Abstract
Household crowding can place young children at risk for respiratory infections which subsequently provoke asthma symptoms. However, crowding might also protect against asthma, in accordance with the hygiene hypothesis. We tested if parent–infant bed-sharing, an important dimension of household crowding, increases or decreases the risk for asthma.
In a population-based prospective cohort (N = 6160) we assessed bed-sharing at 2 and 24 months; wheezing between 1 and 6 years of age; and asthma at 6 years of age. Generalised estimating equation models were used to assess repeated measures of wheezing and asthma.
We found no association between bed-sharing in early infancy and wheezing or diagnosis of asthma. By contrast, we found a positive association between bed-sharing in toddlerhood and both wheezing (OR 1.42, 95% CI 1.15–1.74) and asthma (OR 1.57, 95% CI 1.03–2.38). Wheezing was not associated with bed-sharing when using cross-lagged modelling.
This study suggests that bed-sharing in toddlerhood is associated with an increased risk of asthma at later ages, and not vice versa. Further studies are needed to explore the underlying causal mechanisms.
Abstract
More wheezing and asthma reported for bed-sharing toddlers, not for infants: parental vigilance or increased risk? http://ow.ly/Dgy4v
Footnotes
For editorial comments see Eur Respir J 2015; 45: 596–600 [DOI: 10.1183/09031936.00234814].
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Support statement: The general design of the Generation R Study was made possible by financial support from the Erasmus Medical Center, Rotterdam, the Erasmus University Rotterdam and the Netherlands Organization for Health Research and Development. The present study was supported by additional grants from the Netherlands Organization for Scientific Research: grant number 017.106.370 (NWO ZonMW VIDI) to H. Tiemeier, and the NWO SPINOZA prize to M.H. van IJzendoorn. A. Sonnenschein-van der Voort is the recipient of a European Respiratory Society Fellowship (STRTF 93-2012) and received a grant from the Ter Meulen Fund, Royal Netherlands Academy of Arts and Sciences (TMF2012/228).V. Jaddoe received an additional grant from the Netherlands Organization for Health Research and Development (ZonMw-VIDI). L. Duijts received funding from a European Respiratory Society/Marie Curie Joint Research Fellowship (number: MC 1226-2009, grant agreement: RESPIRE, PCOFUND-GA-2008-229571), and the Lung Foundation Netherlands (number: 3.2.12.089; 2012). None of the authors had a financial or personal conflict of interest related to the content of the study.
Conflict of interest: Disclosures can be found alongside the online version of this article at erj.ersjournals.com
- Received March 3, 2014.
- Accepted October 10, 2014.
- Copyright ©ERS 2015