Fig 1.
Parturition begins weeks before labour onset.
(A) Labour is an inflammatory process with elevated levels of maternal circulating leukocytes and increased leukocyte infiltration into the myometrium, decidua and cervix before and during labour. (B) Parturition is a long complex process that begins weeks before the onset of labour. The cervix gradually ripens and the myometrium switches from a quiescent to a contractile state. (C) In preterm birth, the cascade of events culminating in birth is transposed earlier in gestation. iNOS, induced nitric oxide synthase; IL8, interleukin 8; HA, hyaluronan; GAGs, glycosaminoglycans; T1, study samples collected at 17–23 weeks of gestation; T2, study samples collected at 27–33 weeks of gestation. Illustrations adapted from Word et al [18].
Fig 2.
Flowchart outlining the recruitment, patient phenotyping and sample selection process for this study.
Table 1.
Demographic, clinical, labour and delivery characteristics of the 165 participants.
Table 2.
Multivariate models (Models A, B and C) associated with spontaneous preterm birth (SPTB) at 17–23 (T1) and 27–33 (T2) weeks of gestation.
Fig 3.
The area under receiver operator characteristic curves of Models A, B and C after ten five-fold cross-validation (CV) runs. These three multivariate models were constructed to identify gene expression associated with spontaneous preterm birth (SPTB) at 17–23 weeks (A; Model A) and 27–33 weeks (B; Model B); and gene expression fold change from 17–23 to 27–33 weeks of gestation associated with SPTB (C; Model C). Models with clinical factors are represented using solid lines; Models without clinical factors are represented using dotted lines. The rainbow bar on the right of each plot displays cut-off probabilities. The colour of the points along the average CV curve reflects its respective cut-off probability to obtain the desired sensitivity and specificity.