The impact of parity and age at first and last childbirth on the prevalence of delayed-onset asthma in women: The Korean National Health and Nutrition Examination Survey
Introduction
Asthma is an inflammatory disorder of the airway and lung tissue that varies in nature and severity over time. A core feature of asthma is the presence of airway hyper-responsiveness, a condition in which individuals respond to non-allergic stimuli (e.g., cigarette smoke and fog) with airway obstruction, wheezing, and other respiratory symptoms that do not occur in healthy individuals [1]. There has been a sharp increase in the global prevalence, morbidity, mortality, and economic burden associated with asthma over the past 40 years. Many epidemiologic studies suggest the presence of gender differences in asthma prevalence and severity vary according to age. The prevalence of asthma is higher among males during childhood, approximately equal in both sexes during teenage years, and higher among females during adulthood [2]. Although, large epidemiologic studies investigating menopause and asthma are scarce and show contradictory results [3], recent several studies pointed to a higher asthma prevalence in post-menopause [4], [5]. Furthermore, the number of respiratory symptoms was higher in women who were postmenopausal at follow-up [6]. In addition, asthma severity has been found to vary during the menstrual cycle and pregnancy. These findings suggest that reproductive hormones influence the development of asthma and asthma severity [7].
There have been several studies which aimed to verify the association between reproductive factors, particularly hormone exposure, and the prevalence or severity of asthma among women. However, the associations between these factors remain controversial. Women with early menarche and pregnancy have higher estrogen levels and are exposed to greater cumulative estrogen and progesterone concentrations [7]. One study reported that bronchial hyper-responsiveness, a key feature of asthma, was significantly associated with early menarche [8]. Another study found that early menarche, before 11 years of age, was not associated with an increased risk of wheezing during adolescence [9]. Similarly, Jenkins et al. reported that the risk of later-onset asthma among women with no asthma by age seven was associated with increased parity [2], but others found that women with greater numbers of intervening pregnancies were more likely to have lost their atopic status and did not observe any relationship between pregnancy and current symptoms of asthma [10], [11]. Nevertheless, these data on the pattern of asthma according to sex hormonal status has been limited to local communities or particular age groups; population-based studies on the relationship between asthma and these factors are lacking. It is important to recognize the factors associated with asthma and its etiology in order to prevent possible complications. The aim of this study was to analyze the prevalence of asthma and its potential risk factors, including menarche, parity, and timing of first or last pregnancy using KNHANES data, a government-driven survey of the Korea Center for Disease Control and Prevention.
Section snippets
Study population
This study was based on data collected during the 2010–2012 KNHANES (Korea Centers for Disease Control and Prevention). KNHANES has been conducted by the Division of Chronic Disease Surveillance under the Korea Centers for Disease Control and Prevention since 1998. It is a nationwide survey designed to assess national health and nutrition levels accurately. The survey consists of a health interview, a nutritional survey, and a health examination. Trained staff carried out standard physical
General characteristics of the study population
Among the 7837 women ≥ 19 years of age, 243 had experienced asthma; the prevalence of asthma was 3.10% (95% confidence interval: 2.73–3.51%). The baseline characteristics of the study subjects according to asthma are shown in Table 1. The mean age of those with asthma was significantly higher than those without asthma. BMI, history of hypertension, income level, education level, occupation, alcohol consumption, age at menarche and first birth, and parity were significantly associated with asthma.
Prevalence of asthma with respect to age at first and last birth and parity
Discussion
Asthma is one of the most common chronic respiratory diseases, and the prevalence of asthma in adults ranges from 1.8% in Vietnam to 32.8% in Australia [15]. These findings have been explained by the possibility that environmental factors related to living conditions in these countries may be important [16]. In the present study, the prevalence of asthma in Korean adults women aged over 19 years was 3.1%, and that was relatively low compared to other countries (3.9% in 2006 in Japan; ranged
Conclusions
After controlling for confounders, among various risk factors, the age at first childbirth of <20 was significantly associated with the prevalence of delayed onset-asthma among Korean women. Although the statistical significance disappeared after adjustment, higher parity continuously showed a tendency toward correlation with the prevalence of delayed onset-asthma in women. Additional studies are needed to understand the complex relationships between asthma, parity and age at first and last
Conflict of interest
The authors declare no conflict of interest.
Funding
This work was supported by the National Research Foundation of Korea Grant funded by the Korean Government (NRF-2016R1C1B2015652). The study was supported by the Soonchunhyang University Research Fund. However, these funding sources had no involvement in the study design, collection, analysis and interpretation of data, or writing of the report.
Ethical approval
Approval for this study was obtained from the Institutional Review Board of the Catholic University of Korea in Bucheon, Korea. Written informed consent was obtained from all participants prior to the survey.
Provenance and peer review
This article has undergone peer review.
Acknowledgments
We thank the staffs and members of the Division of Chronic Disease Surveillance in Korea Centers for Disease Control & Prevention for participating in this survey and the dedicated work they provided.
References (22)
- et al.
Asthma and the menopause: a systematic review and meta-analysis
Maturitas
(2012) - et al.
Dietary carbohydrate intake is associated with cardiovascular disease risk in Korean: analysis of the third Korea National Health and Nutrition Examination Survey (KNHANES III)
Int. J. Cardiol.
(2010) - et al.
Role of gender and hormone-related events on IgE, atopy, and eosinophils in the Epidemiological Study on the Genetics and Environment of Asthma bronchial hyperresponsiveness and atopy
J. Allergy. Clin. Immunol.
(2004) - et al.
Asthma and asthma-like symptoms in adults assessed by questionnaires. A literature review
Chest
(1993) Gender differences in asthma development and progression
Gend Med.
(2007)- et al.
Parity and decreased use of oral contraceptives as predictors of asthma in young women
Clin. Exp. Allergy
(2006) - et al.
Lung function, respiratory symptoms, and the menopausal transition
J. Allergy Clin. Immunol.
(2008) - et al.
Hormone replacement therapy, body mass index and asthma in perimenopausal women: a cross sectional survey
Thorax
(2006) - et al.
Menopause as a predictor of new-onset asthma: a longitudinal Northern European population study
The J. Allergy Clin. Immunol.
(2016) - et al.
Parity, age at first birth, and risk of death from asthma: evidence from a cohort in taiwan
Int. J. Environ. Res. Public Health
(2014)
Association between menarche and increased bronchial hyper-responsiveness during puberty in female children and adolescents
Pediatr. Pulmonol.
Cited by (10)
Effect of women’s fertility and sexual development on epigenetic clock: Mendelian randomization study
2023, Clinical EpigeneticsAssociations Between Reproductive Factors and the Risk of Adult-Onset Asthma: A Prospective Cohort Study of European Ancestry
2023, Journal of General Internal MedicineAssociation between selected urinary heavy metals and asthma in adults: a retrospective cross-sectional study of the US National Health and Nutrition Examination Survey
2021, Environmental Science and Pollution Research