To the best of our knowledge, there is a dearth of studies on the relationship between individual SES and SHS exposure at home among pregnant women in the 3rd trimester in China. This study not only provided insight into the status of SHS exposure but also examined this relationship with SES. Unemployment and high school or technical secondary school educational attainment had significant effects on SHS exposure. In the present study, we found that an unstable marriage (cohabiting relationship) and college or above education level were associated with an elevated and decreased risk of SHS exposure enhanced by age.
The finding showed that the current SHS exposure prevalence from this study was 35.1%, which was lower than that of a previous national-level study from 2013 (47.2%) . The prevalence of SHS exposure in this paper was also lower than that reported in prior population-based studies conducted in Henan Province and Sichuan Province. Overall, 60–70% of pregnant women experienced SHS exposure, and 75.1% of nonsmoking pregnant women suffered from chronic SHS exposure from their respective spouses [4, 27]. As a previous study reported, higher probabilities of SHS exposure occurred in low- and middle-income countries . It could be perceived that the rate of SHS exposure among pregnant women varied by region, with some locations having a high level of exposure but other regions having a low level. China is the country with the most tobacco production and consumers in the world, and approximately 47.2% of males had smoking habits in an investigation conducted in 2013 . Tobacco plays a very important role in China’s economics and culture. The government has tried to encourage adults to give up tobacco, but a great number of males still have smoking habits in China. Overall, smoking was a widely acceptable behavior in China, although SHS has become a major public health problem and has caused a heavy burden of disease worldwide . Exposure to SHS during pregnancy was common in the pregnant women population.
Our results are in line with prior studies [15, 29] showing that women’s higher educational attainment was an independent protective factor for reducing SHS exposure. Education is one aspect of the basic drivers of human behavior that can promote healthy behavior and keep individuals away from harmful exposure . Generally, pregnant women who are more educated have greater awareness of tobacco and reduced exposure. Meanwhile, the availability of various medical and economic resources may depend on educational attainment. Thus, educational attainment can be regarded as a vital determinant of SHS exposure. In our study, we also confirmed that unemployed participants had a greater risk for SHS exposure. Employment and education were strongly associated, and both have impacts on household income and the social conditions of resources. Previous studies have shown that unemployment or manual labor are predictors of maternal SHS exposure during pregnancy [24, 31, 32]. Participants who were more educated were more likely to have steady jobs, which increased the likelihood of engaging in healthy behaviors and actively staying away from harmful exposures . Conversely, unemployed women have limited health education resources, low awareness of the harms of exposure to SHS and a self-perception of relatively low status within the family, increasing the possibility of SHS exposure. Interestingly, we found that lower personal income per month might be considered a protective factor for SES exposure, which might reflect a shift in the association between income and SHS exposure. These observations supported those of previous studies conducted by Receea et al. and Mahmoodabad et al. [2, 19] but contradicted the evidence from Yang and colleagues . Nevertheless, as far as we are concerned, after adjustment for related background variables, there was no significant association between income and SHS exposure. The reason behind whether high income increases the risk of SHS exposure among pregnant women is still undetermined, and further research will be needed to explain this phenomenon. The significant results in our findings indicated that those women who were exposed to SHS were often less educated and unemployed.
Notably, age influences the relationship between a higher level of educational attainment and unstable marital status, that is, lower level of SES increased the risk of exposure to SHS. Currently, several studies have indicated that age was a potential mediator to SHS exposure. Younger women were more likely to be exposed to SHS [17, 34–36], but in the study by St Helen et al., women aged over 35 years had higher levels of UC (urinary cotinine) due to SHS exposure at home . However, the combined effects of age and individual’s SES on SHS have not been studied previously. This modification effect is plausible because SES is a fundamental cause of disease because it is closely associated with access to important resources and affects multiple disease outcomes through multiple mechanisms . However, the capacity to use resources to gain a health advantage is increasingly weak in populations with relatively low levels of SES with age. In particular, women were expected to be obedient to their spouse in families with traditional Chinese cultural backgrounds. It could be speculated that pregnant women with a lower level of educational attainment and an unstable marriage were less likely to change the smoking behavior of their spouse/partner, and exposure to SHS might occur more frequently.
Avoiding SHS exposure during pregnancy is an important health priority for health care professionals and policy-makers. However, researchers have stated that it is still difficult to eliminate SHS exposure during pregnancy in LMICs, China included. First, the awareness of harmful outcomes attributed to SHS exposure was lower in LMICs . Second, pregnant women may not argue with males due to the existence of a male-dominated ideology, even though they have already realized the risk of SHS exposure . Importantly, although smokers tried to avoid direct contact with pregnant women, SHS was much more difficult to avoid. One important reason was that the hidden demon called “thirdhand smoke (THS)” still remained in the environment, especially on skin and clothes, which poses a new threat to pregnant women; nonetheless, the risk of THS is rarely known by pregnant women and their family members . In addition, family consensus on smoking bans may be an effective strategy , as in pregnancy, women are well protected in the family, particularly by their spouse/partner, who values their advice. In summary, it is imperative for both pregnant women and their spouse/partner to be included in interventions for tobacco control and the ongoing implementation of SHS prevention and pregnancy health education.
Some limitations of this study should be recognized. First, the status of exposure to SHS was determined using participants’ self-reports, which might have led to a recall bias of the measurement effect of SHS to some extent. However, prior investigations found that measuring SHS exposure by self-report is still a satisfactory and acceptable approach to determining SHS exposure and is widely used in an increasing number of studies . This cross-sectional study had practical limitations in terms of causal inference. Longitudinal and qualitative research is needed to help identify the association between SHS exposure and SES. In addition, the spouse/partner’s SES also partially explained the association between SHS exposure and social status . However, no significant differences were observed between these SES variables of the spouse/partner in terms of group comparison analysis. Last, we only took the spouse/partner as an account for sources of SHS exposure. However, we considered that the contribution of other sources of SHS, such as workplaces and restaurants, was negligible, given that pregnant women generally spend most of their time with spouses/partners during pregnancy.
In summary, risk perceptions and communication were related to SES , which could suggest that SES may have practical applications to smoking cessation implementation. Pregnant women are a key subpopulation that should implement tobacco control efforts for their spouse/partner because both cigarettes and smokeless tobacco pose serious threats to the mother and fetus. This paper’s results indicated that, to a certain extent, a lower level of SES leads to a higher likelihood of SHS exposure. An educated spouse can change their smoking behavior and protect the health of pregnant women.