If the FDA removes 17P from the market, my approach with at-risk patients will be as follows:
- I will encourage all at-risk women to eliminate obvious risk factors, such as smoking, illicit drug use, and excessive physical activity.
- I will encourage optimal nutrition and appropriate weight gain.
- I will test all patients for chlamydia, gonorrhea, and bacterial vaginosis and treat women who are infected.
- After the patient completes the first trimester, I will treat her with micronized progesterone, 200 mg daily, intravaginally. I will continue this medication until 36 to 37 weeks.
- I will perform an assessment of cervical length at 16, 20, and 24 weeks' gestation. In patients with demonstrable cervical shortening, I will perform a cerclage.
Rational management options for reducing risk of preterm delivery
Alex C. Vidaeff, MD, MPH
Most women who experience a spontaneous preterm delivery (sPTD) do not deliver prematurely in subsequent pregnancies.3 Two recent systematic reviews, in 2014 and 2017, found an overall risk of recurrent sPTD of 20.2% and 30%, respectively.4,5 These numbers are closer to the background event rate of 21.9% in the PROLONG trial, while only a few women have a recurrence risk of more than 50%, as in the Meis MFMU trial.1,2 A public health recommendation cannot be made for an intervention that is expected to work only in rare cases and fail in a majority of cases. Therefore, 17P is no longer a viable option for preventing recurrence in pregnant women with a history of sPTD, with only rare possible exceptions.
What evidence-based alternatives can be offered to pregnant women who had a previous sPTD?
Ultrasound assessment of cervical length has emerged as an effective prognosticator for recurrence in women with a prior sPTD, being able to predict 65.4% of sPTDs at a false-positive rate of 5%.6,7 Furthermore, sonographic cervical length measurements identify high-risk women who may not need any intervention. It has been shown that, among women with prior sPTD who maintain a normal cervical length up to 24 weeks, more than 90% will deliver at 35 weeks or after without intervention.8
In the United States, interventions to reduce sPTD, once a short cervix has been identified, include vaginal progesterone supplementation and cerclage. The benefit from vaginal progesterone has been documented by an individual patient data meta-analysis, while the benefit of cerclage has been highlighted in a Cochrane Review.9,10 The results of an adjusted indirect comparison meta-analysis suggest that both interventions are equally effective.11 Therefore, the decision on how best to minimize the risk of recurrent sPTD must be individualized based on historical and clinical circumstances, as well as the woman's informed choice.
Based on current data, the following approach appears rational to me:
- Cervical ultrasound surveillance between 16 and 24 weeks' gestation to identify the subgroup of women at significantly increased risk of sPTD recurrence.
- With cervical length ≤ 25 mm, vaginal progesterone supplementation may be considered. Preferential consideration for progesterone may be given when lower genital tract inflammation is suspected, given the possible anti-inflammatory action of progesterone.12,13
- If cervical shortening progresses to 15 to 20 mm, cerclage may be considered. Waiting for a cervix < 15 mm may be unadvisable. In conditions of a very short cervix, frequently dilated, with exposure of the fetal membranes, ascending subclinical intra-amniotic infection already may be present, reducing the efficacy of cerclage. Preferential consideration for cerclage also may be given with 2 sPTDs or mid-trimester losses or with a history of a successful cerclage.
Continue to: Screen cervical length early, and use cerclage or vaginal progesterone as appropriate...