Use of fetal fibronectin in women at risk for preterm delivery

Fetal fibronectin, a large molecular weight glycoprotein produced in the chorion, is expressed in cervical and vaginal secretions in women with disruption of the choriodecidual [table: see text] junction by labor or by inflammation. The presence of FFN in vaginal or cervical secretions before 35 weeks is a moderately good predictor of preterm delivery. The absence of FFN is a strong predictor that preterm delivery is unlikely within the next 7 to 14 days, with NPVs exceeding 99% in some studies. The predictive power of FFN is stronger at earlier gestation ages (24-28 wks) than it is later [table: see text] in pregnancy and is stronger for short-term prediction (7-14 d) than for predicting overall outcome (however, it remains statistically significant for predicting delivery < 37 wks). Although use of FFN in the clinical setting may require some changes to common protocols (e.g., performing sterile speculum examination before digital cervical examination), the use of FFN in patients with suspected preterm labor appears to have significant utility in reducing unnecessary interventions in women with symptoms suggestive of preterm labor. In women without symptoms, the use of FFN may be most beneficial in providing reassurance to some women thought to be at high-risk for preterm delivery because of past obstetric history. Screening women without symptoms at low-risk with FFN is not yet recommended because effective interventions are not demonstrated for patients found to be positive.     

Cervicovaginal HCG and cervical length for prediction of preterm delivery in asymptomatic women at high risk for preterm delivery

Objective  To predict the risk of preterm birth (<37 weeks) or early preterm birth (<34 weeks) by cervicovaginal HCG and cervical length measured between 24–28 weeks of gestation in asymptomatic women at high risk for preterm birth. Methods  This study was conducted in the departments’ of Obstetrics & Gynaecology and Immunopathology of the Postgraduate Institute of Medical Education and Research, Chandigarh, India. In 75 pregnant women at high risk for preterm birth because of prior one on more preterm births due to spontaneous labour or ruptured membranes, cervicovaginal HCG and cervical length (by TVS) were measured between 24–28 weeks of gestation. These parameters were correlated individually and in combination for prediction of preterm birth. Results  Of the 75 women, 20 (26.7%) delivered <37 weeks and 6 (8%) delivered <34 weeks. To predict delivery <37 weeks, cervical length <2.95 cm had a sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of 75%, 80.1%, 71.4% and 90.7% respectively, and cervicovaginal HCG >4.75 mIU/ml had a sensitivity, specificity, PPV, and NPV of 70%, 61.81%, 40% and 85% respectively. To predict delivery <34 weeks, cervical length <2.65 cm had a sensitivity, specificity, PPV, and NPV of 50%, 85.50%, 23.08% and 95.16% respectively; and cervicovaginal HCG >14 mIU/ml had a sensitivity, specificity, PPV and NPV of 83.3%, 85.5%, 33.3% and 98.3% respectively. Cervical length was superior to predict delivery <37 weeks, whereas HCG was superior to predict delivery <34 weeks. Their combination was superior to predict preterm birth both <37 weeks or <34 weeks, than either parameter used alone. Conclusion  In high risk asymptomatic women, increased cervicovaginal HCG and reduced cervical length and between 24 to 28 weeks of gestation increased the risk of preterm delivery.     

Antenatal corticosteroids for fetal maturation in women at risk for preterm delivery

The available data unambiguously support the beneficial, short-term fetal effects of antenatal corticosteroids in women at risk for preterm delivery. There are still several incompletely addressed questions, including the use of corticosteroids in women with preterm premature rupture of membranes, the optimal corticosteroid preparation to be used, and the impact of repeated dosing. These issues are discussed in this review from the perspective of recent scientific evidence on the mechanisms responsible for positive short-term effects on survival and possible harmful long-term effects.     

Magnetic resonance imaging of the cervix in women at high risk for preterm delivery

Objectives.?To assess whether changes in signal intensity of cervical stroma layers on magnetic resonance imaging (MRI) are associated with spontaneous preterm delivery.

Methods.?Prospective cohort study of women admitted for threatened late miscarriage or preterm delivery between 18 and 34 weeks of gestation. We performed T2-weighted low-field MRI of the uterine cervix among 100 women. Cervical stromal differentiation, defined as the contrast between signal intensities of the inner and outer cervical layers, was classified as high, intermediate, or low by a radiologist blinded to the participant's clinical report. The main outcome measure was the proportion of spontaneous preterm delivery.

Results.?Thirty-six women had a spontaneous preterm delivery. The proportion of spontaneous preterm delivery for high, intermediate, and low stromal differentiation was 7/24 (29%), 21/64 (33%; risk ratio 1.1; 95% confidence interval [CI]: 0.6–2.3), and 8/12 (67%; risk ratio 2.3; 95% CI: 1.1–4.8), respectively. The risk of delivering within 7 days increased when stromal differentiation decreased, although the difference was not statistically significant.

Conclusions.?The risk of spontaneous preterm delivery is increased in women with low cervical stromal differentiation on MRI. This risk is also associated with short cervical length, a measurement easier and less costly to obtain by transvaginal ultrasound.     

17alpha-hydroxy-progesterone effects on cervical proinflammatory agents in women at risk for preterm delivery

We evaluated if the inhibitory effect of 17alpha-hydroxyprogesterone caproate (17P) on cervical ripening is mediated by cervical proinflammatory agents. Women with singleton pregnancy and intact membranes, between 25 and 33 weeks + 6 days, were randomly allocated either to observation (22 cases, controls) or to receive 341 mg of intramuscular 17P (23 cases, 17P group), twice a week, until 36 weeks. Just before randomization, 7 and 21 days later, a cervical swab for interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor alpha (TNF-alpha), and nitrates/nitrites (NOx) assays was collected. Moreover, an ultrasound measure of cervical length (CL) was performed at the same time. At randomization, both groups of women showed similar levels of cervical ILs and NOx. In the 17P group, cervical IL-1beta levels were significantly decreased at day 21 ( P = 0.036); in controls, they remained stable throughout the observation period. There was no significant change in IL-6, IL-8, TNF-alpha, and NOx in either group. Women in the control group had a progressive CL shortening until day 21 (median shortening of 4 mm), and this shortening was significantly less in the 17P group (median shortening of 2 mm; P = 0.017). In patients at risk of preterm labor, high-dose 17P simultaneously inhibits both cervical proinflammatory IL-1beta secretion and the progressive shortening of the cervix.     

Warning symptoms, uterine contractions, and cervical examination findings in women at risk of preterm delivery

The presence of various reputed warning signs of preterm labor, the frequency of contractions, and the presence of cervical examination findings and their value in predicting preterm labor and spontaneous preterm delivery were assessed. The frequency of contractions and all cervical examination findings increased during pregnancy, as did backache, pressure, and cramping. The frequency of diarrhea, discharge, and bleeding remained constant. Of the various warning signs, only diarrhea and discharge were associated with the diagnosis of preterm labor. None of the warning signs were associated with spontaneous preterm delivery. Various patterns of contractions tended to be associated with higher rates of preterm labor and preterm delivery, but results were generally not statistically significant. Most cervical examination findings were statistically associated with both preterm labor and preterm delivery.     

Evaluation of antenatal corticosteroid prescribing patterns among 984 women at risk for preterm delivery

Abstract

Objective: To evaluate the prescribing patterns of the first antenatal corticosteroids (ACS) course in our tertiary referral centre from 2005 until 2010.

Study design: We conducted a retrospective cohort study including all women who received ACS between 24⁺⁰ and 34⁺⁰ weeks of gestation. Main outcome measure was the number of women who delivered within 7?d after ACS administration. The time interval from administration to delivery was compared between women with different indications. Furthermore, all women delivering between 24⁺⁰ and 34⁺⁰ weeks of gestation who did not receive ACS were identified.

Results: 1008 women received ACS, 15 (1.5%) women were lost to follow up. Main indications were suspected preterm labour, preterm prelabour rupture of membranes, maternal indication, foetal indication and vaginal blood loss (VBL). Overall, 447 (45.4%) women delivered ≤7?d after ACS administration. This percentage was 13.6% in women with VBL and 61.5% in women with maternal indication. During the study period, 1267 women delivered before 34 weeks of gestation, 126 (9.9%) women did not receive ACS.

Conclusions: The time interval from ACS administration to delivery differs per indication. Women with VBL are most often over treated. The timing of the first ACS course should be improved.     

Multicentred controlled trial of cervical cerclage in women at moderate risk of preterm delivery

A total of 506 women at moderate risk of preterm delivery were randomly allocated to either cervical cerclage or a control group. Significantly more women in the group allocated to cerclage were admitted to hospital for reasons other than the operation and more received oral tocolytic drugs. There were also more caesarean sections and more preterm deliveries in the women allocated to cerclage although the differences between the two groups were small and not statistically significant.     

Adipokinins in pregnancies at risk of preterm delivery

Objective: To compare adipokinins between women experiencing preterm labor (PTL) and prior preterm deliveries (PTD).

Study design: In this prospective observational cohort, 110 women with a singleton <35 weeks at increased risk of PTD were studied. Serum leptin, adiponectin, and resistin were obtained at three times (23–34 weeks, 35–36 weeks, at delivery) and analyzed via enzyme-linked immunosorbent assay. The adipokinins were compared across time and between PTL (n?=?59) and prior PTD (n?=?51) groups using generalized estimated equation models.

Results: There were no differences in leptin, adiponectin, or resistin levels over the three times between the PTL and PTD groups. There was a trend toward higher leptin levels (p?=?0.06 unadjusted analysis, p?=?0.09 adjusted analysis) at 23–34 weeks. When stratified by body mass index (BMI), there were differences in leptin (p?p?=?0.77 for BMI?≥?30) and adiponectin (p?=?0.04 for BMI?p?=?0.09 for BMI?≥?30), but not in resistin over the three times between the PTL and prior PTD groups.

Conclusion: There were no significant differences in adipokinins in women with PTL and a prior PTD. The trends toward higher leptin levels at 23–34 weeks in women with PTL may represent a compensatory response and require further evaluation in the study of treatments for PTL.     

Multicentred controlled trial of cervical cerclage in women at moderate risk of preterm delivery

Summary. A total of 506 women at moderate risk of preterm delivery were randomly allocated to either cervical cerclage or a control group. Significantly more women in the group allocated to cerclage were admitted to hospital for reasons other than the operation and more received oral toco-lytic drugs. There were also more caesarean sections and more preterm deliveries in the women allocated to cerclage although the differences between the two groups were small and not statistically significant.     

Role of ultrasound in screening patients at risk for preterm delivery

The ultrasound assessment of the cervix has contributed to the understanding of the pathways to preterm birth. Transvaginal ultrasound measurement of the cervix provides an objective and noninvasive tool for the evaluation of cervical status. Despite widespread use of this procedure, standardization of measurement indications, technique, and interval between examinations has not been achieved. The American College of Radiology has recently recommended that the cervix and lower uterine segment be imaged as part of every obstetric ultra-sound examination in the second trimester. These guidelines specifically suggest a search for a short cervix (less than 30 mm) or funneling. The expert panel on women's imaging further recommended evaluating the cervix sonographically on both the initial examination and all follow-up examinations for twin gestations. The American Institute of Ultrasound in Medicine guidelines indicate that evaluation of the uterus, including cervix, should be performed, but does not indicate specifically that the cervix should be measured. In contrast, the American College of Obstetricians and Gynecologists, although recognizing that cervical length assessment may be helpful in predicting the risk of preterm delivery (particularly from a negative predictive value), does not recommend routine use of cervical length measurement because of the lack of proved treatment or intervention methods. A review of the literature suggests that at the time of this writing the role of routine screening of low-risk women with cervical length assessment by ultrasound is not supported. In contrast, in women at risk for preterm delivery(eg, women with a prior history of preterm birth or women with multiple gestations) cervical length assessment may be useful for its negative predictive value. At present, however, there is no therapeutic intervention that has been proved to decrease the risk of preterm delivery in women with a documented cervix on ultrasound.     

Frequency and significance of preterm delivery in twin pregnancies.

OBJECTIVE: We investigated the frequency of preterm delivery and its influence on the neonatal outcome in twin pregnancies at a perinatal center. Are there differences in the course of twin pregnancies with preterm or term delivery? METHOD: A retrospective investigation was carried out at the Department of Obstetrics on 502 twin pregnancies and deliveries between 1978 and 1993. Pregnancy history and clinical parameters were compared among preterm (<37+0 weeks) and term deliveries. RESULT: Median duration of all twin pregnancies was 36+3 weeks of gestation. In the preterm group, preterm labor was more frequent, both, the first and the second neonate had lower birth weight and were more often admitted to the neonatal intensive care unit (NICU) where they stayed longer than full-term neonates needing intensive care. Perinatal deaths occurred only in the preterm group. CONCLUSIONS: The incidence of preterm delivery is significantly elevated in twin pregnancies and consequently the incidence of low- and very-low-birth-weight-infants and perinatal mortality. Preterm delivery is the main reason why twin pregnancies are at a higher risk for an adverse neonatal outcome and thereby cause considerable costs.     

The risk of preterm delivery in women from different ethnic groups

Objective To examine whether routinely measured variables explained the increased risk of preterm delivery in some UK ethnic groups.
Design Cross sectional study of deliveries recorded in the Child Health Record System.
Setting North Birmingham, UK.
Population All North Birmingham women delivering singletons, 1994–1997 inclusive.
Method Logistic regression.
Main outcome measures Odds ratio (OR) and 95% confidence interval (CI) for preterm delivery, defined as less than 37 weeks, less than 34 weeks and less than 28 weeks, unadjusted and adjusted for maternal age, an area-based socio-economic status measure, and marital status, year of birth, fetal sex and past obstetric history.
Results For Afro-Caribbean women, the ORs (95% CIs) were: for delivery less than 37 weeks, 1.44 (1.26–1.64) unadjusted and 1.22 (1.07–1.41) adjusted; for delivery less than 34 weeks, 1.55 (1.25–1.92) unadjusted and 1.29 (1.02–1.61) adjusted; for delivery less than 28 weeks, 1.66 (1.08–2.55) unadjusted and 1.32 (0.84–2.06) adjusted. For African women, the risk of delivery less than 37 weeks was not significantly raised; for delivery less than 34 weeks, the OR (95% CI) was 1.88 (0.99–3.58) unadjusted and 1.78 (0.93–3.40) adjusted; for delivery less than 28 weeks, the OR (95% CI) was 4.02 (1.60–10.12) unadjusted and 4.10 (1.66–10.16) adjusted. In Afro-Caribbeans, deprivation and marital status explained the differences between the unadjusted and adjusted ORs. There was a linear relation between deprivation and preterm delivery for all ethnic groups, except for Asians.
Conclusions Factors associated with deprivation and marital status explain about half of the excess of preterm births in Afro-Caribbeans, but not Africans. The risk of preterm delivery might not be related to deprivation in Asians.