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Temporal trends in gestational-age specific preterm birth rates following PPROM, spontaneous labour and clinician-initiated delivery; at 24–27 weeks (Panel A), 28–31 weeks (Panel B), 32–33 weeks (Panel C) and 34–36 weeks (Panel D); Washington State, USA, 2004–2013. PPROM, preterm premature rupture of membranes.
