Real-world implementation studies have indeed shown significant decreases in SPTB when a policy of universal TVU CL screening in this specific population is implemented.
The authors found only an 8% sensitivity of TVU CL screening for SPTB using a cutoff of [less than or equal to] 25 mm at 16 0/7 to 22 6/7 weeks of gestation in 9,410 nulliparous women.
Third, outcomes data were not available for 469 women and, compared with women analyzed, these women were at higher risk for SPTB as they were more likely to be aged 21 years or younger, black, with less than a high school education, and single, all significant risk factors for SPTB.
Fourth, pregnancy losses before 20 weeks were excluded, and these could have been early SPTB; therefore, the sensitivity could have been decreased if women with this outcome were excluded.
Fifth, prior studies have shown that TVU CL screening in singletons without prior SPTB has a sensitivity of about 30% to 40%.
We have known for a long time that SPTB has many etiologies.
This is the first population in which TVU CL screening was first proven beneficial for prevention of SPTB. These women all should receive progesterone starting at 16 weeks because of the prior SPTB.
In women with a history of prior SPTB who are found to have a short cervix in the mid-trimester (cervical length of <2.5 cm prior to 24 weeks' of gestation), cerclage placement has been demonstrated to reduce the risk of recurrent PTB and adverse neonatal outcomes.
The absolute risk of SPTB is inversely proportional to the length of the cervix in that those women with a shorter cervix have a higher risk of SPTB.
One of the most frustrating areas has been reducing the risk of SPTB in women with other risk factors for PTB such as a multifetal gestation, preterm labor, or preterm premature rupture of membranes (PPROM) in the current pregnancy.
Progestins have been demonstrated to reduce the risk of PTB in certain populations of women at high risk of PTB, including women with a history of a prior SPTB of a singleton gestation and women carrying a singleton gestation who are found to have a short cervix in the midtrimester (TABLE 2).
If a woman with a prior SPTB is found to have a short cervix, she may benefit from cerclage placement to reduce her risk of recurrent PTB (in addition to continuing 17P).