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Journal of Clinical Gynecology & Obstetrics

Original Article

Volume 5, Number 3, September 2016, pages 81-84

The Effect of Season on the Prevalence of Preeclampsia

Preeclampsia can be defined as a pregnancy-specific syndrome in which a group of clinical symptoms occur simultaneously with unclear etiologies. Decreased perfusion secondary to vascular spasm, endothelial dysfunction and ischemia are among possible factors affecting preeclampsia. This complication appeared in early pregnancy and the pathophysiological changes begin from the moment of conception [1, 2]. Its clinical symptoms are hypertension and proteinuria during the second half of pregnancy because the chief target organ is the kidney (glomerular endotheliosis) [3, 4]. This complication affects 5-10% of all pregnancies and also 20% of first pregnancies and involves more than 40% of premature birth resulting from treatment [5].

The incidence of preeclampsia is affected by various factors including parity, African American race, ethnicity, genetics, age over 35 years, and systemic diseases (hypertension, diabetes, chronic kidney disease, and endocrine disorders) [1, 2]. There are also many environmental factors such as living at high altitudes, obesity, and multiple births [6]. Based on recent studies, there is the probability of a significant relationship between the incidence of preeclampsia and eclampsia with the change of seasons [7-12].

Majority of published studies indicate increased incidence of preeclampsia in cold and wet seasons of the year. Since the pathophysiology of preeclampsia is vasoconstriction, the increasing incidence in cold and wet seasons could be due to the effect of temperature and humidity on vasoconstriction and secretion of vasoactive substances. On the other hand, dry and rainy seasons may be effective on the type of infection that affects the mother during pregnancy and consequently be involved in the pathophysiology of preeclampsia [7, 8, 12].

Considering that preeclampsia is a major complication of pregnancy and also one of the three main causes of maternal mortality and so far this has not been studied in Kurdistan Province, Iran, this study aimed to determine the effect of season on the prevalence of preeclampsia in pregnant women referring to Sanandaj Besat Hospital during 2013 - 2014.

Sanandaj City, Kurdistan Province, Iran, is located on the geographic coordinates of 35°20' north latitude and 47°18' east longitude of the prime meridian. Height average of Sanandaj is 1,535 m above sea level (the lowest and highest points are 600 and 2,550 m, respectively). The city has a semi-arid Mediterranean climate.

This descriptive study was conducted on 363 pregnant women referring to Sanandaj Besat Hospital during 2013 - 2014. The data were collected using a questionnaire with three parts. The first part included demographic information, the second part included information on the underlying disease, such as diabetes, hypertension, endocrine disorders, kidney disease, connective tissue disease, and infertility history, and the third part included information on pregnancy, such as use or non-use of assisted reproductive techniques, singleton or multiple pregnancy, gravidity, history of gestational diabetes, history of gestational hypertension, infectious disease during pregnancy, months and seasons of conception, and months and seasons of incidence of preeclampsia. Data were obtained from medical records of pregnant women who were hospitalized because of preeclampsia and analyzed with STATA-11 and Chi-square test.

The results showed that the mean age of women diagnosed with preeclampsia was 30.5 ± 6.60 years. A total of 209 (57.6 %) women were living in urban and 154 (42.4%) in rural areas, 35% were high school graduates, and 41.9% were primigravida. The prevalence of preeclampsia in urban and rural pregnant women was 10% and 4%, respectively. The incidence of preeclampsia was 30% during the winter months (Table 1).

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Table 1. Demographic Characteristics of the Pregnant Women

The mean systolic and diastolic blood pressures were 143.2 ± 15.5 and 86.2 ± 12.2 mg/dL, respectively. A total of 22.3% had history of gestational diabetes, 16.3% had history of preeclampsia and 10.5% had history of hypertension (Table 2).

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Table 2. History of Disease in Pregnant Women

There was no statistically significant relationship between the season of conception and the month of preeclampsia in pregnant women (P = 0.67) (Table 3).

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Table 3. The Relationship Between Season of Conception and the Month of Preeclampsia in Pregnant Women (P = 0.67)

In this study, the mean age of women when diagnosed with preeclampsia was 30.5 ± 6.6 years. It was 28.61 ± 6.00 and 28 ± 5.7 years, respectively in Shahidifar et al [13] and Ghanbari Homayi study [14]. The results showed that the highest incidence of preeclampsia (67.8%) was in the age group 20 - 35 years. In a study by Kahnamouei-Aghdam et al, 42.4% of women had preeclampsia and the highest incidence of preeclampsia was for the age group 25 - 30 years [15] which is consistent with our study.

The results of this study showed that preeclampsia was the most prevalent in winter. In a study by Magnus and Eskild, the highest incidence of preeclampsia was reported in winter [8]. Khojasteh et al have reported the highest incidence of preeclampsia in fall [7]. Shahidifar et al have also reported the highest incidence of preeclampsia in autumn and winter [13]. In a study by Okafor and Ezegwui, the incidence of preeclampsia was higher in wet seasons [9]. The highest incidence of preeclampsia has been reported in spring and lowest in summer by Zahiri Soroori et al [12]. The results of a study by Wellington and Mulla showed that most cases of preeclampsia were in winter [16]. Shental et al also showed that winter has a higher prevalence of preeclampsia [17]. The results of the majority of cited studies were consistent with the present study. However, understanding the relationship between climate patterns and preeclampsia can be useful to determine the risk factors of preeclampsia [18].

It seems that temperature changes plasma volume due to changes in the weather, therefore it has been proposed as mechanism for explaining the seasonal variation in the frequency of preeclampsia [16]. It has been assumed that cold weather could lead to vasospasm that develops a portion of the pathogenesis of preeclampsia [8].

Based on the results of this study, the highest incidence of preeclampsia was associated with conception in the spring. Philips et al concluded that the risks of preeclampsia appear higher for women with conception during the warmest months, and delivery in the coldest months of the year [11]. In a study by Beltran et al, the highest incidence of preeclampsia was associated with conception in the summer months [19]. Mohaddesi and Nanbakhsh showed that preeclampsia incidence increased in cases of conception in warm seasons particularly in summer [20]. These studies are not in consistent with our study.

In this study, there was no statistically significant relationship between the seasons of conception and the month of preeclampsia. This finding is not in consistent with the study by Ghanbari Homayi et al which found a significant association between preeclampsia and season of conception [14].

In the present study, 41.9% of subjects were primigravida. In a study by Sarwar et al primigravida pregnant women were at higher risk for the development of preeclampsia than the multigravida pregnant women [21]. Sharemi et al also concluded that multiparity had a preventive effect on mild and severe types of preeclampsia [22]. These studies are in consistent with our study.

According to the descriptive results of this study, the incidence of preeclampsia is higher in urban than rural population which is consistent with van Middendorp et al study [23] and is not consistent with the results of study by Sarwar et al [21].

Based on the findings of this study, it can be said that the incidence of preeclampsia is higher in winter than in summer and also its incidence is lower in urban multiparous women.

Acknowledgments

Authors would like to thank Faculty of Medicine of Kurdistan University of Medical Sciences to support this study financially. This article has been taken from thesis of general practitioner course.

1. Cunningham FG. Williams obstetrics. 24th edition. New York: McGraw Hill; 2014.
2. Danforth D, Scott J. Danforth's obstetrics and gynecology. 10th edition. Philadelphia: Lippincott Williams & Wilkins; 2008.
3. ACOG practice bulletin. Diagnosis and management of preeclampsia and eclampsia. Number 33, January 2002. Obstet Gynecol. 2002;99(1):159-167.
   pubmed
4. Hladunewich M, Karumanchi SA, Lafayette R. Pathophysiology of the clinical manifestations of preeclampsia. Clin J Am Soc Nephrol. 2007;2(3):543-549.
   doi pubmed
5. Lawler J, Osman M, Shelton JA, Yeh J. Population-based analysis of hypertensive disorders in pregnancy. Hypertens Pregnancy. 2007;26(1):67-76.
   doi pubmed
6. Kashanian M, AliMohammadi R, Baradaran HR. Evaluation of Some of the Risk Factors for Preeclampsia. RJMS. 2008;15(59):131-136.
7. Khojasteh F, Safarzadeh A, Borayri T, Baghban K. Survey correlation between preeclampsia and season and some of its risk factor in pregnant women. Journal of shahrekord university of medical sciences. 2011;13(1):79-84.
8. Magnus P, Eskild A. Seasonal variation in the occurrence of pre-eclampsia. BJOG. 2001;108(11):1116-1119.
   doi
9. Okafor UV, Ezegwui HU. Cesarean delivery in preeclampsia and seasonal variation in a tropical rainforest belt. J Postgrad Med. 2010;56(1):21-23.
   doi pubmed
10. Vidya Subramaniam. Seosonal variation in the incidence of preeclampsia and eclampsia in tropical condition's. JBMC. 2007:64(4):125-129.
11. Phillips JK, Bernstein IM, Mongeon JA, Badger GJ. Seasonal variation in preeclampsia based on timing of conception. Obstet Gynecol. 2004;104(5 Pt 1):1015-1020.
    doi pubmed
12. Zahiri soroori Z, Sharami SH, Faraji R. Seosonal variation of the onset of preeclampsia and eclampsia. Journal of research in medical sciences. 2007;12(4):198-202.
13. Shahidifar S, Sharifnia H, Taghipoor B, Hekmat Afshar M, Motevalli R, khalili Y, Mazraie F. Association between seasonal patterns and preeclampsia. The Iranian Journal of Obstetrics and Gynecology and Infertility. 2014;17(25):8-14.
14. Ghanbari Homayi S, Malakouti J, Asghari M, Farshbaf Khalili A, Ghahremani Nasab P. Relationship between Season of Conception, Birth and Other Predictors in Women with Eclampsia Referring to Alzahraa and Taleghani Hospitals in Tabriz, Iran, 2007-2012. The Iranian Journal of Obstetrics and Gynecology and Infertility; 2013;16(75):22-29.
15. Kahnamouei-aghdam F, Amani F, Hamidimoghaddam S. Prevalence of pre-eclampsia and eclampsia risk factors among pregnant women, 2011-2013. Int J Adv Med. 2015;2(2):128.
    doi
16. Wellington K, Mulla ZD. Seasonal trend in the occurrence of preeclampsia and eclampsia in Texas. Am J Hypertens. 2012;25(1):115-119.
    doi pubmed
17. Shental O, Friger M, Sheiner E. Ethnic differences in the monthly variation of preeclampsia among Bedouin and Jewish parturients in the Negev. Hypertens Pregnancy. 2010;29(3):342-349.
    doi pubmed
18. Shahidi Far S, Taghipour B, Sheikhnejad F, Allahyari Z. Preeclampsia and Seasonal Changes Patterns: A cross Sectional Study. J Appl Environ Biol Sci. 2015;5(4):161-165.
19. Beltran AJ, Wu J, Laurent O. Associations of meteorology with adverse pregnancy outcomes: a systematic review of preeclampsia, preterm birth and birth weight. Int J Environ Res Public Health. 2014;11(1):91-172.
    doi pubmed
20. Mohaddesi H, Nanbakhsh F. Seasonal Variation in the Incidence of Preeclampsia Based on the time of conception. World Applied Sciences Journal. 2013;28(12):2242-2248.
21. Sarwar MS, Sarkar RC, Bhowmick R, Dewan SM, Ahmed MU, Hasnat A, Rashid M, et al. Effect of socio-economic status and estimation of lipid peroxidation and antioxidant in preeclamptic pregnant women: a case-control study. Hypertens Pregnancy. 2015;34(1):125-135.
    doi pubmed
22. Sharemi SH, Milani F, Zahiri Z, Zendedel M, Salamat F, Rafipour B, Javid Z. Comparison of Pre-Eclampsia Risk Factors Regarding to Its Severity in Pregnant Women Referred to Alzahra Hospital of Rasht, Iran, 2012. The Iranian Journal of Obstetrics and Gynecology and Infertility. 2012;16(69):1-8.
23. van Middendorp D, ten Asbroek A, Bio FY, Edusei A, Meijjer L, Newton S, Agyemang C. Rural and urban differences in blood pressure and pregnancy-induced hypertension among pregnant women in Ghana. Global Health. 2013;9:59.
    doi pubmed

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