Introduction

The global prevalence of past-year drug use among people aged 15-64 years is estimated at 4.8% in 2018, which had an increasing rate of 28% compared to 2009 (1). In the Middle East, the prevalence of substance use disorder is 1.3 times that of the world (2). In Iran, one of the countries in the Middle East, the situation is worse, as opium use has been reported up to 3 times the global average (3). Kerman, a city located in the south-east of Iran, is the center of the biggest province of Iran with a population of 800000. Opium consumption is rooted in the history of Kerman. It is one of the most prevalent areas of opium use in Iran (3).

  Women and men are more likely to use drugs at a young age, which means that women of childbearing age are at greater risk for substance abuse disorders (4). In 2012, half of the US women of reproductive age reported current use of alcohol, and 13% used other drugs (4).

Substance use among pregnant women is widely recognized as a significant public health threat (5). It can cause many problems for the fetus, including neonatal abstinence syndrome, low birth weight, and preterm labor (6). Substance use is also associated with poor prenatal care during pregnancy and fear of disclosing (7).

A recent review of 70 articles showed that the prevalence of illicit drug use among pregnant women ranged from 1.65% (based on self-report) to 12.28% (based on toxicological analysis) (8). Most of the studies conducted in Iran on the prevalence of substance use in pregnant women have been based on self-reporting (9, 10). Furthermore, the use of the questionnaire is not acceptable owing to the underreporting due to fear and stigma among pregnant women (11). The only study which used a urine drug screen had a small sample size (12).  Considering the high risks of drug use in pregnancy and the high prevalence of drug use, especially opium, in the South East of Iran, this study was performed to determine the prevalence of substance use among pregnant women and its related factors in Kerman as a hot spot for substance use disorders. The present study could be informative for policy-making and research in high-risk pregnancies.

Materials and Methods

This cross-sectional study was performed in the first half of 2020 at the referral laboratory of Kerman District Health Center. Kerman is the center of the biggest Province of Iran, located in the South East. The reason for choosing this center was that pregnant women from all areas of Kerman province are referred to public health centers for routine pregnancy blood and urine tests.

Inclusion criteria were age higher than 15 years and exclusion criteria were unwillingness to participate in the study. Sample size was calculated considering 95% CI and 5% prevalence rate of drug use and the power of 80%. A total of 1000 consecutive pregnant women were invited to participate in the study. Finally, 966 subjects agreed to be included in the study (96.6% response rate). The content validity of the checklist was approved by an expert panel. The inventory consisted of demographic (age, education, occupation, place of residence, and socioeconomic status) and obstetric characteristics (gestational age, parity, and the number of children). The socioeconomic status of the subjects was categorized into two levels (low and middle to high) based on their neighborhood status (13).

 After explaining the purpose of the study to the women and obtaining their consent, a urine sample was taken. An aliquot of the redundant urine sample of pregnant women was coded, and testing was done anonymously. Also, the background data checklist was anonymously completed at the same time. More prevalent drugs in the Iranian community were considered (14).

Urine drug testing was done in two stages: (a) A qualitative screening test using the rapid immunoassay method (15), (b) Thin-layer chromatography (TLC) was used to confirm the initial positive results (16). All test steps were performed according to the kit instructions (Rojan Azma Company, Tehran, Iran) to detect morphine/opium, amphetamine, methamphetamine, buprenorphine, tramadol, methadone, and Marijuana. The sensitivity of the kit was 300 ng/ml for morphine and methadone, 500 ng/ml for amphetamine and methamphetamine, 10 ng/ml for buprenorphine, 100 ng/ml for tramadol, and 50 ng/ml for marijuana.  TLC method as a widely available and reliable confirmation test has been established to confirm rapid immunoassay tests (17).

Chi-square test was used to compare categorical data between the groups. Multivariable logistic regression analysis was done to examine the association between the result of the urine screen test and the independent variables. Independent variables with P> 0.25 in bivariable analysis were included for further multivariable analysis. Data were analyzed by IBM SPSS Statistics software (version 22). P<0.05 was considered statistically significant. 

Results

Mean age of participants was 27.3±6.6 years. Other demographic and clinical characteristics of pregnant women were shown in Table 1.

In total, 7% (95% CI: 5.4–8.7) of pregnant women (n=68) used drugs.  Opium was the most frequently used drug (Table 2). The prevalence of drug use by baseline characteristics was shown in Table 3.  The two variables which showed significant association with drug use during pregnancy were age higher than 35 years (odds ratio=1.05; CI 95%:1.01-1.09) and low socioeconomic class (odds ratio=2.23; CI 95%:1.33-3.74).

Discussion

The results of the present study showed that the prevalence of drug use among pregnant women was 7.0%.

The prevalence of drug use in the present study was much higher than the results obtained from the nationwide research (1%) (10) or the studies conducted in other Iranian cities (1.5%) (18). Three reasons could be responsible for the high percentage of drug use in the present study. First, other studies have used the self-report method. Fear of punishment and stigma leads pregnant women to conceal drug use (7). This fear may be more pronounced in countries such as Iran with anti-drug policies (19). Accordingly, the use of self-report to determine the prevalence of substance use in pregnancy is not recommended (11). A recent review showed that the prevalence of drug use among pregnant women is 7.4 times higher in studies utilizing laboratory methods compared to those that relied on self-report (8). Second, Kerman, where this study was conducted, is one of the most prevalent areas for substance use disorders in Iran (3). A recent study stated that the prevalence of opium use in Kerman is 3.5 times the national average (20). A survey conducted with a similar method (urine screen test) on adult population of Kerman revealed that 14.4% of urine samples were positive for opioids (16). Third, since the present study only included public sector clients, the upper socioeconomic classes participate less in the study. It has been proven that substance use is more common in the lower socioeconomic classes (3). Tavella et al. (2020) reported that the total prevalence of worldwide illicit drug use during pregnancy (using the weighted average of the 70 studies) was 1.83%, and this rate is higher in Asia (6%) than in other continents (8).

Opium was the most frequently detected drug in the urine samples in the present study. Considering opium, methadone, and buprenorphine as opioids, it can be concluded that 97.1% of the positive results were related to opioids. Considering the potential harms of opioid use during pregnancy on neonatal health outcomes, policymakers should seriously consider this issue (21). No pregnant woman tested was positive for marijuana. In a study in Spain, the most common substance detected was marijuana, and no one tested was positive for opioids (22). In the US studies, marijuana was the most commonly detected drug among pregnant women (23). This finding shows that the pattern of drug use in pregnant women follows the practice of the general population.

Multivariable logistic regression analysis showed that living in a low socioeconomic neighborhood was linked to a higher rate of drug use during pregnancy. This finding is in line with the study results from the US (24) and Canada (25). That's why the expert panel from countries with a lower prevalence of substance use in pregnancy recommends universal drug screening during pregnancy (5). Higher age was another risk factor that increased the possibility of drug use as part of routine. It may be due to having more opportunities to consume drugs during the time. It may be warranted to request urine drug test as part of the routine screening programs of pregnant women higher than 35 years old in areas where drug use is more prevalent.   

Some strengths of this study were the large sample size and the use of toxicological analysis to determine the prevalence of substance use in pregnant women.

The main limitation of this study was that it did not include private sector clients.

Conclusion

The results of the present study revealed that the prevalence of opioid use is high among pregnant women in southeastern Iran. The concern was more evident especially in women over 35 years and in the lower socioeconomic classes.  

Declarations

Acknowledgements

We thank to all pregnant women who accepted to participate in our study.

Conflicts of interest

  The authors declared no conflicts of interest.

Ethical considerations

Before enrolling of women in the study, the objectives and method of the study were explained to the pregnant women. They were assured about complete confidentiality and anonymity (anonymous unlinked testing). All participants signed the written informed consent.

Ethical approval

The study protocol was approved by Ethics Committee (approval code: IR.KMU.REC.1401.116)

Funding

   The study was supported financially by Sepehr Clinical Laboratory (Kerman).

Authors’ contribution

   MG and NN contributed substantially in the conception and design of the study. HG carried out the data collection and analysis. NN analysed and interpreted the data. MG drafted the manuscript. NN and HG reviewed the manuscript critically for important intellectual content. All authors read and approved the final manuscript and agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.