The association between maternal country of birth and neonatal intensive care unit outcomes
Introduction
According to the International Organization for Migration, the number of international migrants is expected to increase from 214 million in 2010 to 405 million by 2050 [1]. Countries that were once ethnically homogeneous may be beset with vastly different health problems due to genetic [2], cultural [3] and assimilation [4] issues.
An “immigrant paradox” has been recognized since the 1960s [5] where arrivals from poorer socio-economic regions were noted to be healthier than the original inhabitants of the new country, even when ethnic differences were taken into account [6]. This counter-intuitive phenomenon (as marginalized and impoverished people usually have consistently poorer outcomes) [7], [8] may be explained by a selective process, as usually only the fittest and healthiest people have the opportunity to migrate. On the other hand, what is more difficult to explain is the predisposition of more affluent backgrounds, e.g. Asian Indians migrating to the United States for employment, to a higher risk of health problems despite optimum health care [9].
The effect of these phenomena on neonatal intensive care unit (NICU) outcomes has not been explored. In this field, time-critical decisions are often based on data extracted by an often ethnically-homogenous native population [10], [11] and may not be applicable to children of non-Caucasian and immigrant parents [12]. For example, Asian infants have less severe hyaline membrane disease but worse retinopathy of prematurity [13]. Adhering to standard definitions of certain conditions, e.g. World Health Organization (WHO) criteria for gestational diabetes mellitus (GDM), may result in sub-optimal clinical outcomes e.g. Japanese women need more stringent glycemic control to prevent adverse perinatal complications [14].
Currently, there is no population study of the effects of maternal country of birth on high-risk perinatal outcomes. In this study, we used record linkage to determine this association in the state of New South Wales (NSW), Australia, between 2000 and 2006. Due to the unrestricted nature of Australian health care, we hypothesized that short and long-term outcomes, including survival and rehospitalization after NICU discharge, will not be different between children of native-born and immigrant mothers.
Section snippets
Methods
This was a retrospective record linkage analysis that combined information between an NICU database and that of routinely collected public health data to determine outcomes of infants registered in NICUS in NSW, Australia. Infants were born between January 1st 2000 and December 31st 2006. Linkage was performed between all databases for that time period. Children born in the later years were therefore tracked for a shorter time that those born earlier.
Results
A total of 18,845 children were registered in the NICUS database between 1998 and 2006. After removal of uninformative records, including infants without a PDC record and those born before July 2000 (Fig. 1), the details of 11,979 children and 10,982 mothers were assessed. There were 9813 (81.9%) infants of Australian born mothers and 2166 (18.1%) infants of immigrant mothers (c.f. 167,673 of 605,501 births in NSW between 2000 and 2006, 27.7%, p < 0.001) [18], [20].
Mothers originated from 122
Discussion
Our study is the first to determine the effects of maternal country of birth and ethnicity on NICU outcomes. Even though there were no differences in mortality, other issues were noted that could have significant impact on perinatal management. For example, overseas born Pacific Islander mothers and mothers from low-income regions were significantly more likely to develop GDM and FD than local mothers. These problems were originally noted in Pacific Islanders more than 20 years ago [21] in the
Conflicts of interest
All authors disclose that there is no actual or potential conflict of interest, including financial, personal or other relationships with people or organizations that could inappropriately influence and bias our work.
Acknowledgments
The authors thank the Directors, the NICUS members and the audit officers of all tertiary units in supporting this collaborative study: NICUS, Dr Jennifer Bowen (Chairperson), Barbara Bajuk (Coordinator); Canberra Hospital, A/Prof Zsuzsoka Kecskés (Director), A/Prof Alison Kent, John Edwards; John Hunter Children's Hospital, Dr Chris Wake (Director), Lynne Cruden; Royal Prince Alfred Hospital, A/Prof Nick Evans (Director), Dr Phil Beeby, A/Prof David Osborn, Shelley Reid; Liverpool Hospital, Dr
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