Cara Pessel, MD et al American Journal of Obstetrics and Gynecology 2013

 Cervical length measurement in pregnancy has proved to be a useful tool in the identification of women who Are at risk of spontaneous preterm delivery.  Serial assessments of the cervix and weekly intramuscular injections of 17-alpha-hydroxyprogesterone caproate (17-OHPC)

 mechanism by which 17-OHPC reduces the risk of recurrent preterm delivery is not well established.  A previous study reported no difference in the rate of cervical shortening among women with a history of spontaneous preterm delivery according to 17-OHPC exposure.

aberrations in cervical remodeling may predispose women to recurrent preterm deliveries and progesterone may function by targeting these aberrations, we hypothesized that women who experience recurrent preterm delivery and were exposed to progesterone may exhibit a slower rate of cervical shortening when compared with women who were not exposed to 17-OHPC.

a retrospective study among women with history of spontaneous preterm delivery (defined as 1 spontaneous births between 16 weeks and 36 weeks 6 days’ gestation) who underwent serial cervical length assessments to monitor for cervical shortening in our institution between 2009 and 2012

Pregnancies with 1. major fetal anomalies, 2.vaginal progesterone use at any time in the index pregnancy, 3. <2 cervical length measurements 4. medically indicated preterm delivery, or 5. the presence or placement of an abdominal or vaginal cerclage were excluded.

 Electronic medical records were reviewed to abstract pertinent obstetric history, including the number of previous preterm deliveries, gestational age of each preterm delivery, and whether that pregnancy involved multiple gestations.  maternal age, race,ethnicity, prepregnancy and weight at delivery, type of provider (private maternal-fetal medicine specialist, private generalist obstetrician and gynecologist (OB/GYN), or government-insured OB/GYN low-risk clinic or high-risk maternal-fetal medicine clinic), use of in vitro fertilization, smoking status, and illicit drug use during pregnancy.

At our center, women with a history ospontaneous delivery at <37 weeks’ gestation are offered weekly treatment with 17-OHPC starting at 16 gestational weeks. Review of our electronic ultrasound database was used to record cervical length measurements (in millimeters) from weeks’ gestation

 The obstetrics ultrasound guidelines at Columbia University Medical Center require 3 measurements of the cervix that include at least 1 assessment while the patient performs the Valsalva maneuver. The shortest of the 3 cervical length values is reported clinically; this measurement was recorded into our database for each visit

Short cervix is defined at our institution as <25 mm, which represents the 10th percentile at 24 weeks’ gestation. Once this is identified in our ultrasound unit, patient treatment varies according to practitioner and individual patient details and may involve cerclage placement, the initiation of vaginal progesterone, or expectant treatment and observation

the goal of our protocol was to identify all women who may benefit from timesensitive interventions such as antenatal steroid and magnesium administration

 Of 17,400 deliveries from , 376 women with a history of spontaneous preterm delivery met inclusion criteria.  We excluded 139 women: major fetal anomalies, 5 women; the presence of placement of a cerclage (2 abdominal and 78 vaginal), 80 women; exposure to vaginal progesterone, 32 women; indicated preterm delivery, 22 women.  This resulted in 237 women for analysis. Of the included patients, 184 (77.6%) were exposed to 17- OHPC in the current pregnancy.

 Women who were exposed to 17-OHPC were, on average, 2.2 years younger None of the other characteristics, including previous uterine or cervical surgery, differed between the groups.  Subjects who were not exposed to 17-OHPC were more likely to have a previous preterm delivery that involved a multiple gestation  obstetric history of recurrent preterm delivery, gestational age at earliest preterm delivery, and history of at least 1 term delivery was similar between those who were exposed to 17-OHPC and those not.

The average rates of cervical shortening per week among term deliveries were 0.9 and 0.8 mm with and without 17-OHPC, respectively (P ¼.76). Among preterm deliveries, the corresponding rates were 0.8 and 1.2 mm, respectively, among women with and without 17-OHPC (P ¼.67).

Rates of spontaneous preterm delivery in the current pregnancy on exposure to 17-OHPC did not differ based.

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