Flow chart of the proposed method.
Note: PE: preterm delivery with EHG recorded before the 26th gestation week, TE: term delivery with EHG recorded before the 26th gestation week, PL: preterm delivery with EHG recorded after the 26th gestation week, TL: term delivery with EHG recorded after the 26th gestation week, ADASYN: adaptive synthetic sampling approach, AUC: the area under the curve of receiver operating characteristic.