The effects of housing on the health of preterm infants

Using a prospective study based on cases and controls selected from a geographical population, we have investigated the effects of housing on the health of very preterm infants (less than or equal to 32 weeks' gestation) during the first year of life. Information on health morbidity of the 117 preterm and 226 term babies was collected using a parent-held record, and housing data by a validated self-completion questionnaire. The most common health problems in the first year - upper (UR) and lower (LR) respiratory tract infection, otitis media (OM) and diarrhoea and vomiting (DV) - were all more frequent in the preterm group, There were no significant differences in the housing conditions to which preterm and control infants were exposed. Relative risks (RR) and 95% confidence intervals (CI) associated with each housing factor were calculated for preterm and control infants separately. Significant (P < 0.05) interaction effects were found for overcrowding and gas cooking. Overcrowding was associated with an increased incidence of LR [RR=1.53; CI 0.96-7.42] and DV [RR=1.57; CI 0.92-2.67] in the preterm, but with a decreased incidence of LR [RR = 0.28; CI 0.04-1.86] and DV [RR = 0.85; CI 0.30-2.38] in the term controls. The use of gas ovens was found to be associated in preterm infants with an increase in LR [RR = 1.48; CI 0.96-2.28] and DV [RR=2.24; CI 1.28-3.93] but the controls did not show this effect for LR [RR=0.67; CI 0.40-1.09] or DV [RR=0.93; CI 0.56-1.56]. These associations are robust - even after allowing for confounding social factors - but causality, has not been proved. This work suggests that preterm infants may be vulnerable to specific adverse housing factors, and further studies are now indicated to clarify potential mechanisms and interactive effects behind these associations.