Cervical Conization Increase the Risk of Preterm and Very Preterm Birth in Assisted Reproductive Technology Twin Pregnancies

Cervical conization doubles the risk of preterm birth (PTB) and very preterm birth (VPTB) in assisted reproduction technology (ART) twin pregnancies. ART and cervical conization are both risk factors for PTB. Cervical conization included both cold knife cone and LEEP (loop electrosurgical excision procedure) but not cervical biopsies. Cervical morbidity (dysplasia and conization) was more often observed in ART pregnancies (6.2% of ART singletons and 5.4% ART twins) than in naturally conceived (NC) pregnancies (4.2% for NC singletons and 4.5% for NC twins), both for singletons and twins. In ART singleton deliveries, the PTB rate was 13.1 versus 8.2% in women with and without conization. In ART twin deliveries, the prevalence of PTB was 58.2 versus 41.3% in women with and without conization. Cervical dysplasia did not increase the risk of any of the other adverse outcomes in ART singletons or twins. After ART and prior conization, 58% of twin pregnancies versus 13% of ART singleton pregnancies result in PTB. There is a doubled risk of preterm delivery in ART twins with conization versus ART twins with no prior conization. Single-embryo transfer should always be recommended in women with prior conization irrespective of female age, embryo quality and prior number of ART attempts.