Objective Our aim was to examine the association between biological determinants of preterm birth (infection and inflammation, placental ischaemia and other hypoxia, diabetes mellitus, other) and spontaneous late preterm (34-36 weeks) and early term (37-38 weeks) birth.Design Retrospective cohort study.Setting City of London and Middlesex County, Canada.Sample Singleton live births, delivered at 34-41 weeks to LondonMiddlesex mothers following spontaneous labour.Methods Data were obtained from a city-wide perinatal database on births between 2002 and 2011 (n = 17 678). Multivariable analyses used multinomial logistic regression.Main outcome measure The outcome of interest was the occurrence of late preterm (34-36 weeks) and early term (37-38 weeks) birth, compared with full term birth (39-41 weeks).Results After controlling for covariates, there were associations between infection and inflammation and late preterm birth (aOR = 2.07, 95% CI 1.65, 2.60); between placental ischaemia and other hypoxia and late preterm (aOR = 2.21, 95% CI 1.88, 2.61) and early term (aOR = 1.25, 95% CI 1.13, 1.39) birth; between diabetes mellitus and late preterm (aOR = 3.89, 95% CI 2.90, 5.21) and early term (aOR = 2.66, 95% CI 2.19, 3.23) birth; and between other biological determinants (polyhydramnios, oligohydramnios) and late preterm (aOR = 2.81, 95% CI 1.70, 4.64) and early term (aOR = 1.89, 95% CI 1.32, 2.70) birth.Conclusions Our findings show that delivery following spontaneous labour even close to full term may be a result of pathological processes. Because these biological determinants of preterm birth contribute to an adverse intrauterine environment, they have important implications for fetal and neonatal health.
Objective Our objectives were: (1) to examine the association between maternal, fetal, and placental phenotypes of preterm delivery and medically indicated early delivery of singletons during the late preterm and early term periods; and (2) to identify the specific maternal, fetal, and placental conditions associated with these early deliveries.Design Retrospective study.Setting City of London and Middlesex County, Ontario, Canada.Sample Singleton live deliveries, at 34-41 weeks of gestation to women in London and Middlesex.Methods We obtained data from a city-wide perinatal database (2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011); n = 25 699). We used multinomial logistic regression for multivariable analyses.Main outcome measure The outcome was the occurrence of medically indicated late preterm (34-36 weeks of gestation) and early term (37-38 weeks of gestation) delivery, versus delivery at full term (39-41 weeks of gestation).Results After controlling for confounding factors, all phenotypes were associated with increased odds of medically indicated late preterm and early term delivery. Within the maternal phenotype, chronic maternal medical conditions were associated with increased odds of medically indicated early term delivery (e.g. for gastrointestinal disease, adjusted odds ratio, aOR 1.72, 95% CI 1.47-2.00; for anaemia, aOR 1.40, 95% CI 1.20-1.63), but not late preterm delivery.Conclusions The aetiology of medically indicated early delivery close to full term is heterogeneous. Patterns of associations suggest slightly different conditions underlying the late preterm and early term phenotypes, with chronic maternal medical conditions being associated with early term delivery but not with late preterm delivery. These results have implications for the prevention of early delivery as well as the identification of high-risk groups among those born early.Keywords Chronic disease, pregnancy complications, preterm birth, term birth.Tweetable Abstract The aetiology of medically indicated late preterm and early term delivery is heterogeneous.
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