The impact of cervical conization size with subsequent cervical length changes on preterm birth rates in asymptomatic singleton pregnancies

Abstract The study aimed to explore the impact of cervical conization size (CCS) with subsequent cervical length (USCL) changes on preterm birth (PTB) rates in asymptomatic singleton pregnancies as compared to pregnancy outcomes in healthy women with an intact cervix (ICG), and to estimate PTB prevention efficiency in patients with a short cervix. Pregnancy outcomes in populations of similar age, ethnicity, residency, education and harmful habits having undergone cervical conization (CCG) were retrospectively analyzed and compared to ICG and cervical conization sub-populations adjusted by USCL during pregnancy (adequate cervical length vs. a short cervix) and a progesterone-only group (POG) vs. a progesterone-pessary group (PPG). Cervical conization was not associated with an increased PTB risk (CCG vs. ICG) when parameters of CCS and USCL were not adjusted (p = NS). A significantly higher proportion of parous women was observed in the CCG population than in the ICG (p = 0.0019). CCS turned out to be a key PTB risk during pregnancy, the larger CCS being associated with a short cervix (p = 0.0001) and higher PTB risks (p = 0.0001) with a notably increased PTB rate (p = 0.0001) in nulliparous women (p = 0.0022), whereas smaller CCS with adequate cervical length and a lower PTB rate was predominantly observed in women with prior parity. An initial equal USCL size was to be considerably elongated in women with adequate cervical length (p < 0.0001), and shortened in those with a short cervix (p < 0.0001). USCL assessment during pregnancy proved to be the PTB risk-predicting tool, with CCS supplementation apt to increase its diagnostic value. No substantial impact on pregnancy outcomes could be linked to any particular PTB prevention mode (POG or PPV). However, during pregnancy, the USCL changes relating to CCS proved to be more critical in pregnancy outcomes.