Late‐stage Cesarean section causes recurrent early preterm birth: how to tackle this problem?

Abstract

About 500 000 preterm deliveries before 37 weeks' gestation occur annually in the USA. Worldwide, this figure is estimated to be 15 million each year, with serious associated health implications and high costs to families and society. The management and prevention of preterm birth is highly variable depending on the etiology. Recent studies have shown that Cesarean section (CS) performed late in labor or at full dilatation (FDCS) is associated with recurrent early preterm birth and late miscarriage. However, the clinical problem that FDCS poses in subsequent pregnancies is still under-recognized. In addition to raising awareness, further research is needed to understand the etiology of this association and to develop prevention and management strategies, particularly in light of the escalating CS rate.

Prospective Evaluation of the Ultrasound Signs Proposed for the Description of Uterine Niche in Nonpregnant Women

“…Intrapartum emergency CD are more likely to involve the cervix cervical tissue 31,32 and the risk increases as labour progressed and the lower segment is further stretched by the descent of the fetal presentation. 33,34 As the labour progresses, full cervical effacement causes the smooth muscle of the internal sphincter to migrate into the lower uterine segment 35 making it difficult for the surgeon to localise the upper cervix. This can explain the higher incidence of scars and niches below the vesicovaginal fold in the subgroup who had an emergent CD at > 4 cm in the present study (Table 2).…”

Prospective Evaluation of the Ultrasound Signs Proposed for the Description of Uterine Niche in Nonpregnant Women

“…Injury to the cervical morphology during CD performed late in labor may contribute to preterm birth in subsequent pregnancies. 4,6,36 Recent data have indicated that the uterine cervix is made a specialized sphincter at the internal os and the cervical smooth muscle cells may play a role in cervical remodeling as well as initiating and/or disseminating uterine contractility. 38 We found that women who had an emergency CD at cervical dilatation >4 cm presented with a significantly higher incidence of both their scar or a niche to be located below the vesicovaginal fold (Table 2), suggesting that this subgroup of women could be at higher risk of premature delivery in subsequent pregnancies.…”

“…When the CD was performed at a cervical dilatation ≤4 cm, there was a significantly ( P = .012) higher incidence of a uterine niche located above the vesicovaginal fold and a significantly ( P = .0002) lower proportion of cesarean scar below the vesicovaginal fold compared with those who had their CD at active stage of labor. Intrapartum emergency CD is more likely to involve the cervix cervical tissue 33,34 and the risk increases as labor progressed and the lower segment is further stretched by the descent of the fetal presentation 35,36 . As the labor progresses, full cervical effacement causes the smooth muscle of the internal sphincter to migrate into the lower uterine segment, 37 making it difficult for the surgeon to localize the upper cervix.…”

“…Injury to the cervical morphology during CD performed late in labor may contribute to preterm birth in subsequent pregnancies 4,6,36 . Recent data have indicated that the uterine cervix is made a specialized sphincter at the internal os and the cervical smooth muscle cells may play a role in cervical remodeling as well as initiating and/or disseminating uterine contractility 38 .…”

“…Intrapartum emergency CD is more likely to involve the cervix cervical tissue 33,34 and the risk increases as labor progressed and the lower segment is further stretched by the descent of the fetal presentation. 35,36 As the labor progresses, full cervical effacement causes the smooth muscle of the internal sphincter to migrate into the lower uterine segment, 37 making it difficult for the surgeon to localize the upper cervix. This can explain the higher incidence of scars and niches below the vesicovaginal fold in the subgroup who had an emergent CD at >4 cm in the present study (Table 2).…”