Document Type : Original Research Article
Author
Associate Professor, Health Sciences Research Center, Department of Occupational Health Engineering, School of Health, Mashhad University of Medical Sciences, Mashhad, Iran.
Abstract
Keywords
Introduction
Psychological stress is one of the important risk factors for reproductive disorders about which, few studies have been conducted (1). However, there are plenty of studies on the environmental risk factors for reproductive disorders such as occupational risks (2-5). It is suggested that exposure to some physical factors such as ionizing radiation and electromagnetic fields can cause the reproductive disorders. Exposure to chemicals can also affect reproductive system, especially pregnancy outcome (2).
Sznajder et al. investigated gynecological pain associated with occupational stress among female factory workers (3). Some studies such as Larsen et al.’s study demonstrated psychosocial job strain as a risk factor for congenital malformations in pregnancy outcomes (4, 5). Another study was carried out on the effects of stress on rural pregnant women. It was found that they had some stressors, and priorities for stress reduction (6).
Some studies were conducted on physiological effects of working on women. Bilhartz and Bilhartz suggested that occupation could be a risk factor for hypertensive disorders in pregnancy (7). Reza et al. showed the prevalence of female health disorders related to psychological stress (8). Some other studies have investigated the role of maternal stress in congenital malformations and disorders in children; for instance, van Dijk et al. studied the relationship between prenatal stress and the balance of a child's cardiac autonomic nervous system at 5-6 years of age (9). Robinson et al. demonstrated the relationship between the prenatal stress and the risk of behavioral morbidity from age 2 to 14 (10). Moreover, van Dijk et al. demonstrated the cardio-metabolic risk in 5-year-old children, who were prenatally exposed to maternal psychosocial stress (11).
Larsen et al. studied the association between psychosocial job strain and adverse birth outcomes (12). Han et al. demonstrated the relationship among occupational stress, negative life events and low birth weight (13). Howell et al. determined the modifiable factors associated with changes in postpartum depression symptoms (14).
Goodman and Tully showed the recurrence of depression during pregnancy in accordance with psychosocial and personal functioning correlates (15).
Some scientists studied mothers’ mental and physical background during pregnancy and the effect of fatigue on the outcome (16-19). It was found that musculoskeletal disorders were related to mental stress and they had a significant relationship with reproductive outcome (20). Physicians themselves had experienced this situation that is, they had suffered from stress and the related disorders (21).
Shift working is an important risk factor for disrupting the circadian rhythm (22-24), which is related to mental disturbances. Some other studies investigated the effects of shift working on health (25, 26). Given the fact that the exact effect of psychological stress on reproduction remains unknown, the aim of this study is to determine the effects of women’s psychological stress on obstetric disorders.
Materials and Methods
This historical cohort study was performed on 1400 working women with different jobs from different workplaces in Iran during 2010-2014. The participants were selected through random clustered sampling from different settings. According to previous studies in this field, α= 0.05, β= 0.80, P1=15% and P2= 45%, for reproduction disorders in women without stress and with stress (2, 29).
The inclusion criterion was women who had been employed for at least three years. Moreover, the exclusion criteria were: experiencing previous preterm delivery, placental abruption, premature rupture of membrane, fetal defect, low birth weight, infertility, menorrhagia, spontaneous abortion, before they had begun their job or had psychological disorders.
Moreover, these women were assessed for not having any physical or chemical exposures and ergonomic or mechanical risks such as standing for long periods of time while working.
Psychological stress was evaluated using the Work Environment Scale, which is a standard scaling checklist (27-29). The dimensions of the checklist consisted of decision making, mental requirement, changing, career development, tasks, responsibility, harmony with coworkers, quality of supervision, aims and goals, role as a special or general worker or employee in shift work. There were ten levels of occupational stress with ranging from 1 to 10.
After taking oral consent from the participants, the questionnaire was filled out. Subsequently, using the collected data, the participants were divided into four groups as follows: group +1: mild, group +2: moderate, group +3: moderate to severe and group +4: severe to very severe psychological stress, and the stress grades were: group +1: 25%, group +2: 26-50%, group +3: 51-75% and group +4: 76-100%.
Questionnaire design
The questionnaire was designed using interviews with 1400 working women. To assess the validity of the questionnaire, 32 health and medical sciences professors from different universities gave their opinions regarding the items of the questionnaire, then a pilot study was performed with 30 people and showing correlation coefficient of 86% (2).
This questionnaire included items on preterm delivery, placental abruption, premature rupture of membrane (PROM), infertility, spontaneous abortion, fetal defect and low birth weight. The questionnaire also determined the occupational and non-occupational risk factors for reproductive disorders. Non-occupational risk factors include age, body mass index (BMI), family history, gynecological and endocrine disorders, and occupational risk factors consist of occupational psychological stress, exposure to chemical and physical factors and shift work.
The four groups were observed for gravidity and age. The data were collected using a checklist (Work Environment Scale) and a self-regulated questionnaire on health issues. The researcher explained all the items of the questionnaire for the participants. Moreover, the pregnancies were followed-up.
Statistical analysis
Data were analysed performing descriptive analysis, t-test and ANOVA for quantitative variables, Chi-squared and Fisher’s exact tests for qualitative variables and Mantel- Haenszel test was used for controlling age groups, cross tabulation and determination of relative risks, using SPSS, version 16. P-value less than 0.005 was considered significant.
Results
It was found that group +1 had the highest mean age, which was 34.06±3.96 years, and the lowest mean age was in group +4 with 26.32±1.82 years. The longest working hours belonged to group +1 with 12.33±3.68 hours and the shortest was for group +4 with a mean of 6.59±1.26 hours. There was a significant difference between the two groups (P<0.05). BMI was 24.02±0.40 in group+1, which was the highest among the four groups. Table 1 shows the mean and a comparison of variables among the four groups.
Table 2 shows the comparison of reproductive disorders among the four groups. Preterm delivery was more frequent in group +4, and the rates of spontaneous abortion and low birth weight were higher in group +1; however, the difference between the two groups was not significant. Table 3 demonstrates the different risks for obstetrics disorders for each group.
After deletion of age group effect, the relative risk for spontaneous abortion and placental abruption was found to be significant in group +4. The relative risks for spontaneous abortion and placental abruption were 2.63 (1.09-6.31) and 4.29 (1.85-9.95), respectively.
Table 1. Mean of variables and comparison of the four groups with graded psychological stress (P<0.05)
|
Variables |
Group 1 µ±SD |
Group 2 µ±SD |
Group 3 µ±SD |
Group 4 µ±SD |
ANOVA(F) |
P-value |
|
Age |
34.06±3.96 |
27.20±3.82 |
30.00±9.98 |
26.32±1.82 |
107.46 |
<0.001 |
|
Work duration |
12.33±3.68 |
7.86±2.19 |
8.00±2.82 |
6.59±1.26 |
71.57 |
<0.001 |
|
Body mass index |
24.02±0.40 |
22.00±0.1 |
22.10±0.1 |
22.06±0.39 |
35.71 |
0.07 |
|
Age at disorder |
24.50±5.26 |
23.04±1.23 |
23.12±3.01 |
22.03±1.20 |
24.65 |
0.08 |
|
Gravidity |
2.2±0.5 |
1.65±0.77 |
1.5±1.4 |
1.5±0.78 |
22.52 |
0.9 |
Table 2. Comparison of reproductive disorders among the four groups with graded psychological stress (P<0.05)
|
Disorders |
Group 1 N (%) |
Group 2 N (%) |
Group 3 N (%) |
Group 4 N (%) |
Chi-squared or Exact Fisher’s tests |
P-value |
|
Preterm delivery |
4 (1.1) |
3 (0.8) |
3 (0.8) |
5 (1.4) |
- |
0.24 |
|
Placental abruption |
0 |
0 |
0 |
2 (0.5) |
- |
0.25 |
|
Spontaneous abortion |
12 (3.4) |
5 (1.4) |
6 (1.7) |
10 (2.8) |
7.38 |
0.06 |
|
Fetal defect |
3 (0.8) |
0 |
2 (0.5) |
3 (0.8) |
- |
0.24 |
|
Low birth weight |
6 (1.7) |
3 (0.8) |
4 (1.1) |
5 (1.4) |
2.57 |
0.30 |
|
Premature rupture of membrane |
3 (0.8) |
2 (0.5) |
2 (0.5) |
3 (0.8) |
- |
0.67 |
Table 3. The relative risks of reproductive disorders in the four groups with graded psychological stress (P<0.05)
|
Disorders |
Group 1 RR (CI) |
Group 2 RR (CI) |
Group 3 RR (CI) |
Group 4* RR (CI) |
|
Preterm delivery |
0.32 (0.06-1.64) |
0.48 (0.05-3.03) |
0.49 (0.18-3.10) |
3.92 (0.77-19.81) |
|
Placental abruption |
- |
- |
- |
4.86 (4.01-5.90) |
|
Spontaneous abortion |
0.337 (0.14-0.79) |
2.66 (0.56-12.59) |
0.49 (0.13-1.77) |
2.63 (1.09-6.31) |
|
Fetal defect |
0.32 (0.06-1.64) |
0.34 (0.06-1.54) |
0.49 (0.08-3.00) |
3.92 (0.77-19.81) |
|
Low birth weight |
0.49 (0.13-1.77) |
0.33 (0.05-1.65) |
0.34 (0.16-1.54) |
2.62 (0.72-9.52) |
|
Premature rupture of membrane |
0.49 (0.08-3.00) |
0.35 (0.07-1.64) |
0.47 (0.07-3.00) |
2.58 (0.42-15.72) |
* Group 4 in contrast with the other groups
Discussion
According to the results, group +4 with very severe psychological stress had the highest risk of disorders such as spontaneous abortion and placental abruption and the lowest age. The frequency of some disorders such as spontaneous abortion and low birth weight was the highest in group +1 with mild psychological stress, but the mean age in group +1 was 34.06±3.96, suggesting that the reproductive disorders in this group might be due to aging effect, this group had the longest working hours, as well.
After eliminating age effect, the actual risk of psychological stress was prominent. The results of this study are in line with the other studies investigating the effect of psychological stress on reproductive system (4-7).
This study shows the effects of stress on pregnancy outcome (12, 13), spontaneous abortions, placental abruption and menorrhagia (2). It was found that the risk of disorders was the highest in stressful work situations, especially in shift works. (25, 26). This risk can be modified through psychologist consultation in stressful situations and workplaces. The non-occupational risk factors for reproductive system, which are important factors in workers’ future health, must be questioned before starting a job (2, 29).
All of the reproductive disorders such as spontaneous abortion, fetal defects, low birth weight, placental abruption, premature rupture of membrane (PROM), preterm delivery and menorrhagia, were studied for other etiologies prior to beginning the study. All the work place risks were in permissible exposure levels, except for psychological stress which was different in various work settings. The participants of this study were from different workplaces with different types of psychological stresses. However, irrespective of the work setting, physicians can help with prevention, screening, treatment and rehabilitation of reproductive disorders.
Paying attention to stressful situations at home is important too, which should be asked about by psychologists from the people with stress disorders. Moreover, age of pregnancy is an important risk factor for obstetric disorders, as well. But the women with stressful jobs are at high risk of disorders such as placental abruption and spontaneous abortion of the fetus; therefore, they must be screened for reproductive system health.
Limitations of our study include: not having an exact job analysis and these data were gathered from personnel's memory and health issues. Unfortunately, the sample size after implementing the exclusion criteria became small. It seems that further studies with exact job analysis will be helpful.
Conclusion
This study shows that very severe stress causes high risk of spontaneous abortion and placental abruption. Thus, stress management techniques should be applied for decreasing the risk of obstetric disorders.
Acknowledgements
I wish to thank Mashhad University of Medical Sciences for all the support 900042.
)