Comparison of adverse Pregnancy Outcomes between Hookah and Non-smoking Women

Introduction

Globally, the increase in tobacco use is a critical issue. The World Health Organization (WHO) estimated that tobacco consumption annually caused 6,000,000 deaths worldwide (1). Nowadays, hookah smoking is considered as one of the increasing global problems, especially in the countries of the Eastern Mediterranean such as Arab countries, Turkey, and Iran (2).

Women are considered as one of the main pillars of family. Therefore, the development of a disease in them and its complications, especially during pregnancy, are associated with adverse consequences such as neuropsychiatric disorders in children, fetal abnormalities, infantile diseases, and severe economic impacts. In addition, this issue may affect the society by incurring huge costs, using specialized staff and equipment for the treatment of these complications, and bearing the burden of social problems resulting from these disorders (1).

Recent epidemiological studies indicated that in some of the aforementioned regions, the prevalence of hookah smoking has increased in the populations, many of whom are women, children, and adolescents (3). The results of a study conducted in one of the Arab countries showed that 70% and 50% of male and female students smoke hookahs, respectively (4).

According to the literature, hookah exposes users to the high concentrations of carbon monoxide, nicotine, tar, and heavy metals (5). There are little researches carried out into the effects of hookah smoking on health status. Nevertheless, initial evidence indicates a relationship between hookah smoking and the incidence of a variety of diseases including respiratory and cardiovascular diseases, cancer, and dermatitis (1, 6).

Perhaps hookah smoking is the only way of tobacco consumption, which is common among Iranian women and socially accepted to some extent with unfortunately increased use among women and adolescents in recent years (2). On the other hand, the adverse effects of hookah were not well investigated as compared to those of cigarettes. The main reason is that hookah smoking is not among the habits of Western societies, while cigarettes are very common in the West (2).

So far, few studies have been conducted in Iran on the complications of hookah smoking. Additionally, only some of them have dealt
with investigating its complications during pregnancy that reported its significant relationship with low birth weight (7). Nonetheless, many studies confirmed the adverse effects of cigarette smoking during pregnancy including the risk of hypertension, stillbirth, placental abruption, and low birth weight (5, 8).

Preeclampsia is now considered as the most common medical problem during pregnancy (9). It was reported as one of the three main causes of maternal and neonatal mortality worldwide. Meanwhile, its prevalence in Iran is higher than the global average (10). Preterm labor is one of the serious obstetric complications, which occurs in about 7% of pregnancies (11).

However, a higher prevalence of up to about 20% was reported in Iran, which was associated with neonatal mortality in 70% of the cases (10). Further, low birth weight is considered as another serious neonatal complication. Although its global prevalence is 6%, it has a minimum prevalence of 8% in Iran (6). In this regard, the WHO recommended further studies to find the relevant variables (12).

Intrauterine demise, with a global prevalence of 1% is one of the tragic obstetric incidents that reaches 2.2% in Iran (12). The above-mentioned complications impose a heavy economic burden on the society in addition to reducing the health indices. As a result, it is essential to conduct researches on the relevant factors. It is worth mentioning evidence revealed the relationship of all the above-mentioned complications with cigarette smoking (11, 12, 13). Therefore, this study was conducted to compare maternal and neonatal outcomes of pregnancies between women smoking hookahs and women non-smokers.

Materials and Methods

This study was conducted in the form of a 13-month prospective cohort study from late March 2014 until late April 2015 with the approval of the Research Committee of Islamic Azad University, Falavarjan Branch under the code No. 5172. In the present study, hookah smoking was the independent variable, and preeclampsia, preterm labor, intrauterine demise, placental abruption, low birth weight, and 5-minute Apgar score were the dependent variables.

The study population consisted 512 pregnant women referred to healthcare centers in Isfahan, 2014, to receive prenatal care services. The samples were divided into two groups of smokers and non-smokers (256 individuals per group). The samples were selected through convenience sampling method. The subjects were followed up from the 24th week of pregnancy until the post-partum.

The sample size is necessary for comparing the binomial ratio taking into account the time, cost, and generalizability, and through the one-way test at a significance level of α=5% and a power of 1-β=0.08 (p₁). The probability of observing the complications of pregnancy in Iranian pregnant women smoking hookahs, which was 0.16 based on the conducted study (p₂), was calculated through substituting the values in the following equation (14).

The inclusion criteria entailed the Iranian race and gestational age less than 24 weeks (for preeclampsia follow-up). Prior to the study, a written informed consent was obtained from each participant. In addition, the exclusion criteria included the history of diabetes, oligohydramnios or polyhydramnios, multiple births, hydatidiform moles, hydrops fetalis, intrauterine demise, chronic hypertension, surgery during the current pregnancy, Rh incompatibility, placenta previa, cervical incompetence, uterine abnormalities, fetal anomalies, placental insufficiency, premature rupture of membranes, as well as positive history of cardiac, renal, and infectious diseases, and cigarette smoking.

Data were collected using a questionnaire and through interviewing and examination. The questionnaire consisted of 34 questions divided into three parts. Parts I and II (the demographic and hookah smoking information) were completed during sampling. The third part was related to obstetric complications, which was completed by referring to the mothers’ obstetric record and through the examination of the newborn.

A test-retest method was used to measure the reliability of the questionnaire. To perform the test-retest, the questionnaires were administered to 10 members of the study population including five hookah-smoker pregnant women and five non-smoker ones. They completed the questionnaires; then, within a week, the questionnaires were re-completed by the same people but different questionnaire.

Thereafter, every single question in the first test was compared with that in the retest, and because the correlation coefficient between the first and second tests was higher than 0.7 in each part, the questionnaire was approved. The first and second parts of the questionnaire were completed, and the respondents’ addresses and phone numbers were recorded for future follow-up.

The case group was divided into three subgroups of light smokers, with a maximum smoking rate of twice a week, moderate smokers with a smoking rate of twice to seven times a week, and heavy smokers with a smoking rate of more than once a day. The control group consisted of the pregnant women referred to the same centers with no history of hookah smoking (before or during pregnancy), and who were matched to the case group in terms of age, parity, weight at the beginning of pregnancy, and family history of preeclampsia. The first part of the questionnaire was completed for this group, as well.

The subjects’ estimated dates of delivery were recorded. Both the case and control groups were asked to inform the researcher by phone immediately after entering the maternity ward for delivery. Additionally, they were asked to contact the researcher as soon as possible in case of emergency childbirth, pregnancy loss, hypertension, or proteinuria. To remind the subjects of following-up the issues, they were contacted by phone during the second and third trimesters of pregnancy. While renewing the previous appointment, the questions were asked of them about the symptoms or diagnosis of preeclampsia.

The interviewers, who all were midwifery experts, attended the maternity ward on the date scheduled for the subjects’ deliveries and completed the third part of the questionnaire through observation, maternal and neonatal examinations, and their obstetric records. This process continued until the sampling was completed. Data analysis was performed using descriptive and analytical statistics including Chi-squared, t-test, Mann-Whitney U and Fisher’s exact tests with the aids of the SPSS software, version 19.

Results

This study was conducted among a total of 512 pregnant hookah smokers and non-smokers. The groups were matched in terms of age, parity, weight at the beginning of pregnancy, and family history of preeclampsia. None of the subjects were excluded from the study. The demographic characteristics of the subjects are shown in Table 1. Out of 256 subjects in the case group, 58, 87, and 111 subjects were heavy, moderate, and light hookah smokers, respectively.

In addition, 55 (22.65%) and 28 (10.93%) subjects in the case and control group were affected by preeclampsia, respectively. Fisher’s exact test was used to determine the relationship between preeclampsia and hookah smoking. In this case, the two-way significance level for Fisher’s test was approximately zero. Therefore, at an error level of 5%, the assumption of independence between hookah smoking and preeclampsia was rejected (P<0.001).

It means that hookah smoking might change the risk of being affected by preeclampsia. Given the results, the risk of preeclampsia in hookah smoker women was 4.11 times more than that of non-smokers. Additionally, 41.3%, 59.7%, and 54.05% of heavy, moderate, and light hookah smokers reported preeclampsia, respectively. There was no significant relationship between the light, moderate, and heavy levels of hookah smoking and preeclampsia in the case group (P=0.1).