Heterogeneity of respiratory distress syndrome: risk factors and morbidity associated with early and late gestation disease.
BACKGROUND
Although respiratory distress syndrome (RDS) is considered a disease of prematurity, there is evidence to suggest heterogeneity between early and late gestation RDS. We examined the epidemiologic features of RDS occurring at early and late gestation.


METHODS
We conducted a retrospective cohort study including live births in the United States in 2005-06, with information obtained from the National Center for Health Statistics. Early (<32 weeks) and late gestation RDS (≥39 weeks) were contrasted in terms of risk factors and associations with pregnancy complications, obstetric intervention and co-morbidity. Logistic regression was used to quantify the effects of risk factors, while other associations were quantified descriptively.


RESULTS
There were 27,971 RDS cases, yielding an incidence of 6.4 per 1000 live births. Early and late gestation RDS differed in terms of risk factors, with factors such as multi-fetal gestation more strongly associated with early (adjusted odds ratio [aOR] 11.6, 95 % confidence interval 11.0-12.2) compared with late gestation RDS (aOR 3.66, 95 % confidence interval 2.68-4.98). The morbidity correlates of early and late gestation RDS also differed substantially; neonatal seizures were less strongly associated with early (OR 5.90, 95 % confidence interval 3.67-9.47) compared with late gestation RDS (OR 33.1, 95 % confidence interval 27.2-40.2), while meconium aspiration syndrome was not significantly associated with early gestation RDS (OR 1.87, 95 % confidence interval 0.94-3.72) and very strongly associated with late gestation RDS (OR 39.8, 95 % confidence interval 34.7-45.6).


CONCLUSIONS
Differences in risk factors and morbidity correlates of early and late gestation RDS suggest that these entities represent two distinct diseases.
Department of Obstetrics and Gynaecology, University of British Columbia and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver, BC, Canada. azar.mehrabadi@mail.mcgill.ca.|Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Purvis Hall, 1020 Pine Ave. West, Montreal, QC, H3A 1A2, Canada. azar.mehrabadi@mail.mcgill.ca.
Azar
A
Mehrabadi
Department of Obstetrics and Gynaecology, University of British Columbia and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver, BC, Canada.
Sarka
S
Lisonkova
Department of Obstetrics and Gynaecology, University of British Columbia and the Children's and Women's Hospital and Health Centre of British Columbia, Vancouver, BC, Canada.|School of Population and Public Health, University of British Columbia, Vancouver, BC, Canada.
K S
KS
Joseph
Gestational age; Hyaline membrane disease; Preterm; Respiratory distress syndrome; Respiratory morbidity; Risk factors; Term newborns
Am J Epidemiol. 2010 Apr 1;171(7):826-36
20185417
J Pathol. 2006 Jan;208(2):176-86
16362996
N Engl J Med. 1976 Feb 12;294(7):357-60
1246288
J Obstet Gynaecol Can. 2004 Nov;26(11):953-60
15560858
Cancer. 1957 Sep-Oct;10(5):1045-54
13472655
BJOG. 2011 Dec;118(13):1617-29
21895957
Obstet Gynecol. 2007 Apr;109(4):813-22
17400841
BMJ. 2008 Jan 12;336(7635):85-7
18077440
Paediatr Perinat Epidemiol. 2013 Mar;27(2):172-81
23374062
BMJ. 1998 Dec 5;317(7172):1549-53
9836652
Am J Obstet Gynecol. 2001 Sep;185(3):608-13
11568786
J Intern Med. 2008 Dec;264(6):537-48
19017178
Am J Physiol Lung Cell Mol Physiol. 2001 Apr;280(4):L602-5
11237999
Neonatology. 2010 Jun;97(4):402-17
20551710
Placenta. 2011 Jul;32(7):487-92
21531458
J Perinatol. 2005 Apr;25(4):251-7
15605071
Am J Obstet Gynecol. 1990 Jan;162(1):121-5
2301480
Pediatrics. 2004 Aug;114(2):372-6
15286219
Acta Paediatr Scand. 1986 Sep;75(5):832-9
3564950
Pediatrics. 1959 Dec;24:1069-101
14406605
Int J Gynaecol Obstet. 1993 Oct;43(1):35-40
7904952
Cochrane Database Syst Rev. 2012 Nov 14;11:CD001456
23152207
Cancer Res. 1966 Jun;26(6):1189-201
5329907
Am J Obstet Gynecol. 2013 Jul;209(1):29.e1-29.e19
23524176
Acta Paediatr. 1999 Nov;88(11):1244-8
10591427
Obstet Gynecol. 1996 Feb;87(2):163-8
8559516
Pediatrics. 2009 Apr;123(4):e668-72
19336357
J Matern Fetal Med. 2000 Jul-Aug;9(4):224-8
11048833