Faculty Bibliography

Objective: To assess the diagnostic accuracy of vaginal fetal fibronectin (fFN) sampling for predicting preterm birth in asymptomatic women carrying triplet gestations. Methods: An historical cohort of patients carrying triplet gestations between 1998 and 2010 was identified from a single practice by chart review. All patients were screened with fFN testing at 2-3 week intervals from 22 weeks to 32 weeks of gestation. Outcomes evaluated were spontaneous preterm birth prior to 28, 30, and 32 weeks' gestation and delivery within 2 and 3 weeks of testing. Results: There were 56 pregnancies that met criteria for inclusion. For delivery prior to 30 weeks' gestation, the test had a sensitivity of 75%, a specificity of 85.4%, a positive predictive value of 46.2%, a negative predictive value of 95.3%, positive likelihood ratio of 5.13, and a negative likelihood ratio of 0.29 (p < 0.0001). For delivery within 3 weeks of a single fFN assessment, the test had a sensitivity of 53.3%, a specificity of 95.8%, a positive predictive value of 53.3%, a negative predictive value of 95.8%, positive likelihood ratio of 12.7 and negative likelihood ratio of 0.48 (p < 0.0001). Conclusion: Fetal fibronectin testing provides moderate to high prediction of spontaneous preterm birth in triplet gestations.

OBJECTIVE: To examine the effect of obesity on maternal and neonatal outcomes in women diagnosed with gestational diabetes mellitus (GDM) and managed with diet only, glyburide, or insulin. STUDY DESIGN: Women with singleton gestations enrolled for outpatient services diagnosed with GDM and without history of pregnancy-related hypertension at enrollment or in a prior pregnancy were identified in a database. Women with GDM controlled by diet only (n = 3918), glyburide (n = 873), or insulin without prior exposure to oral hypoglycemic agents (n = 2229) were included. Pregnancy outcomes were compared for obese versus nonobese women within each treatment group and also compared across treatment groups within the obese and nonobese populations. RESULTS: Within each treatment group, obesity was associated with higher rates of cesarean delivery, pregnancy-related hypertension, macrosomia, and hyperbilirubinemia (all p < 0.05). Higher rates of pregnancy-related hypertension and hyperbilirubinemia were observed in women receiving glyburide. CONCLUSION: Obesity adversely affects pregnancy outcome in women with GDM. Higher rates of pregnancy-related hypertension and hyperbilirubinemia were observed in pregnant women receiving glyburide.

OBJECTIVE: : To estimate the likelihood of cesarean delivery and length of labor in twin pregnancies undergoing induction of labor as compared with singleton pregnancies. METHODS: : This was a retrospective cohort study of 100 patients with twin pregnancy in one maternal-fetal medicine practice undergoing induction of labor from 2005 to 2012. The control group was 100 randomly selected patients in the same practice with a singleton pregnancy undergoing induction of labor over the same time period. The primary outcome was mode of delivery (vaginal or cesarean). RESULTS: : The likelihood of cesarean delivery did not differ between the groups (19% in twins compared with 21% in singletons, P=.724) nor did the time from induction to vaginal delivery (median and interquartile time 9.7 [5.5-12.5] hours in twins compared with 10.4 [6.6, 14.1] hours in singletons, P=.255). Results were not different when we looked at nulliparous patients only or multiparous patients only. On adjusted analysis of risk factors for cesarean delivery in patients undergoing induction, twin pregnancy was not independently associated with cesarean delivery. CONCLUSION: : Patients with twin pregnancies undergoing induction of labor have a similar risk of cesarean delivery and a similar length of labor as patients with singleton pregnancies undergoing induction of labor. LEVEL OF EVIDENCE: : II.

OBJECTIVES: The purpose of this study was to evaluate the gestational age at sonographic detection of placenta previa as a predictor of previa persistence until delivery in twin gestations. METHODS: A retrospective cohort of twin pregnancies with placenta previa in a single ultrasound unit was analyzed from 2005 to 2010. Pregnancies were ascertained from a database. Diagnoses were confirmed by transvaginal imaging. Previa was categorized as complete if the placenta completely covered the internal os or marginal if the inferior placental edge reached within 2 cm. Gestational ages were grouped into intervals from 15 to 35 weeks. The study outcome was placenta previa at delivery. Only twin pregnancies at 25 weeks' gestation and later were analyzed using nonparametric statistics as appropriate, with P < .05 as significant. RESULTS: Placenta previa was detected in 120 twin pregnancies in the second trimester: 32 complete and 88 marginal. Of those with placenta previa at 15 to 19, 20 to 23, 24 to 27, 28 to 31, and 32 to 35 weeks, previa persisted until delivery in 8.3%, 19.2%, 50%, 75%, and 92.5%, respectively. Only at 15- to 19- and 20- to 23-week intervals was complete previa more likely to persist than marginal previa (P < .001). CONCLUSIONS: The likelihood of placenta previa persistence in twins is dependent on the gestational age at sonographic detection. Only at earlier gestations does the type of previa affect its persistence. As gestational age advances, the likelihood of resolution of placenta previa diminishes regardless of the type noted.

To estimate the risk of preterm birth in asymptomatic women with twin pregnancies with a normal cervical length (CL) and a positive fetal fibronectin (fFN), we reviewed a retrospective cohort of twin pregnancies delivered in our practice from 2005 to 2010. Patients were screened from 22 to 32 weeks with CL and fFN at 2- to 4-week intervals. We examined 244 patients with twin pregnancies and a normal CL (>25 mm) between 22 and 32 weeks and compared outcomes based on the fFN result. Fourteen (5.7%) patients had a positive fFN and 230 (94.3%) patients had a negative fFN. Positive fFN was associated with an increased the risk of spontaneous preterm birth < 37 weeks (85.7% versus 38.3%, p = 0.001), < 35 weeks (50% versus 11.8%, p < 0.001), < 34 weeks (35.7% versus 6.9%, p < 0.001), and < 32 weeks (21.4% versus 2.2%, p < 0.001). On adjusted analysis, a positive fFN was independently associated with preterm birth < 32 weeks (odds ratio 6.8, 95% confidence interval 1.42, 32.2) and gestational age at delivery (p = 0.001). In the setting of a normal CL, a positive fFN is significantly associated with preterm birth in asymptomatic twin pregnancies. Contingency model screening of fFN in asymptomatic twin pregnancies solely based on CL evaluation may fail to identify a cohort of at-risk patients.

17 alpha hydroxyprogesterone caproate is a synthetic form of the natural progestin 17-alpha hydroxyprogesterone that is US FDA approved for the prevention of recurrent spontaneous preterm birth in women with a history of a prior singleton preterm birth. For women with a history of a prior spontaneous preterm birth between 20 weeks and 36 weeks and 6 days of gestation, the use of 17-alpha hydroxyprogesterone caproate has been shown to reduce the risk of recurrent preterm birth by more than 30%. This medication is the only drug currently FDA approved for the prevention of preterm birth, and it is the first drug the FDA has approved for use exclusively during pregnancy in approximately 15 years

OBJECTIVES: The purpose of this study was to estimate the association between second-trimester estimated fetal weight and fetal growth restriction in twin pregnancies. METHODS: A historical cohort of 306 twin pregnancies from a single center was analyzed. Estimated fetal weight and discordance at 18 to 24 weeks were calculated. Patients with a fetus whose second-trimester estimated fetal weight was below the 10th percentile were compared to patients with both fetuses at or above the 10th percentile. Also, patients with second-trimester discordance of 15% or greater were compared to patients with discordance of less than 15%. RESULTS: Second-trimester discordance was significantly smaller than birth weight discordance (mean discordance +/- SD, 7.41% +/- 6.06% versus 11.43% +/- 9.6%, respectively; P < .001). Patients with second-trimester discordance of 15% or greater were significantly more likely to deliver a twin with a birth weight below the 10th percentile for gestational age (67.7% versus 44.1%; P = .012) and below the 5th percentile for gestational age (41.9% versus 22.8%; P = .019). Patients with a second-trimester estimated fetal weight below the 10th percentile were significantly more likely to deliver a twin with a birth weight below the 10th percentile for gestational age (65.5% versus 44.5%; P = .031) and below the 5th percentile for gestational age (55.2% versus 21.5%; P < .001). CONCLUSIONS: In twin pregnancies, second-trimester estimated fetal weight below the 10th percentile and discordance of 15% or greater are associated with fetal growth restriction.