Prevention of preterm birth

Recurrent Risk of Preterm Birth in the Third Pregnancy in Korea

BACKGROUND

Although preterm delivery is the most common cause of infant morbidity and mortality, an obvious cause cannot be found in most cases. Preterm delivery is known to be the most important risk factor for preterm birth in a subsequent pregnancy. We aimed to evaluate the recurrence rate of premature births for subsequent pregnancies in women with a history of a preterm birth.

METHODS

Study data were collected from the Korea National Health Insurance (KNHI) claims database and data from a national health-screening program for infants and children. We enrolled women who had their first delivery between January 1, 2007 and December 31, 2007 and a subsequent delivery before 2014.

RESULTS

Preterm delivery had a significant higher risk of preterm birth in a subsequent singleton pregnancy. The risk of preterm birth at second pregnancy was 2.2% in women whose first delivery at ≥ 37 weeks and 18.6% in women whose first delivery at < 37 weeks (relative risks [RR], 8.64; 95% confidence interval [CI], 7.94-9.40). In the analysis of the third pregnancy, we compared women with an initial term birth followed by preterm birth and women with an initial preterm birth followed by a subsequent term birth. A history of a just preceding preterm birth at < 37 weeks was the most relevant factor for recurrence of preterm delivery in a subsequent pregnancy (26.6%, RR, 4.01; 95% CI, 2.45-6.58).

CONCLUSION

We found that the prognosis of a third pregnancy was more closely related to the outcome of the second pregnancy to that of the first pregnancy.

Early-onset preeclampsia is associated with perinatal mortality and severe neonatal morbidity

OBJECTIVE

To evaluate neonatal outcomes of pregnancies complicated by early-onset preeclampsia (PE) and compare these outcomes to those of gestational age matched neonates born to mothers whose pregnancy was not complicated by early-onset PE.

METHODS

We analyzed the outcome in 97 neonates born to mothers with early-onset PE (24-32 weeks amenorrhea at diagnosis) and compared it to that of 680 gestational age-matched neonates born between 25-36 weeks due to other etiologies and admitted to the Neonatal Intensive Care Unit (NICU) of a tertiary referral hospital in the Netherlands. We used Chi-square test, Wilcoxon test, and logistic regression analyses.

RESULTS

Neonates born to PE mothers had a higher perinatal mortality (13% vs. 7%, p = 0.03) and infant mortality (16% vs. 9%, p= 0.03), a 20% lower birth weight (1150 vs. 1430 g, p<0.001), were more often SGA (22% vs. 9%, p < 0.001) and had more neonatal complications as compared to neonates born to mothers without PE.

CONCLUSIONS

Overall adverse perinatal outcome is significantly worse in neonates born to mothers with early-onset PE. The effect of early-onset PE on perinatal mortality seems partially due to SGA. Whether these differences are due to uteroplacental factors or intrinsic neonatal factors remains to be elucidated.

Placental genome and maternal-placental genetic interactions: a genome-wide and candidate gene association study of placental abruption

While available evidence supports the role of genetics in the pathogenesis of placental abruption (PA), PA-related placental genome variations and maternal-placental genetic interactions have not been investigated. Maternal blood and placental samples collected from participants in the Peruvian Abruptio Placentae Epidemiology study were genotyped using Illumina's Cardio-Metabochip platform. We examined 118,782 genome-wide SNPs and 333 SNPs in 32 candidate genes from mitochondrial biogenesis and oxidative phosphorylation pathways in placental DNA from 280 PA cases and 244 controls. We assessed maternal-placental interactions in the candidate gene SNPS and two imprinted regions (IGF2/H19 and C19MC). Univariate and penalized logistic regression models were fit to estimate odds ratios. We examined the combined effect of multiple SNPs on PA risk using weighted genetic risk scores (WGRS) with repeated ten-fold cross-validations. A multinomial model was used to investigate maternal-placental genetic interactions. In placental genome-wide and candidate gene analyses, no SNP was significant after false discovery rate correction. The top genome-wide association study (GWAS) hits were rs544201, rs1484464 (CTNNA2), rs4149570 (TNFRSF1A) and rs13055470 (ZNRF3) (p-values: 1.11e-05 to 3.54e-05). The top 200 SNPs of the GWAS overrepresented genes involved in cell cycle, growth and proliferation. The top candidate gene hits were rs16949118 (COX10) and rs7609948 (THRB) (p-values: 6.00e-03 and 8.19e-03). Participants in the highest quartile of WGRS based on cross-validations using SNPs selected from the GWAS and candidate gene analyses had a 8.40-fold (95% CI: 5.8-12.56) and a 4.46-fold (95% CI: 2.94-6.72) higher odds of PA compared to participants in the lowest quartile. We found maternal-placental genetic interactions on PA risk for two SNPs in PPARG (chr3:12313450 and chr3:12412978) and maternal imprinting effects for multiple SNPs in the C19MC and IGF2/H19 regions. Variations in the placental genome and interactions between maternal-placental genetic variations may contribute to PA risk. Larger studies may help advance our understanding of PA pathogenesis.

Abnormal Progesterone and Corticotropin Releasing Hormone Levels are Associated with Preterm Labour

Introduction: This study examined whether maternal plasma progesterone and corticotropin releasing hormone (CRH) concentrations can predict the likelihood of preterm labour. Materials and Methods: Maternal plasma progesterone and CRH concentrations were examined in a total of 51 women. The subject cohort included 20 women who were followed from the beginning of the third trimester (28 to 34 weeks gestation), half of whom delivered early preterm and half of whom were not in labour and subsequently delivered at full term (n = 10 per group). In a follow-up experiment, 31 women who were admitted during labour for delivery were examined, 15 of whom delivered preterm and 16 of whom delivered at full term. Comparisons between women who delivered preterm and those who delivered at full term were made by t-tests. Results: Mean progesterone concentration was approximately 30% lower at 28 to 34 weeks gestation in women who delivered prematurely than in women who delivered at term (P <0.001). Meanwhile, mean CRH concentration was 6-fold higher at 28 to 34 weeks gestation in women who experienced spontaneous preterm labour than in those who went into labour at term (P <0.001). Preterm mothers had lower progesterone (P <0.05) and CRH (P <0.01) levels during active labour than full-term mothers. Progesterone levels normalised within 24 hours of delivery in preterm mothers, while CRH levels remained slightly elevated (P <0.01). Conclusions: Maternal progesterone and CRH measurements taken early in the third trimester may be of use as biochemical markers of pregnancies at high risk of premature labour. Introduction: This study examined whether maternal plasma progesterone and corticotropin releasing hormone (CRH) concentrations can predict the likelihood of preterm labour. Materials and Methods: Maternal plasma progesterone and CRH concentrations were examined in a total of 51 women. The subject cohort included 20 women who were followed from the beginning of the third trimester (28 to 34 weeks gestation), half of whom delivered early preterm and half of whom were not in labour and subsequently delivered at full term (n = 10 per group). In a follow-up experiment, 31 women who were admitted during labour for delivery were examined, 15 of whom delivered preterm and 16 of whom delivered at full term. Comparisons between women who delivered preterm and those who delivered at full term were made by t-tests. Results: Mean progesterone concentration was approximately 30% lower at 28 to 34 weeks gestation in women who delivered prematurely than in women who delivered at term (P <0.001). Meanwhile, mean CRH concentration was 6-fold higher at 28 to 34 weeks gestation in women who experienced spontaneous preterm labour than in those who went into labour at term (P <0.001). Preterm mothers had lower progesterone (P <0.05) and CRH (P <0.01) levels during active labour than full-term mothers. Progesterone levels normalised within 24 hours of delivery in preterm mothers, while CRH levels remained slightly elevated (P <0.01). Conclusions: Maternal progesterone and CRH measurements taken early in the third trimester may be of use as biochemical markers of pregnancies at high risk of premature labour.

Risk factors of preterm delivery in HIV-infected pregnant women receiving zidovudine for the prevention of perinatal HIV

AIM

Several studies have shown that preterm delivery, a primary cause of perinatal mortality and morbidity, is more frequent in HIV-positive women. This study aimed to determine factors associated with prematurity in HIV-infected women and identify risks for which specific interventions could be targeted.

METHODS

Data were prospectively collected in a clinical trial assessing the efficacy of different zidovudine prophylaxis durations for the prevention of perinatal HIV transmission in Thailand. Characteristics associated with prematurity - delivery before 37 weeks--were assessed using univariate and multivariate logistic regression and were subsequently used to identify subgroups of women at risk.

RESULTS

Among 979 women, independent prematurity risk factors were: viral load <3.5 or >4.5 log copies/mL; hemoglobin > 11.5 g/dL; weight gain <0.25 kg/week; and body mass index <20 kg/m2. These factors allowed us to define four subgroups with an expected probability of prematurity increasing from 3% to 30%. The two subgroups with the highest expected probability of prematurity were considered to be 'at risk' as opposed to the two lowest (odds ratio = 2.6, 95% confidence interval: 1.7-4.0) and the sensitivity and specificity of the prediction were 51% and 71%, respectively.

CONCLUSION

In this study, four risk factors of preterm delivery were identified allowing the identification of subgroups at increasing risk of prematurity. Adequate nutrition and the provision of highly active antiretroviral therapy during pregnancy as recommended by the World Health Organization for the prevention of perinatal transmission for immunocompromised women in resource-constrained countries may reduce the risk of premature delivery.

Comparison of Bedside Test Kits for Prediction of Preterm Delivery: Phosphorylated Insulin-like Growth Factor Binding Protein-1 (pIGFBP-1) Test and Fetal Fibronectin Test

Objective: The objective of the study was to compare the effectiveness of bedside test kits for pIGFBP-1 and fetal fibronectin test in predicting preterm delivery. Materials and Methods: Patients presenting with symptoms of preterm labour between 24 and 34 weeks of gestation were recruited. Both pIGFBP-1 and fetal fibronectin bedside tests were performed. Managing obstetricians and patients were blinded to the pIGFBP-1 and fetal fibronectin results. Tocolysis and steroid therapy were administered to all the recruited patients. Outcome data were collected after delivery. Results: One hundred and eight patients were recruited into the study. Fourteen patients had to be excluded from the final analysis due to incomplete data and failure to meet inclusion criteria. Ninety-four patients had complete data for analysis. Among those with negative pIGFBP-1 and fetal fibronectin results, the median [±standard deviation (SD)] gestational age at delivery was 37.4 weeks (±2.8 weeks) and 37.4 weeks (±2.1 weeks), respectively. Among those with positive pIGFBP-1 and fetal fibronectin results, the median (±SD) gestational age at delivery was 32.9 weeks (±4.0 weeks) and 34.2 weeks (±4.2 weeks), respectively (P <0.001 for both pIGFBP-1 and fetal fibronectin). A positive result with either test was associated with a significantly reduced admission-to-delivery interval. The median admission-to-delivery interval was 2.8 weeks shorter in the group with positive pIGFBP-1 results compared to those with a negative pIGFBP-1 result (2.3 weeks compared with 5.1 weeks) (P <0.001). This is 1.8 weeks shorter in the group with positive fibronectin results, compared to those with a negative result (3.3 weeks compared with 5.1 weeks) (P = 0.002). Both pIGFBP-1 and fetal fibronectin tests have high negative predictive value (NPV) in predicting risk of delivery within 48 hours, 7, or 14 days (1.00; 0.92; 0.92 and 0.97; 0.89; 0.89, respectively). Conclusions: Both pIGFBP-1 and fetal fibronectin tests are effective adjuvant bedside test kits for the prediction of preterm delivery in patients presenting with signs or symptoms of preterm labour. pIGFBP-1 has the higher NPV of 1.00 in predicting risk of delivery within 48 hours. Keywords: Early delivery, Labour ward, Objective test

Epidemiology of preterm birth and its clinical subtypes

Preterm birth (<37 weeks) complicates 12.5% of all deliveries in the USA, and remains the leading cause of perinatal mortality and morbidity, accounting for as many as 75% of perinatal deaths. Despite the recent temporal increase in preterm birth, efforts to understand the problem of prematurity have met with little success. This may be attributable to the under-appreciation of the etiologic heterogeneity of preterm birth as well as the heterogeneity in its underlying clinical presentations--spontaneous onset of labor, preterm premature rupture of membranes, and medically indicated preterm birth. In this paper, we review data regarding preterm births with particular focus on its incidence, temporal trends, and recurrence. Studies of births from the USA indicate that the recent temporal increase in the overall preterm birth rate is driven by an impressive concomitant increase in medically indicated preterm birth. However, the largest temporal decline in perinatal mortality has also occurred among medically indicated preterm births (relative to other clinical subtypes), suggesting that these obstetric interventions at preterm gestational ages are associated with a reduction in perinatal mortality. Recent data indicate that spontaneous preterm birth is not only associated with increased recurrence of spontaneous, but also medically indicated, preterm birth, and vice versa. This suggests that the clinical subtypes may share common underlying etiologies. Since medically indicated preterm birth accounts for as many as 40% of all preterm births, efforts to understand the reasons for such interventions and their impact on short- and long-term morbidity in newborns is compelling. Further research is necessary in order to understand the mechanisms and etiology of preterm birth, thus leading to the possibility of effective preventive or therapeutic strategies.

Suppression of IL-2 and IFN-gamma production in women with spontaneous preterm labor

AIMS

To determine the TH-1/TH-2 cytokine pattern in peripheral blood leukocytes (PBL) in late second- and third trimester in normal pregnancies, in comparison to patients with spontaneous preterm delivery (PTD; < 37 completed weeks' gestation).

METHODS

A cross-sectional retrospective study was performed in a tertiary care obstetric unit with healthy non-pregnant women (n=7); healthy pregnant women (n=25); patients (n=25) with preterm labor (defined as uterine contractions or changes in cervical length). The phenotypic analysis of TH-1/TH-2 immune deviation was examined in PBL.

RESULTS

26% PTD (n=13) were recorded. Patients delivering at term (n=37, 74%) were characterized by an upregulation of IL-2, IFN-gamma and IL-4 production during weeks 20-25, followed by a strong suppression in cytokine production, except for TGF-beta. Towards the end of pregnancy cytokine levels returned to normal as observed in non-pregnant women. In contrast, PTD showed an inverse pattern for IL-2 and IFN-gamma with marked suppression in IL-2 and IFN-gamma production between weeks 20-25, followed by a strong stimulation of these cytokines. No differences were observed in IL-4 and TGF-beta production.

CONCLUSION

An inverse pattern in IL-2 and IFN-gamma production in PBLs between weeks 20-30 is seen in PTD as compared to patients delivering at term.

The value of quantitative ultrasound tissue characterization of the cervix and rapid fetal fibronectin in predicting preterm delivery

OBJECTIVE

To evaluate clinical risk factors, cervical fetal fibronectin (fFN), cervical length, and mean gray value assessment in predicting of preterm delivery (PTD) in patients with signs and/or symptoms of preterm labor (PTL).

STUDY DESIGN

One hundred and seventeen women with PTL between 24 and 34 weeks of gestation were included. Cervical swabs were tested for fFN using the rapid fFN assay. When 2-dimensional transvaginal ultrasound measurement of cervical length was completed, a region of interest (ROI) of constant size was defined in the midsection of the posterior wall, and the tissue-specific gray scale was determined. The end point were PTDs at <34 and <37 weeks of gestation.

RESULTS

In univariate analysis, the three strongest predictors of spontaneous preterm birth <34 weeks were positive fFN (relative risk [RR] 8.9; 95% confidence interval [CI] 2.6-30.1), cervical length < or =2.5 cm (RR 6.9; 95% CI 1.6-29.7), and a low mean gray value of < or =5.97 (RR 7.9; 95% CI 2.3-27.2). Predictors significantly associated with spontaneous PTD at less than 37 weeks of gestation included previous PTD in multiparas (RR 3.9; 95% CI 1.6-9.5), positive fFN (RR 7.6; 95% CI 3.8-15.3), cervical length < or =2.5 cm (RR 2.6; 95% CI 1.4-5.1) and a low gray scale value of < or =6.54 (RR 4.5; 95% CI 2.3-8.9). In the final regression models used to predict spontaneous PTD <34 weeks and <37 weeks of gestation, both a positive fetal fibronectin (odds ratio [OR] 13.4; 95% CI, 2.5-72.1, P=0.003 vs. OR, 17.3; 95% CI 4.9-61.8, P<0.001) and a low gray scale value (OR 6.3 95% CI 1.3-29.4, P=0.02 vs. OR, 7.1; 95% CI 2-25.2, P=0.003) remained powerful predictors. The RRs of spontaneous PTD <37 weeks has been analyzed by a combination of these significant parameters. Low mean gray value < or =6.54 and negative fFN had a 10.3-fold (95% CI 2-74.5) increased risk of spontaneous preterm birth at <37 weeks. Combination of positive fFN and normal gray level (>6.54), had a higher increase risk of PTD (RR 18.1; 95% CI 4.4-76.7). When both factors were positive, the RR increases to 24.8 (95% CI 6.2-98.7).

CONCLUSIONS

Combined use of rapid fFN and cervical gray value analysis improves the diagnostic efficiency and allows identification of women at risk for preterm delivery and in need for further prophylactic/therapeutic intervention.

Evaluation and validation of a new risk score (CLEOPATRA score) to predict the probability of premature delivery for patients with threatened preterm labor

OBJECTIVE

To develop a clinically useful tool to predict the probability of preterm delivery in patients with threatened preterm labor.

METHODS

One hundred and seventy patients with preterm labor between 24 and 34 weeks of gestation were included. Preterm delivery < 37 weeks of gestation was the main endpoint of the study. The data were randomized and split into an evaluation set (n = 85) and a validation set (n = 85). The evaluation set was subjected to stepwise backward logistic regression analysis to quantify the relative impact of four potential risk factors, including individual patient factors, results of a rapid fetal fibronectin assay, and sonographic measurement of cervical length. Using the constant of the logistic regression analysis and the beta-coefficients for the identified risk factors the individual probability of preterm delivery for each woman of the validation dataset was calculated. The area under a receiver-operating characteristics curve (AUC) was used to evaluate the discriminating power of the score.

RESULTS

The overall rate of preterm delivery was 27.1%. The logistic regression analysis was performed for the potential predictors of spontaneous preterm delivery, identified by univariate analysis. These were positive fetal fibronectin, cervical length, previous preterm delivery and maternal age. Two risk factors were independent predictors of preterm delivery and were included in the CLEOPATRA I (clinical evaluation of preterm delivery and theoretical risk assessment) score: cervical length measurement and previous preterm delivery were associated with a higher risk of preterm delivery (odds ratio, 7.65 and 6.74, respectively). Since fetal fibronectin assay is not available at all institutions worldwide, it was excluded from the initial model. In the CLEOPATRA II model the risk factors fetal fibronectin and previous preterm delivery were associated with higher risk of preterm delivery, with odds ratios of 17.9 and 4.56, respectively. The discrimination power (AUC) obtained from the models were: CLEOPATRA I, 0.69 (95% CI, 0.56-0.82); CLEOPATRA II, 0.81 (95% CI, 0.69-0.93).

CONCLUSION

In symptomatic women the risk for preterm delivery can be predicted best with the CLEOPATRA II score based on fetal fibronectin and previous preterm delivery.

The Heritability of Preterm Delivery

OBJECTIVE

To study the heritability of preterm delivery.

METHODS

Women who delivered a singleton infant at less than 36 weeks of gestation were asked about their family history. Twenty-eight families were identified in which the proband had at least five first- or second-degree relatives with preterm delivery. An extensive genealogy database (GenDB) was constructed using more than 9,000 genealogy sources in the public domain (records before 1929). GenDB documents the relationships between more than 17.5 million ancestors and 3.5 million descendants of approximately 10,000 individuals who moved to Utah in the mid 1800s. This database was searched for the names, birth dates, and birthplaces of the four grandparents for each of the 28 probands. Pairwise coefficients of kinship were determined for the 93 preterm delivery grandparents identified, and for sets of 100 individuals born in the 1920s who were randomly selected from the population database.

RESULTS

Probands had a mean of 3.3 grandparents included in this database. The average coefficient of kinship for controls was 1.5 x 10(6) (standard deviation = 0.6 x 10(6)). This measure agrees with previous calculations for the Utah population. The coefficient of kinship for familial preterm delivery grandparents was more than 50 standard deviations higher (3.4 x 10(5) [P < .001]).

CONCLUSION

This study confirms the familial nature of preterm delivery. On average, gravidae randomly selected from our population are 23rd degree relatives, while these preterm delivery probands are eighth-degree relatives. A genome-wide scan using these affected families is underway.

Assessment of Rapid Fetal Fibronectin in Predicting Preterm Delivery

OBJECTIVE

The aim of this study was to estimate the effectiveness of cervical fetal fibronectin assayed by the rapid fetal fibronectin assay in predicting preterm delivery in patients with signs or symptoms of preterm labor.

METHODS

Patients with preterm labor between 24 and 34 weeks of gestation were included. At the time of speculum examination, fetal fibronectin samples were collected from the cervix. The probe was analyzed for fetal fibronectin using the rapid fetal fibronectin assay. Managing obstetricians were blinded to fetal fibronectin results. Outcome data were collected after delivery.

RESULTS

One hundred seventy patients had fetal fibronectin samples and outcome data. The mean (+/- standard deviation) gestational age at delivery was 38.63 +/- 2.5 weeks among those with negative fetal fibronectin results (n = 124) and 35.71 +/- 3 weeks for those with positive results (n = 46; P < .001). The admission-to-delivery interval was 27.3 days shorter in the group with positive fetal fibronectin results (36.1 +/- 29.9 compared with 63.4 +/- 29.2; P < .001). The rapid fetal fibronectin assays were useful in predicting risk of delivery within 7, 14, or 21 days (sensitivity 81.8%, 87.5%, and 77.3%; specificity 76.7%, 79.2%, and 80.4; positive predictive value 19.6% [9/46], 30.4% [14/46], 37% [17/46]; negative predictive value 98.4% [122/124], 98.4% [122/124], and 96% [119/124], respectively).

CONCLUSION

In a population of patients with signs and symptoms of preterm labor, the presence of cervical fetal fibronectin is effective in predicting risk of delivery within 7, 14, or 21 days. The negative predictive values of fetal fibronectin using the Tli systems compared well with data from previous reports using enzyme-linked immunosorbent assay-based assays.

LEVEL OF EVIDENCE

III.

The changing association between prenatal participation in WIC and birth outcomes in New York City

We analyze the relationship between prenatal WIC participation and birth outcomes in New York City from 1988-2001. The analysis is unique for several reasons. First, we have over 800,000 births to women on Medicaid, the largest sample ever used to analyze prenatal participation in WIC. Second, we focus on measures of fetal growth distinct from preterm birth, since there is little clinical support for a link between nutritional supplementation and premature delivery. Third, we restrict the primary analysis to women on Medicaid who have no previous live births and who initiate prenatal care within the first four months of pregnancy. Our goal is to lessen heterogeneity between WIC and non-WIC participants by limiting the sample to highly motivated women who have no experience with WIC from a previous pregnancy. Fourth, we analyze a large sub-sample of twin deliveries. Multifetal pregnancies increase the risk of anemia and fetal growth retardation and thus may benefit more than singletons from nutritional supplementation. We find no relationship between prenatal WIC participation and measures of fetal growth among singletons. We find a modest pattern of association between WIC and fetal growth among U.S.-born Black twins. Our findings suggest that prenatal participation in WIC has had a minimal effect on adverse birth outcomes in New York City.

Smoking cessation counseling for pregnant women who smoke: scientific basis for practice for AWHONN's SUCCESS project

OBJECTIVES

To review the literature addressing smoking cessation in pregnant women. To develop the project protocol for the Association of Women's Health, Obstetric and Neonatal Nurse's (AWHONN) 6th research-based practice project titled "Setting Universal Cessation Counseling, Education and Screening Standards (SUCCESS): Nursing Care of Pregnant Women Who Smoke." To evaluate the potential of systematic integration of this protocol in primary care settings in which women seek care at the preconception, pregnant, or postpartum stages.

LITERATURE SOURCES

Computerized searches in MEDLINE and CINAHL, as well as references cited in articles reviewed. Key concepts in the searches included low-birth-weight infants and effects of prenatal smoking on the infant and the effects of preconception and prenatal smoking cessation intervention on premature labor and birth weight.

LITERATURE SELECTION

Comprehensive articles, reports, and guidelines relevant to key concepts and published after 1964 with an emphasis on new findings from 1996 through 2002. Ninety-eight citations were identified as useful to this review.

LITERATURE SYNTHESIS

Tobacco use among pregnant women and children's exposure to tobacco use (secondhand smoke) are associated with pregnancy complications such as placental dysfunction (including previa or abruption), preterm labor, premature rupture of membranes, spontaneous abortions, and decreased birth weight and infant stature. Neonates and children who are exposed to secondhand smoke are at increased risk for developing otitis media, asthma, other respiratory disorders later in childhood; dying from sudden infant death syndrome; and learning disorders. The "5 A's" intervention and use of descriptive statements for smoking status assessment were synthesized into the SUCCESS project protocol for AWHONN's 6th research-based practice project.

CONCLUSIONS

The literature review generated evidence that brief, office-based assessment, client-specific tobacco counseling, skill development, and support programs serve as an effective practice guideline for clinicians. Implementation and evaluation of the guideline is under way at a total of 13 sites in the United States and Canada.

Reducing the risk for preterm birth: evidence and implications for neonatal nurses

The incidence of preterm birth has been slowly rising despite advances in obstetric health care. Neonatal nurses have ongoing contact with women who have had a preterm birth and, thus, who are at high risk to have another preterm birth. This article discusses current evidence about reducing risk for preterm birth. Although preterm birth cannot always be prevented, preconception care can help identify and modify maternal risk and promote optimal health before conception. Quality prenatal care, as defined by the Institute of Medicine, consists of continuing risk assessment, health promotion, and interventions to modify medical and psychosocial risk. When these 3 components are consistently applied, they may confer some protection against preterm birth. Women at highest risk for preterm birth need to seek prenatal care from an expert in maternal-fetal medicine. Women also need to learn about the common, subtle signs of preterm labor so they can recognize symptoms and quickly seek treatment. Neonatal nurses can provide critical information and anticipatory guidance to women at risk for preterm birth so they can make sound decisions about future pregnancies.

Psychosocial pathways to prematurity: changing our thinking toward a lifecourse and community approach

The purpose of this article is to explore the psychosocial antecedents of prematurity. Emphasis is on conceptual areas and supporting literature for (a) the contexts in which prematurity occurs and the diversity of women's experiences; (b) a lifecourse approach to prematurity that highlights allostatic load and the accumulation of trauma and loss in possible prematurity pathways; and (c) diverse psychosocial/biological pathways and mechanisms of prematurity processes. Pathways examining psychosocial and prematurity connections will be explicated, including antecedents and outcomes other than stress proneness and vulnerability. Implications for research are logically derived from a focus on the impact of social context on individual outcomes through multilevel models and methods. Clinical implications are derived from the social contexts, lifecourse, and multiple pathways focus of the article and include increasing social cohesion in communities, population health strategies, particular psychosocial interventions, and attentive listening.

Implementing evidence-based practice: reducing risk for low birth weight through pregnancy smoking cessation

In 1989, the Association of Women's Health, Obstetric and Neonatal Nurses (AWHONN) developed a research utilization program to integrate evidence into practice areas where there were large discrepancies between research evidence and clinical practice. The current program, renamed Research-Based Practice (RBP), uses translational research methods to build from evidence such as that in the Cochrane database and to create protocols for integration of research directly into clinical practice. This article describes the development of the sixth project (RBP6), in which an evidence-based protocol to address smoking in pregnancy was integrated into clinical practice. The protocol includes screening women using descriptive statements and integrates the 5 As (ask, advise, assess, assist, arrange) into prenatal and postpartum care at every visit. By integrating smoking cessation counseling into care, nurses may reduce the risk of low birth weight among pregnant women in both the United States and Canada.

Evaluation of quantitative ultrasound tissue characterization of the cervix and cervical length in the prediction of premature delivery for patients with spontaneous preterm labor

OBJECTIVE

This study was to evaluate the predictive value of the uterine cervix tissue with the use of quantitative ultrasound gray level analysis for preterm delivery.

STUDY DESIGN

Sixty-eight patients with preterm labor between 20 and 35 weeks of gestation were included. When two-dimensional transvaginal ultrasound measurement of cervical length was completed, a region of interest of constant size was defined in the midsection of the posterior wall, and the tissue-specific gray scale was determined. Preterm delivery of <37 weeks of gestation was sought.

RESULTS

Twenty-eight patients (41.2%) were delivered preterm. The risk for preterm delivery was increased significantly in patients with cervical length of </=2.5 cm (odds ratio, 7.67; 95% CI, 2.4-24.45), with Bishop score of >/=4 (odds ratio, 3.44; 95% CI, 1.21-9.75), and with decreased mean gray scale value (odds ratio, 12.13; 95% CI, 3.69-39.88). Parity and uterine contractions were not significant as predictors for preterm delivery, although the risk for preterm delivery increased with higher parity (odds ratio, 1.8; 95% CI, 0.68-4.79). The risk for preterm delivery remained nearly the same by uterine contractions (odds ratio, 0.92; 95% CI, 0.28-3.01). A mean scale value of </=6.54 had the best cutoff value for the prediction of preterm delivery. For preterm delivery, a mean gray value </=6.54 had a sensitivity of 82.1%, a specificity of 72.5%, a positive predictive value of 67.6%, and a negative predictive value 85.3%. Multiple logistic regression analysis indicated that, even when other variables are considered simultaneously, the mean gray scale value is the single best predictor of preterm delivery.

CONCLUSION

Quantitative ultrasound tissue characterization of the uterine cervix predicts premature delivery and provides additional information in the prediction of potential premature delivery.

Spontaneous preterm delivery in the type 1 diabetic pregnancy: the role of glycemic control

OBJECTIVE

To determine the role of glycemic control in spontaneous preterm delivery in type 1 diabetic women.

METHODS

A secondary analysis of data from women enrolled in the Diabetes in Pregnancy Program prior to 20 weeks was performed. Multiple logistic regression was used to analyze the association between glycohemoglobin A1 in women with spontaneous preterm delivery (n = 53) and women who delivered at term (n = 200). Maternal demographics and obstetric outcomes were also compared between the groups.

RESULTS

Glycohemoglobin A1 levels were higher in the spontaneous preterm delivery group than the term group throughout pregnancy, reaching statistical significance after the first trimester. The last glycohemoglobin A1 prior to delivery was 8.1% in the spontaneous preterm delivery group and 7.4% in the term group (p = 0.002). Using multiple logistic regression, each 1% increase in glycohemoglobin A1 increased the risk of spontaneous preterm delivery by 37%.

CONCLUSION

Poor glycemic control is associated with an increased risk of spontaneous preterm delivery, suggesting that strict glycemic control may reduce the rate of preterm delivery in these women.

Dysphoria among high-risk pregnant hospitalized women on bed rest: a longitudinal study

BACKGROUND

While approximately 700,000 women experience pregnancy complications and are treated with bed rest in the hospital each year, little is known about negative affect in these women.

OBJECTIVES

The study purpose was to describe dysphoria, a composite of symptoms of negative affect across the antepartum and postpartum and to identify the relationship between dysphoria and the length of pre-admission home bed rest, hospital bed rest, and maternal and fetal/neonatal indices of risk.

METHODS

The convenience sample for this longitudinal repeated measures study consisted of 63 high-risk pregnant women admitted on antepartum bed rest to one of three university-affiliated hospitals. Women were included if they were diagnosed with (a) preterm labor, (b) premature rupture of membranes, (c) incompetent cervix, (d) placenta previa, (e) placental abruption or multiple gestation, and (f) did not have a psychiatric disorder. The Multiple Affect Adjective Checklist-Revised (MAACL-R) was used to assess dysphoria. Obstetric risk status was assessed by both the Hobel and Creasy Risk Assessment tools.

RESULTS

Dysphoria was highest upon hospital admission and decreased significantly across time (F (5) = 23.58, p <.001). Positive Affect-Sensation Seeking significantly increased across time (F (5) = 53.16, p <.001). Dysphoria scores were significantly greater for those with highest Hobel obstetric risk scores (F (1, 60) = 4.53, p =.037). Antepartum dysphoria was not correlated with gestational age upon hospital admission, length of bed rest, or Creasy risk status. However, gestational age at birth was significantly correlated with postpartum dysphoria.

DISCUSSION

The stimulus for antepartum dysphoria is unclear. However, postpartum dysphoria appears to be related to indicators of the infant's state of health at birth.

Phenotypic and metabolic characteristics of maternal monocytes and granulocytes in preterm labor with intact membranes

OBJECTIVE

Experimental and clinical studies support a role for the fetus in the control of the onset of labor. Fetal systemic inflammation, but not a maternal inflammatory response, has been linked to the onset of preterm labor and delivery on the basis of the determination of inflammatory cytokines in fetal and maternal blood. We propose that parturition requires fetomaternal cooperation and that inflammation is an integral part of the parturitional process. This study used flow cytometry, a sensitive technique for the detection of intravascular inflammation, to assess whether maternal inflammation is present in preterm labor.

STUDY DESIGN

A prospective cross-sectional study was performed including patients with preterm labor (n = 55) and women with normal pregnancy (n = 50). Intravascular inflammation was studied by using flow cytometry. Maternal blood was assayed to determine granulocyte and monocyte phenotype by using monoclonal antibodies, which included the following cluster of differentiation (CD) markers: CD11b, CD14, CD15, CD16, CD18, CD49d, CD62L, CD64, CD66b, and HLA-DR. Oxidative burst and generation of basal intracellular oxygen radical species were assessed. Statistical analysis was conducted with the use of nonparametric methods. A P value of <.01 was considered statistically significant.

RESULTS

Preterm labor was associated with a significant increase in the median mean channel brightness of CD11b, CD15, and CD66b on granulocytes and median mean channel brightness of CD11b and CD15 on monocytes. The ratio of oxidative burst over basal intracellular oxygen radical species in both granulocytes and monocytes was increased in preterm labor (P <. 01).

CONCLUSION

Preterm labor with intact membranes is associated with phenotypic and metabolic changes of maternal granulocytes and monocytes.

Risk stratification and pathological mechanisms in preterm delivery

The delivery of infants before 37 weeks gestation is a leading cause of perinatal mortality and morbidity in the United States. Traditional methods of predicting women at risk relying on obstetric history or premonitory symptoms (detected clinically or by tocodynamometry) are neither sensitive nor specific. Recent approaches to predicting preterm delivery have included sonographic measurement of cervical length and various biochemical assays. Although more sensitive than traditional methods, none of these alone exhibits sufficient accuracy to warrant widespread use. We contend that the failure of current approaches to predicting preterm delivery reflects an inadequate understanding of the underlying pathogenesis. Clinical and experimental evidence support the concept that most cases of preterm delivery reflect four pathogenic processes, which share a common final biological pathway leading to uterine contractions and cervical changes with or without premature rupture of membranes. These pathogeneses are: (1) activation of the maternal or fetal hypothalamic-pituitary-adrenal axis; (2) decidual-chorioamniotic or systemic inflammation; (3) decidual haemorrhage (i.e. abruption); and (4) pathological distention of the uterus. Our research seeks to combine the most useful biophysical and biochemical markers of such processes with optimal clinical and epidemiological predictors into a composite, easily applied risk tool. This integrated approach has the potential to identify at-risk asymptomatic patients with high sensitivity, specificity, and positive and negative predictive values, and also to ascertain underlying pathogenic processes that can lead to targeted therapy. To accomplish these goals, we employ logistic regression and artificial neural network models to assess and apply the appropriate weight to markers associated with each of the above pathogenic pathways, in addition to markers of the final common pathway leading to fetal membrane rupture, cervical extracellular matrix degradation, and myometrial activation. By combining these markers, we expect ultimately to produce a predictive model that is more robust than any existing method, and that identifies the relative contribution of each pathogenic process. Further analysis of this model using a neural network will enable us to identify asymptomatic patients destined to deliver preterm with high sensitivity, specificity, positive and negative predictive values, and to assess the relative contribution of each of the four distinct pathogeneses to this preterm delivery risk.

Risk factors for intraventricular hemorrhage in a birth cohort of 3721 premature infants

AIMS

In our study we determined possible risk factors for intraventricular hemorrhage grade III to IV (IVH) based on a regional German neonatal data base and tried to build a logistic-regression model to predict the risk of IVH according to gestational age.

MATERIALS

We identified 3721 premature infants, 22 to 36 completed weeks of gestational age, born from 1994 through 1997. 136 (3.7%) IVH were diagnosed sonographically. 60 (44%) infants with IVH died. We examined the following variables as risk factors for IVH: gestational age, sex, blood pH of 7.2 or less, body temperature of 35 degrees C or less, multiple birth, small-for-gestational age, intubation after birth, transport to another hospital.

RESULTS

In the full logistic regression model sex, blood pH of 7.2 or less, multiple birth, and small-for-gestational age were not associated with a significant risk of IVH. Body temperature of 35 degrees C or less was associated with an increased risk of IVH (adjusted odds ratio, 1.92; 95% confidence interval, 1.09 to 3.40). Intubation after birth increased the risk of IVH in neonates under 28 weeks of gestational age (OR, 3.72; 95% CI, 1.65 to 8.38) only to a moderate extent, but significantly in neonates 32 to 36 weeks of gestational age (OR, 16.51; 95% CI: 7.35 to 36.18). The risk of IVH was mainly related to gestational age. Neonates delivered before 28 weeks of gestation (OR, 75.72; 95% CI, 46.14 to 124.30) faced the highest risk of IVH. Transport to another hospital was connected with an increased risk of IVH regardless of gestational age (adjusted OR, 1.95; 95% CI, 1.07 to 2.56).

CONCLUSION

The frequency of IVH could be reduced significantly, if extremely premature infants, the vast majority of patients suffering from IVH, did not have to be transferred postnatally to another hospital.

Prevention of premature birth: do pediatricians have a role?

The rate of prematurity in the United States has increased over the past 15 years despite a reduction in overall infant mortality and birth weight-specific mortality. The major factors contributing to premature birth exist before pregnancy and therefore will require intervention strategies in the pediatric patient. The high-risk factors include young age at conception (16 years), use of illicit drugs and smoking, poor nutritional status, and certain vaginal infections. Pediatric intervention strategies should include sociologic as well as health education stressing heightened self-esteem and communication skills, avoidance of pregnancy and unprotected sexual activity, avoidance of smoking and drug use, and promotion of a good nutritional status.

Morphology assessed by transvaginal ultrasonography differs in patients in preterm labor with vs. without bacterial vaginosis

OBJECTIVE

To determine whether cervical morphology in preterm labor patients differs in the presence or absence of bacterial vaginosis.

DESIGN

Observational study.

SUBJECTS

One hundred and twelve consecutive patients with objectively confirmed preterm labor admitted to a tertiary care centre were included in the study. Patients with placenta previa, active uterine bleeding or indication for an immediate delivery (e.g. severe pre-eclampsia or suspected fetal asphyxia), or severe fetal anomalies were excluded.

METHODS

Transvaginal ultrasonography was used to measure cervical length and internal os width. Bacterial vaginosis was diagnosed by Gram stain of a vaginal smear.

RESULTS

A total of 36 patients (32%) had bacterial vaginosis. Cervical length in this group was shorter than in patients with normal flora (mean 20.4 +/- 7.2 mm vs. 26.4 +/- 6.7 mm; P = 0.0002), and more patients with bacterial vaginosis had a dilated internal cervical os > or = 5 mm (67% vs. 30%, P = 0.001). There were no significant differences, however, in preterm delivery rate and birth weight between the two groups; the overall preterm delivery rate was 40%. A cervical length < 25 mm was predictive of preterm delivery (P = 0.001, RR 4.2, 95% CI 1.8-9.7).

CONCLUSIONS

These data suggest that cervical change in preterm labor is more pronounced in patients with bacterial vaginosis but without a concomitant increase in the risk for preterm delivery. Despite this association, the cervical length measured by transvaginal ultrasonography alone is a useful predictor of preterm delivery, independent of the presence or absence of bacterial vaginosis.

The cervix as a predictor of preterm delivery in 'at-risk' women

OBJECTIVE

To examine the relationship between ultrasound-determined cervical status and pregnancy outcome in women 'at-risk' of spontaneous preterm delivery.

DESIGN

A prospective cohort study of 120 pregnant women considered to be 'at-risk' of spontaneous preterm delivery by their clinician. Transvaginal ultrasound of the cervix was used to assess overall cervical length, closed endocervical canal length, diameter and internal os dilatation in the second trimester. The main outcome measure was occurrence of spontaneous preterm birth (< 34 and < 37 weeks of gestation).

RESULTS

The overall preterm delivery rate (< 37 weeks gestation) in these women was 35% (n = 42) with 20% (n = 24) delivering < 34 weeks gestation. Of the 71 women with a normal cervix, 8 (11%) delivered < 34 weeks, whereas of the 49 women with an abnormal cervix, 16 (33%) delivered < 34 weeks (RR 2.90; 95% CI 1.35-6.24). Using linear regression, closed endocervical canal length of < 21 mm before 20 weeks is associated with delivery < 34 weeks in 95% of women, and with delivery < 37 weeks in 95% of women if the canal length is < 33 mm. Logistic regression showed closed endocervical canal length to be the only significant factor in those women who delivered < 34 weeks after controlling for possible confounders.

CONCLUSIONS

A strong relationship is demonstrated between cervical status and pregnancy outcome, particularly the cervical findings before 20 and 24 weeks of gestation. The length of the closed portion of the endocervical canal is the best predictor. A beneficial effect of this approach to 'at-risk' women is the reduction in unnecessary interventions in those with normal cervical findings.

Growth patterns and nutritional factors associated with increased head circumference at 18 months in normally developing, low-birth-weight infants

OBJECTIVE

To identify patterns of growth, nutrition practices, and feeding behaviors associated with normal Denver II developmental screening results at 18 months of age.

DESIGN

A retrospective review of hospital medical charts was conducted to collect discharge diagnosis and dietary data. Developmental clinic charts were reviewed to collect growth and diet data, Denver II results, and medical data from 4-, 9-, and 18-month visits.

SUBJECTS/SETTING

Twenty-eight children were identified from a review of developmental clinic records in a midwestern children's hospital. Criteria were single or twin birth, birth weight of 2,000 g or less, follow up at the hospital developmental clinic, and completion of 3 screening visits.

STATISTICAL ANALYSES PERFORMED

National standards were used to calculate z scores. Patterns of growth were analyzed using analysis of variance. Stepwise forward linear regression analysis was done to construct a model predicting head circumference at 18 months of age.

RESULTS

Significant catch-up growth (P = .0006) occurred as length z score increased from -0.87 at 4 months of age to -0.45 at 18 months. A regression model predicting head circumference at age 18 months was developed that included nutrition and growth variables such as head circumference at 9 months, type of parenteral amino acids administered in the hospital, z score of weight at 4 months' adjusted age, and time of first enteral feeding.

APPLICATIONS

Interventions designed to support breast-feeding in the hospital and at home are indicated as is increased emphasis on monitoring growth. Delays in growth need to be treated aggressively; for example, nutrition interventions should begin by the age of 4 months if weight gain is not appropriate.

Vaginitis, cervicitis, and cervical length in pregnancy

OBJECTIVE

We sought to determine the possible association among vaginitis, cervicitis, and cervical length in pregnancy.

STUDY DESIGN

Primigravid volunteers, between 20 and 36 weeks' gestation (n = 210), were examined. Vaginitis was diagnosed by pH determination and wet mount smear, cervicitis was diagnosed by cervicography, and cervical length was diagnosed by vaginal ultrasonographic measurement. Patients with both vaginitis and cervicitis (n = 70) were compared with those without any trace of infection (n = 23). The remainder (n = 117) had variable degrees of infection and were excluded.

RESULTS

The mean gestational age was 28.3 weeks. No significant association was found among vaginitis, cervicitis, and cervical length. In the infection group (n = 70), however, a significant association between an elevated vaginal pH (>5) and a shortened cervical length (r = 0.29) was noted.

CONCLUSION

No significant association exists among vaginitis, cervicitis, and cervical length, but in patients with clinical signs of infection, an elevated pH appears to be associated with a decreased cervical length.

The influence of gestational age and smoking habits on the risk of subsequent preterm deliveries

BACKGROUND

Previous preterm delivery and maternal smoking are associated with increased risks of preterm delivery. It is not known whether gestational age at the time of a preterm delivery is correlated with gestational age in successive preterm deliveries and whether changes in smoking habits influence the subsequent risk of preterm delivery.

METHODS

We studied the associations among smoking habits, previous very preterm or moderately preterm delivery (before 32 weeks and at 32 to 36 weeks, respectively), and the risk of a subsequent very preterm or moderately preterm delivery in a population-based cohort of 243,858 women in Sweden between 1983 and 1993. The results were adjusted for covariates known to be associated with preterm delivery.

RESULTS

The odds ratios for very or moderately preterm delivery in a subsequent pregnancy among women with a previous very preterm delivery, as compared with women who had a previous term delivery, were 12.4 (95 percent confidence interval, 9.1 to 17.0) and 7.1 (95 percent confidence interval, 6.0 to 8.4), respectively. Among women with a previous moderately preterm delivery, the corresponding odds ratios were 2.3 (95 percent confidence interval, 1.9 to 3.0) and 5.9 (95 percent confidence interval, 5.5 to 6.3), respectively. The odds ratios for a very preterm second delivery among the women who smoked 1 to 9 cigarettes per day and those who smoked 10 or more cigarettes per day, as compared with nonsmokers, were 1.4 (95 percent confidence interval, 1.1 to 1.7) and 1.6 (95 percent confidence interval, 1.3 to 2.0), respectively. The corresponding odds ratios for moderate preterm delivery were 1.3 (95% confidence interval, 1.2 to 1.4) and 1.5 (95 percent confidence interval, 1.4 to 1.6). The women who quit smoking between pregnancies were not at increased risk for very or moderately preterm delivery, whereas the women who started to smoke in the second pregnancy had the same risk as those who continued to smoke.

CONCLUSIONS

The risk of a very preterm delivery in successive pregnancies is increased primarily among women with a previous very preterm delivery. Changes in smoking habits influence the risk of preterm delivery as well.

Genetic factors in preterm delivery

Tens of thousands of children deliver before they are full term each year. Although many social, environmental, and medical risk factors have been suggested, the etiology of a large percentage of preterm labor cases is still unknown. It has been noted for many years that preterm delivery is a condition that runs in families. Evidence concerning its aggregation among families, the recurrent nature of preterm labor, and its differing prevalence between races has led to the suggestion of a genetic cause for preterm delivery. There have been few formal studies to investigate this hypothesis. We suggest that modern molecular biology approaches can reveal the part that genes play in preterm delivery.