ArticleA descriptive study of asthma in young adults conceived by IVF
Introduction
Infertility is an important public health issue affecting the lives of many couples in the USA and worldwide. Since 1978, over a million infants have been born to infertile couples as a result of assisted reproduction technology (Klonoff-Cohen, 2005). IVF is a special type of treatment whereby both oocytes and spermatozoa are handled and fertilization occurs in an artificial environment outside of the reproductive system. Multiple steps are taken in an IVF treatment cycle; these include ovarian stimulation, oocyte retrieval, fertilization in a liquid medium, embryo selection and embryo transfer into the uterine environment. Scientific evidence remains inconclusive as to whether assisted reproduction is linked to adverse short-term and long-term health effects. Most couples who undergo treatment have pre-existing health problems associated with infertility, and the procedure itself can enhance the risk of birth plurality, which in turn has been linked with preterm delivery and low birthweight infants. While ample evidence linking assisted reproduction technology to preterm deliveries and low birthweight infants exists even in the context of single live births (McDonald et al., 2009), it is unclear whether these birth outcomes are due to parental sub-fertility or characteristics of the procedure itself.
Because assisted reproduction technology is a relatively recent treatment modality for infertility, few studies have evaluated its health effects beyond infancy, childhood and adolescence. Health outcomes that have been evaluated in relation to assisted reproduction technology can be broadly classified as obstetric, perinatal, neonatal, post-neonatal outcomes, chromosomal aberrations, congenital malformations, growth and metabolic disorders and motor, neurological, cognitive and socio-emotional development.
To date, few studies have examined assisted reproduction technology as a putative risk factor for asthma. Asthma is a highly prevalent condition often diagnosed prior to adulthood. Its multi-factorial aetiology has been described elsewhere (Hill and Wood, 2009, Subbarao et al., 2009). In the USA, about 23 million are afflicted with asthma, 6.8 million of whom are children and over half (12 million) have experienced an asthma attack within the last 12 months (NIH, 2009). Preterm delivery and low birthweight have been identified as key risk factors for asthma in a number of studies (Alper et al., 2006, Annesi-Maesano et al., 2001, Linneberg et al., 2006, Metsala et al., 2008, Priftis et al., 2007). The significant relationship between preterm delivery and asthma has been recently established in a meta-analysis of 19 studies (Jaakkola et al., 2006). Because assisted reproduction technology is associated with birth plurality and preterm delivery, it is reasonable to postulate that assisted reproduction technology and asthma may be associated.
The purpose of this descriptive study is to characterize asthma and its associated health outcomes among IVF-conceived young adults. First, the study compared the asthma profile of an IVF population to that of the general population of the USA, using the 2008 Behavioural Risk Factor Surveillance System (BRFSS) as a reference. Second, it examined whether birth plurality and low birthweight played a role in asthma prevalence and associated health outcomes. Given the established link between asthma, preterm delivery and low birthweight, the study postulated that the prevalence of asthma would be increased among IVF-conceived young adults, particularly those who were low birthweight infants or individuals of a multiple gestation. This study was based on a larger cross-sectional survey of young adults (aged 18–26 years) conceived by standard IVF between 1981 and 1990 at a major fertility treatment centre (Beydoun et al., in press).
Section snippets
Study design and setting
This study conducted a cross-sectional evaluation of the first cohort of young adults conceived by IVF at the Jones Institute for Reproductive Medicine (JIRM), the Division of Reproductive Endocrinology and Infertility at Eastern Virginia Medical School (EVMS) in Norfolk, Virginia. The Institutional Review Board at EVMS approved the study with a waiver of informed consent.
Sampling and eligibility
Young adults conceived by standard, or conventional, IVF were recruited and enrolled into the study through their parents.
Results
Demographic, socioeconomic and lifestyle characteristics of the 157 survey respondents are displayed in Table 1. Over half were between 21 and 24 years of age and 55.4% were female. Almost all respondents were white non-Hispanic and nearly three-quarters had achieved a college education or better. In addition, 10.5% of survey respondents were obese and 12.8% reported themselves as current smokers at the time of survey administration. Nearly 24% of respondents were low birthweight and over 39%
Discussion
The link between assisted reproduction technology and chronic disease development through birth plurality and its associated adverse outcomes is biologically plausible but has not yet been fully explored. The fetal origins (Barker, 1991) hypothesis states that fetal undernutrition in middle to late gestation can lead to disproportionate fetal growth, thereby affecting the risk of coronary heart disease later in life. Intrauterine stress to the fetus can also retard growth and constrain lung
Acknowledgements
The authors are indebted to Mrs Nancy Garcia for assistance with mailings and collection of information.
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Mr Nicholas Sicignano received his Master of Public Health degree, epidemiology track, from the graduate programme in public health at Eastern Virginia Medical School in 2009. He completed a Bachelor of Science degree in the area of health sciences with a Minor in public health from James Madison University in 2003. This manuscript is based on his practicum work in collaboration with the Jones Institute for Reproductive Medicine. Upon graduating, Mr Sicignano was hired as a researcher by Battelle Memorial Institute and has been contracted to work as a clinical epidemiologist at the Navy and Marine Corps Public Health Centre in Portsmouth, Virginia.
Author contributions: NS participated in questionnaire design, data management, data analysis and drafted the manuscript. HAB conceived the study, performed data analysis and manuscript write-up. SO, HJ and HR were involved in study design and approval, provided data access and revised the paper for intellectual content.