Outcomes
Primary outcome of this study was the recurrent risk rate of PTB before 37 weeks of gestation. Secondary outcomes included the recurrent risk of PTB < 24 and PTB <32 weeks. The recurrent risks are reported for the total group as well as subdivided into prior sPTB between 16+0-19+6, 20+0-23+6 and 24+0-27+6 weeks of gestation.