522: Iatrogenic late preterm birth: etiology and consequences

Poster Session III

Fetus, Prematurity

520 Activation of the alternative pathway of complement is a feature of preterm parturition but not of spontaneous labor at term Edi Vaisbuch1, Roberto Romero2, Offer Erez1, Shali Mazaki-Tovi1, Juan Pedro Kusanovic1, Eleazar Soto1, Zhong Dong2, Tinnakorn Chaiworapongsa1, Sun Kwon Kim2, Giovanna Ogge2, Percy Pacora2, Lami Yeo1, Sonia S. Hassan1 1

Wayne State University School of Medicine, Detroit, Michigan, Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan

2

OBJECTIVE: Fragment Bb (FBb) is a marker for activation of the alternative pathway of the complement system. High concentrations of FBb in maternal blood, as early as the first trimester, are associated with subsequent spontaneous preterm delivery ⬍34 weeks of gestation (Lynch, AJOG 2008). The study aim was to determine whether spontaneous preterm labor with intact membranes (PTL), intra-amniotic infection/inflammation (IAI) or labor at term are associated with alterations in circulating maternal FBb concentrations. STUDY DESIGN: This cross-sectional study included the following groups: 1) preterm normal pregnancy (gestational age range 20-36 6/7 weeks, n⫽63); 2) women at term not in labor (n⫽70); 3) women at term in spontaneous labor (n⫽59); 4) patients with an episode of PTL who delivered at term (n⫽62); 5) PTL without IAI who delivered preterm (n⫽30); and 6) PTL with IAI who delivered preterm (n⫽67). Maternal plasma FBb concentrations were determined by ELISA. RESULTS: 1) Among patients with PTL, those who had a preterm delivery either with IAI (1.21 ␮g/mL, IQR 0.77-2.16 vs. 0.86 ␮g/mL, IQR 0.64-1.57; p⫽0.007) or without IAI (1.13 ␮g/mL, IQR 0.92-2.08; p⫽0.026) had a higher median maternal plasma FBb concentration than those who delivered at term; 2) There was no difference in the median plasma FBb concentration between patients who delivered preterm with and without IAI (p⫽0.9); 3) In contrast, spontaneous labor at term was not associated with a significant change in the maternal plasma FBb concentration (p⫽0.8); 4) Maternal plasma concentration of FBb did not change with gestational age (r ⫺0.28, p⫽0.8). CONCLUSION: 1) Preterm parturition is associated with alternative complement pathway activation; 2) Such activation is not detectable in spontaneous labor at term; 3) Intra-amniotic infection/inflammation does not explain the alternative complement pathway activation of preterm labor. Collectively, these observations suggest that preterm and term labor have fundamental differences in the regulation of innate immunity. 0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.686

521 One of every four patients with an asymptomatic short cervix (15mm) has subclinical intra-amniotic inflammation: implications for patient counseling and management Edi Vaisbuch1, Roberto Romero2, Shali Mazaki-Tovi1, Chia-Ling Nhan-Chang1, Juan Pedro Kusanovic1, Tinnakorn Chaiworapongsa1, Zhong Dong2, Lami Yeo1, Pooja Mittal1, Sonia S. Hassan1 1

Wayne State University School of Medicine, Detroit, Michigan, Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan

2

OBJECTIVE: The clinical management of a patient with a sonographic short cervix is a common obstetrical challenge. A fraction of patients with a short cervix have evidence of intra-amniotic inflammation (Kiefer, AJOG, 2009); however, the outcome of these patients has not been characterized. The purpose of this study was to determine the frequency and clinical significance of intra-amniotic inflammation in asymptomatic women in the mid-trimester of pregnancy with a sonographic short cervix. STUDY DESIGN: This cohort study included 47 asymptomatic women with a sonographic short cervix (15mm) diagnosed at 14-24 weeks who underwent amniocentesis for evaluation of the microbial state of amniotic cavity. Women with multifetal gestation, cerclage, or cervi-

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www.AJOG.org cal dilatation ⬎2cm were excluded. Intra-amniotic infection was defined as a positive amniotic fluid (AF) culture for microorganisms and intra-amniotic inflammation as an elevated AF MMP-8 concentration (⬎23ng/mL), as determined by ELISA. RESULTS: 1)The prevalence of intra-amniotic inflammation was 23.4% (11/47), and among patients with a negative AF culture 22.2% (10/45); 2)intra-amniotic infection and an AF WBC count 100 cells/ mm3 was found in 4.3% (2/47) and 6.4% (3/47) of patients, respectively; 3)AF MMP-8 concentration inversely correlated with cervical length (r ⫺0.44, p⫽0.002) and with diagnosis-to-delivery interval (r ⫺0.44, p⫽0.002); 4)patients with intra-amniotic inflammation had a higher rate of preterm delivery within one week [45.5% (5/11) vs. 5.6% (2/36); p⫽0.005] than those without intra-amniotic inflammation; and 5)women with intra-amniotic inflammation had a shorter median diagnosis-to-delivery interval than those without this condition (18 days, IQR 4-46 vs. 42 days, IQR 23-111; p⫽0.01). CONCLUSION: One of every four patients with a short cervix (15mm) before 24 weeks has subclinical intra-amniotic inflammation, and the risk of preterm delivery within 7 days for these patients is 45%. These findings have implications for the counseling and management of patients with an asymptomatic short cervix. 0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.687

522 Iatrogenic late preterm birth: etiology and consequences Cynthia Gyamfi1, Karin Fuchs1, Matthew Hoffman2 1

Columbia University Medical Center, New York, New York, Christiana Care Health System, Newark, Delaware

2

OBJECTIVE: The frequency of late preterm birth (LPB) has increased,

in part due to iatrogenic inductions between 34 0/7 to 36 6/7 weeks, but without new evidence to support these deliveries. We sought to determine the proportion of iatrogenic LPB that was evidence-based (EB) versus non evidence-based (NEB), and to compare the rates of NICU admission associated with each. STUDY DESIGN: We performed a retrospective cohort study of LPB in two institutions between January 2003 and July 2007. Spontaneous preterm labor and preterm premature rupture of the membranes were excluded. Records were reviewed to determine the indication for delivery. Cases were categorized either as EB (eg, severe preeclampsia/ eclampsia, abnormal fetal testing, abruption) or NEB. NICU admission rates were compared between groups, and potential confounders affecting admission were controlled for using logistic regression. RESULTS: We identified 2693 women with LPB. 32.3% (872/2693) had iatrogenic deliveries, with 56.7% delivered for NEB indications. Women with NEB deliveries were older (30.0 v. 28.6 years, p⫽0.001), pregnant with twins (18.8% v. 7.9%, p⬍0.001), had a private provider (80.3% v. 59.0%, p⬍0.001), and had more than one complicating factor (27.5% v. 10.1%, p⬍0.001). The most common NEB diagnoses were mild preeclampia (34.3%) and gestational hypertension (16.3%) with normal fetal testing, while the most common EB diagnoses were severe preeclampsia (50.1%) and abnormal fetal testing (13.7%). Infants of women in the NEB group were more likely to be 36 weeks (70.6% v. 29.4%, p⬍0.001). Despite this 56% of NEB deliveries resulted in NICU admissions. After controlling for confounders, early gestational age was the strongest predictor of NICU admission (34 v. 36 weeks, OR 12.0, 95% CI 6.5, 22.0). CONCLUSION: Over half of iatrogenic LPB occurred without EB indications. Creating evidence-based guidelines for delivery indications may have a significant impact on LPB. 0002-9378/$ – see front matter • doi:10.1016/j.ajog.2009.10.688

American Journal of Obstetrics & Gynecology Supplement to DECEMBER 2009