results indicated nearly one-third of participants did not refer to JUUL as an electronic cigarette (Willett et al., 2018). To our knowledge, there is no research on the health effects of JUUL use on perinatal outcomes. As most electronic cigarettes, including JUULs, contain nicotine, coupled with the safety implications associated with the teterogenic effects of nicotine on fetal development, use during pregnancy should not be recommended.

9 |. CONCLUSIONS

In conclusion, ECIGs are products which can deliver nicotine and other toxicants, and which women of reproductive age, and some pregnant women, are using. This use is concerning as nicotine and other toxicants in these products may harm a developing fetus. Further, ECIG use among pregnant women is correlated with current cigarette smoking, and there is insufficient evidence to show that ECIGs can help smokers quit smoking. For these reasons, the authors do not recommend that pregnant women use ECIGs.

The perceptions among some pregnant women that ECIGs are less harmful than cigarettes, and that they are associated with smoking cessation, are also concerning, as these perceptions are in contrast to much of the scientific literature thus far. In addition, healthcare providers have mixed perceptions of ECIGs in terms of safety and as a smoking cessation aid. Together, these perceptions among pregnant women as well as healthcare providers highlight the need for both groups to receive clear, accurate information about these products. To help healthcare providers identify ECIG users, all forms of novel tobacco products, including ECIGs, should be included on patient forms and assessments. These need to be updated regularly, as terminology and products can change quickly. At the same time, smoking cessation during pregnancy should be encouraged, and healthcare providers must also continue to use methods such as the “5 As” brief intervention (ask, advise, assess, assist, arrange; Fiore et al., 2008) and have training and/or referral information on smoking cessation methods which are safe for pregnant women, such as behavioral interventions.

Overall, while ECIGs appeared in the United States in the mid-2000s, more than a decade later, scientists struggle to agree on the health effects of ECIG use. More importantly, the delay in evidenced-based research related to ECIG use may be a contributing factor in delayed product regulation, unrealistic perceptions of ECIG safety, and an increased uptake among vulnerable populations including pregnant women. The current review confirms that important work is being done, and points readers to relevant, up-to-date findings related to what ECIGs are, use prevalence, current research on ECIG use in pregnancy, healthcare providers’ perceptions of ECIGs, ECIGs and smoking cessation, and nicotine and other toxicant delivery associated with ECIGs. In this rapidly changing landscape, researchers and providers must keep abreast of new products, use rates, and research findings and highlight limitations or gaps in the field in order to continue moving policy development and product regulation forward.