Routine Cervical Length Screening in IVF Pregnancies with Short Interval
Routine cervical length screening is NOT indicated for IVF singleton pregnancies, regardless of interpregnancy interval, as there is no evidence that IVF conception itself increases preterm birth risk requiring universal screening. However, if the IVF pregnancy is a multiple gestation (twins or higher), baseline cervical length assessment between 15-24 weeks is recommended, with screening discontinued after 25-26 weeks. 1
Singleton IVF Pregnancies
IVF conception alone does not warrant routine cervical length screening in the absence of other high-risk factors such as prior spontaneous preterm birth, as the available guidelines do not identify IVF as an independent indication for universal screening. 1, 2
The American College of Obstetricians and Gynecologists recommends cervical length screening only for high-risk singleton pregnancies, which includes women with prior spontaneous preterm birth—not IVF conception per se. 1, 2
A "short interval" between pregnancies (typically defined as <18 months) may represent an additional risk factor, but this alone does not trigger routine cervical length screening recommendations in current guidelines. 2
If cervical length screening is performed and measures ≤20 mm before 24 weeks, vaginal progesterone is strongly recommended (GRADE 1A) to reduce preterm birth risk. 2
For cervical lengths between 21-25 mm, vaginal progesterone should be considered based on shared decision-making (GRADE 1B). 2
Multiple Gestation IVF Pregnancies
For twin or higher-order IVF pregnancies, baseline transvaginal cervical length assessment is recommended as part of routine second-trimester evaluation between 15-24 weeks' gestation. 1
The Society for Maternal-Fetal Medicine explicitly recommends against routine transvaginal cervical length screening after 25-26 weeks' gestational age in multiple gestations, as the predictive value diminishes and no proven effective interventions exist. 1
Cervical length <15 mm between 15-24+6 weeks in twin pregnancies predicts preterm labor regardless of management strategies, making this the critical threshold rather than the 25 mm cutoff used in singletons. 1
Monochorionic twins have significantly shorter mean cervical lengths (32.8 mm) compared to dichorionic twins (34.9 mm), with higher rates of spontaneous preterm birth (53.1% vs 44.9%), but routine serial measurements beyond baseline assessment remain controversial. 1
Critical Clinical Caveats
Recent literature questions the utility of serial cervical length measurements even in high-risk populations, as effective interventions to prevent preterm birth remain limited once short cervix is identified. 1
Historically, measuring cervical length at each visit was suggested, but current evidence does not support this practice due to lack of proven effective interventions that change outcomes. 1
If cervical length screening is performed, it must be done via transvaginal ultrasound using standardized technique—transabdominal measurements are insufficient and unreliable. 1, 2
Cerclage is contraindicated (GRADE 1B) in patients without prior preterm birth history who have cervical length 10-25 mm in the absence of cervical dilation, even if discovered on screening. 2
17-alpha hydroxyprogesterone caproate (17-OHPC) should NOT be used for short cervix treatment (GRADE 1B), and cervical pessary is not recommended for singleton pregnancies with short cervix (GRADE 1B). 2