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PubMed2005

Maternal smoking and causes of very preterm birth.

BACKGROUND: Smoking increases the risk of preterm birth. The present study was made to elucidate the relation of smoking to causes of very preterm birth. METHODS: In a case-control study on all very preterm births in two regions of Stockholm 1988-1992, prospectively collected data were extracted from antenatal and delivery records on smoking, other maternal characteristics, pregnancy complications, and causes of preterm birth. Cases were live single births with a gestational age of < or =32 weeks and 0 days, and controls were live singletons delivered at 37 weeks or later (n = 295, respectively). Odds ratios (ORs) with 95% confidence intervals (CIs) were calculated with logistic regression. RESULTS: Compared with non-smokers, adjusted ORs of very preterm birth among moderate smokers (1-9 cigarettes per day) and heavy smokers (> or =10 cigarettes per day) were 1.4 (95% CI 0.8-2.4) and 2.9 (95% CI 1.5-5.7), respectively. Compared with non-smokers, risk of preterm labor was increased among moderate and heavy smokers [ORs 1.9 (95% CI 1.0-3.6) and 2.6 (95% CI 1.1-1.6), respectively]. These risks remained essentially unchanged in women without an identifiable cause of preterm labor ('idiopathic preterm labor'). Smoking was also associated with dose-dependent increases in risks of preterm birth due to preterm premature rupture of membranes and late pregnancy bleedings. There was no association between smoking and risk of very preterm birth caused by hypertensive diseases. CONCLUSIONS: Smoking increases the risk of very preterm birth caused by preterm labor (including idiopathic preterm labor), preterm premature rupture of membranes, and late pregnancy bleedings.

Adult↗

PubMed2000

Early pregnancy predictors of preterm birth: the role of a prolonged menstruation-conception interval.

OBJECTIVE: To study early pregnancy characteristics as possible risk factors associated with preterm birth. DESIGN: Retrospective analysis of prospectively collected maternity data. POPULATION: 21,069 singleton deliveries with record of a specified last menstrual period and a midtrimester dating scan. SETTING: Catchment area of tertiary centre serving a general maternity population. METHODS: Univariate and multivariate analysis. Variables included: maternal age; height; weight at first visit; parity; ethnic group; cigarette smoking and alcohol consumption recorded in early pregnancy; history of abortion; history of preterm birth; and discrepancy between menstrual dates and ultrasound dates. MAIN OUTCOME MEASURES: Adjusted odds ratios for factors associated with preterm birth, stratified according to parity (nulliparae vs multiparae) and gestational age (early preterm, 24-33 weeks; late preterm, 34-36 weeks; all preterm, < 37 weeks). Population attributable risk (aetiologic fraction) of the significant variables for preterm birth. RESULTS: The overall preterm (< 37 weeks) delivery rate according to scan dates was 7 x 0%. Preterm birth was associated with young (< 20 years), short (< or = 155 cm) and underweight (< or = 52 kg) mothers, non-Europeans, cigarette smokers, previous abortion or previous preterm delivery, and a prolonged menstruation-conception interval. Preterm births which followed the spontaneous onset of labour (72%) had results which were similar to the overall group, while there were too few iatrogenic preterm deliveries for separate analysis. Logistic regression showed that associations varied in different parity and gestational age groups. For nulliparae, smoking was not associated with preterm birth, but it was strongly associated with multiparous women (adjusted OR 1 x 8, 95% CI 1 x 6-2 x 1). A past history of premature delivery had the highest risk for birth before 34 weeks in the index pregnancy (adjusted OR 5 x 1, 95% CI 3 x 4-7 x 6). A discrepancy between menstrual and scan dates of greater than +7 days, suggestive of a prolonged interval between last menstruation and conception, was present in 23 x 3% of all pregnancies, and was associated with an increased risk of preterm delivery in all gestational age categories for nulliparae (adjusted OR 1 x 5, 95% CI 1 x 3-1 x 8) and multiparae (adjusted OR 1 x 9, 95% CI 1 x 6-2 x 2). Because of its high prevalence, this variable constituted a relatively high population-attributable risk for premature birth for both nulliparae (10 x 7%) and multiparae (16 x 6%). CONCLUSIONS: A discrepancy of more than +7 days between menstrual and scan dates, indicating a prolonged interval between last menstruation and conception, is a significant predictor of preterm birth. This effect is independent of other factors such as maternal age, height, weight and smoking which are also associated with prematurity. In a maternity population with ultrasound scan dates and recorded last menstrual period, this variable can be easily calculated and used as a marker for increased surveillance.

Analysis of Variance↗

PubMed2005

Previous induced abortions and the risk of very preterm delivery: results of the EPIPAGE study.

OBJECTIVES: To evaluate the risk of very preterm birth (22-32 weeks of gestation) associated with previous induced abortion according to the complications leading to very preterm delivery in singletons. DESIGN: Multicentre, case-control study (the French EPIPAGE study). SETTING: Regionally defined population of births in France. SAMPLE: The sample consisted of 1943 very preterm live-born singletons (< 33 weeks of gestation), 276 moderate preterm live-born singletons (33-34 weeks) and 618 unmatched full-term controls (39-40 weeks). METHODS: Data from the EPIPAGE study were analysed using polytomous logistic regression models to control for social and demographic characteristics, lifestyle habits during pregnancy and obstetric history. The main mechanisms of preterm delivery were classified as gestational hypertension, antepartum haemorrhage, fetal growth restriction, premature rupture of membranes, idiopathic preterm labor and other causes. MAIN OUTCOME MEASURES: Odds ratios for very preterm birth by gestational age and by pregnancy complications leading to preterm delivery associated with a history of induced abortion. RESULTS: Women with a history of induced abortion were at higher risk of very preterm delivery than those with no such history (OR + 1.5, 95% CI 1.1-2.0); the risk was even higher for extremely preterm deliveries (< 28 weeks). The association between previous induced abortion and very preterm delivery varied according to the main complications leading to very preterm delivery. A history of induced abortion was associated with an increased risk of premature rupture of the membranes, antepartum haemorrhage (not in association with hypertension) and idiopathic spontaneous preterm labour that occur at very small gestational ages (< 28 weeks). Conversely, no association was found between induced abortion and very preterm delivery due to hypertension. CONCLUSION: Previous induced abortion was associated with an increased risk of very preterm delivery. The strength of the association increased with decreasing gestational age.

Abortion, Induced↗

PubMed2005

Controversies in diagnosis of preterm labour.

Despite scientific advances, efforts to prevent preterm birth can be disappointing. Obstetric care must focus on strategies to improve the outcome of preterm infants. The major goal is to delay preterm birth long enough to allow the transfer of women about to deliver preterm to a facility with a neonatal intensive care unit and to administer corticosteroids to enhance fetal lung maturation. A prerequisite for the success of this strategy is the reliable identification of women who will give birth preterm. Although symptoms of preterm labour strongly suggest preterm birth, contractions-even if combined with cervical effacement and dilation-do not reliably predict preterm birth. The diagnosis of true preterm labour that will eventually lead to preterm birth has been facilitated by the use of transvaginal cervical ultrasonography and by the detection of fetal fibronectin (FFN) in cervicovaginal secretions. The main clinical value of these tests is that preterm birth is very unlikely if the results of both tests are negative. This may help to avoid unnecessary transfer, hospitalisation and treatment of women with false preterm labour. The detection of phosphorylated insulin-like growth factor binding protein-1 in cervicovaginal secretions, or elevated levels of inflammatory markers, like interleukin-6, interleukin-8 and tumour necrosis factor-alpha (TNF-alpha), also predict preterm birth in symptomatic women. These markers, however, are not routinely used to predict preterm birth in women with symptoms of preterm labour.

Female↗

PubMed2005

Severe umbilical cord acidemia and neurological outcome in preterm and full-term neonates.

BACKGROUND: Severe intrauterine hypoxia-ischemia and acidemia may lead to a disturbed neurodevelopment. OBJECTIVES: To study the effects of acidemia at birth on neurodevelopment in preterm and full-term neonates. SUBJECTS AND METHODS: Short- and long-term outcome were studied retrospectively in 44 inborn preterms and 95 full-terms with severe acidemia at birth defined as a pH of the umbilical artery <7.00. Outcome was compared with 67 preterm and 90 full-term non-acidemic neonates (pH>7.15). Intraventricular hemorrhage (preterms) or seizures (both preterms and full-terms) were considered an adverse short-term outcome. Neonatal death, cerebral palsy or neurodevelopmental delay were considered an adverse long-term outcome. RESULTS: Severe intraventricular hemorrhage (IVH) occurred in 5 of the 44 (11%) acidemic preterms and in none of the 67 (0%) non-acidemic preterms (p<0.01). Seizures were observed in 9 of the 44 (20%) and 11 of the 95 (12%) acidemic preterms and full-terms, respectively, and in none of the 67 (0%) and 1 of the 90 (1%) non-acidemic preterms and full-terms, respectively (p<0.001 for preterms, p<0.01 for full-terms). Nine preterms (6 acidemic, 3 non-acidemic) and 2 full-terms (both acidemic) died in the neonatal period. Adverse long-term outcome occurred in 32% of the acidemic preterms, in 21% of the non-acidemic preterms, in 7% of the acidemic full-terms and in 7% of the non-acidemic full-terms. CONCLUSIONS: Acidemia at birth increased the occurrence of severe IVH in preterm neonates and seizures in both preterm and full-term neonates. However, no significant effect of acidemia on long-term outcome could be demonstrated.

Acidosis↗

PubMed1995

Fetal growth and the etiology of preterm delivery.

OBJECTIVE: To confirm that preterm delivery is associated with fetal growth restriction (FGR), and to determine if the various etiologies of preterm delivery are associated with the same degree and type of FGR. METHODS: Two hundred ninety young, primarily minority gravidas who had routine initial ultrasound examinations also had subsequent ultrasound examinations at 32 weeks' gestation. Fetal growth characteristics were compared between preterm (less than 37 weeks' gestation) and term deliveries, and among preterm deliveries with medical or obstetric indications, premature rupture of membranes (PROM), and spontaneous preterm labor. RESULTS: Forty-six infants (15.9%) were born preterm. At 32 weeks' gestation, all fetuses later delivered preterm were already smaller than fetuses later delivered at term (P < .05) for all dimensions: head circumference (HC), abdominal circumference (AC), biparietal diameter (BPD), and femur length (FL). However, after stratifying by cause of preterm delivery for those fetuses later delivered for medical or obstetric indications, we found that only AC was decreased (P < .01) and that the HC-AC ratio was elevated (asymmetric FGR). Neonates delivered after unsuccessfully treated PROM or preterm labor were symmetrically smaller in all characteristics (HC, AC, BPD, and FL). CONCLUSION: By 32 weeks' gestation, fetuses later delivered preterm are already significantly smaller than fetuses later delivered at term. However, when stratified by the etiology of preterm delivery, infants delivered preterm for medical or obstetric indications had asymmetric growth patterns, which suggests a growth failure late in pregnancy. Infants delivered preterm after PROM or after failed or no tocolysis for spontaneous preterm labor were proportionately smaller, implying an overall slowing of growth that may originate early in pregnancy and possibly demonstrate a more chronic stress.

Adult↗

PubMed1995

The origin and outcome of preterm twin pregnancies.

OBJECTIVE: To define the etiology of preterm twin births and determine the contribution of twin births to preterm birth and related morbidity and mortality. METHODS: The March of Dimes Multicenter Prematurity and Prevention Study included a total of 33,873 women who delivered between 1982-1986, 432 (1.3%) of which delivered twins. Women were classified by reason for preterm birth and ethnicity. Neonates were classified as to stillbirth, neonatal death, and various short-term morbidities. A second data set from one center consisted of infants who weighed 1000 g or less, were born between 1979-1991, and survived to 1 year of age (n = 386, 15% twins); this was used to determine if twins and singletons born at comparable gestational ages have a similar risk for major developmental handicaps. RESULTS: Of the deliveries in the data set, 54% of twins were preterm compared with 9.6% among singletons. Of those born preterm, twins were born at a significantly earlier gestational age than were singletons. Only 2.6% of all neonates born were twins, but they represented 12.2% of all preterm infants, 15.4% of all neonatal deaths, and 9.5% of all fetal deaths. Spontaneous labor accounted for 54% of twin births, premature rupture of membranes accounted for 22%, and indicated deliveries accounted for 23%. Of the indicated preterm births in twins, 44% were due to maternal hypertension, 33% to fetal distress or fetal growth restriction, 9% to placental abruption, and 7% to fetal death. Comparing infants of similar gestational age, twins weighed less, but had a mortality equivalent to that of singletons after 29 weeks. Between 26-28 weeks' gestation, the risk of mortality for twins versus singletons was 1.6 (95% confidence interval 1.1-2.5). Preterm twins did not have significantly more respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, or other short-term morbidity than did preterm singletons. Twins who weighed 500-1000 g and survived to 1 year had a 25% rate of major developmental handicaps. However, when gestational age was controlled, the rate of major handicaps was not higher in twins than in singletons. CONCLUSIONS: Twins accounted for a disproportional amount of preterm birth and associated morbidity and mortality. Also, when preterm twins were compared with preterm singletons and corrected for their gestational ages, the rates of morbidity were similar. Preterm twins weighing less than 1000 g did not have an increased prevalence of major handicaps at 1 year of age compared with preterm singletons.

Birth Weight↗

PubMed1995

The effectiveness of preterm-birth prevention educational programs for high-risk women: a meta-analysis.

OBJECTIVE: To evaluate whether preterm-birth prevention educational programs are effective at reducing neonatal mortality, low birth weight (LBW), and preterm delivery. DATA SOURCES: A MEDLINE literature search of English-language studies was performed, supplemented by a bibliography search of original research and review articles to locate studies assessing preterm-birth prevention programs. METHOD OF STUDY SELECTION: We identified 31 studies that reported results from trials evaluating preterm-birth prevention programs. From this group, only the six randomized controlled trials evaluating preterm-birth prevention education programs satisfied criteria of homogeneity to be included in a meta-analysis. One of these six studies was a subset of another study and was excluded except when reporting outcomes that were not included in the larger report. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers assessed study methodology and identified the following outcomes: LBW frequency, preterm birth frequency, neonatal survival, birth weight, gestational age at delivery, and preterm labor diagnosis rates. When data were combined using meta-analytic techniques, no significant benefits were found for preterm-birth education programs in preventing neonatal death (cumulative relative risk [RR] 1.00, 95% confidence interval [CI] 0.99-1.01), LBW rates (RR 0.99, 95% CI 0.88-1.11), or preterm delivery rates (RR 1.08, 95% CI 0.92-1.27). The only statistically significant effect of preterm birth education programs appears to be an increase in the frequency at which preterm labor is diagnosed (RR 1.71, 95% CI 1.41-2.08). CONCLUSION: Preterm-birth prevention educational programs appear to have little benefit in reducing preterm birth and may result in an increased rate of diagnosis of preterm labor.

Female↗

PubMed1999

The tumor necrosis factor alpha and its soluble receptor profile in term and preterm parturition.

OBJECTIVE: The common terminal pathway of parturition describes the anatomic, biochemical, endocrine, and clinical events present in the fetus and mother in both term and preterm labor. Labor at term is thought to result from physiologic activation of this pathway, whereas preterm labor is the result of pathologic activating events. The purpose of this study was to determine whether physiologic and pathologic activation could be discerned by the analysis of a cytokine-receptor signaling system. Tumor necrosis factor alpha and its soluble receptors were used as probes because of their pivotal role in the regulation of several processes activated during parturition. Soluble receptors are thought to buffer the biologic and potentially deleterious effects of tumor necrosis factor alpha in pathologic conditions. STUDY DESIGN: The in vivo concentrations of tumor necrosis factor alpha and its soluble receptors were studied in patients in term labor and preterm labor. Amniotic fluid was retrieved from 175 women and tumor necrosis factor alpha, tumor necrosis factor receptor 1, and tumor necrosis factor receptor 2 concentrations were measured by highly sensitive immunoassays. Patients were classified in the following groups: (1) term labor (n = 29), (2) term not in labor (n = 29), (3) preterm labor leading to term delivery (n = 34), (4) preterm labor without infection resulting in preterm delivery (n = 34), (5) preterm labor with intra-amniotic infection (n = 23), and (6) second trimester (n = 26). RESULTS: Tumor necrosis factor alpha and tumor necrosis factor receptor 1 concentrations decreased with advanced gestational age (r = -0.51 and r = -0.7; P <.01 for each). (1) Patients in spontaneous term labor had a higher median concentration of tumor necrosis factor alpha than those at term not in labor (median, 6.4 pg/mL; range, 2.4->500 pg/mL vs median, 4.1 pg/mL; range, 1.1-22.7 pg/mL; P <.01) but had lower concentrations of tumor necrosis factor receptor 1 (median, 3.2 ng/mL; range, 1.3-9.1 ng/mL vs median, 4.2 ng/mL; range, 1.6-8.3; P <.001) and tumor necrosis factor receptor 2 (median, 5.5 ng/mL; range, 0.73-12.8 ng/mL vs median, 6.8 ng/mL; range, 2.9-12.9 ng/mL; P <.01). (2) In contrast, patients with preterm labor leading to preterm delivery had higher concentrations of tumor necrosis factor alpha (median, 12.3 pg /mL; range, 1.5->500 pg/mL vs median, 4.8 pg/mL; range, 1-60.9 pg/mL; P <.01), tumor necrosis factor receptor 1 (median, 8.8 ng/mL; range, 2.5-38 ng/mL vs median, 6.2 ng/mL; range, 1.4-28 ng/mL; P <.05), and tumor necrosis factor receptor 2 (median, 8.5 ng/mL; range, 3.5-45.4 ng/mL vs median, 6.1 ng/mL; range, 1.99-14.1 ng/mL; P <.01) than patients with preterm labor who delivered at term. (3) Microbial invasion of the amniotic cavity was associated with dramatic increases in the concentrations of tumor necrosis factor alpha (median, 93.5 pg/mL; range, 1.2->500 pg/mL) and its soluble receptors tumor necrosis factor receptor 1 (median, 8.8 ng/mL; range, 2.1-36.7 ng/mL) and tumor necrosis factor receptor 2 (median, 11.8 ng/mL; range, 3.4-46. 3 ng/mL), concentrations that were significantly higher than in those with preterm labor who delivered at term and those who delivered preterm but were not infected. CONCLUSION: The tumor necrosis factor alpha and tumor necrosis factor alpha soluble receptor profiles are different in term and preterm parturition. Our observations provide support for the thesis that preterm parturition is a pathologic condition. Increased tumor necrosis factor alpha soluble receptor concentrations may attenuate the deleterious effects of the excess of tumor necrosis factor alpha found in pathologic labor.

Amniotic Fluid↗

PubMed1997

Low pregravid body mass index as a risk factor for preterm birth: variation by ethnic group.

OBJECTIVE: To examine the association between pregravid body mass index (BMI) and preterm delivery among black, white, and Hispanic women. METHODS: Preterm deliveries among 12,459 women (43.2% black, 39.3% white, and 17.5% Hispanic) enrolled in a large multicenter trial of preterm birth prevention were examined by pregravid BMI category (very low, less than 16.5; low, 16.5-19.7; normal, 19.8-26.0; high, greater than 26) and by pathway (all, early, late, spontaneous preterm labor, and premature rupture of membranes [PROM]). RESULTS: More than one-fifth of both black (20.1%) and white (28.6%) women had low pregravid BMIs (less than 19.8), whereas only 11.7% of Hispanic women were under-weight. The overall prevalence of preterm delivery (gestational age less than 37 completed weeks) was 8.1% (10.3% in black, 7.3% in white, and 4.8% in Hispanic women). Among black and white women, bivariate analysis revealed an inverse linear association between pregravid BMI and the prevalence of all preterm deliveries (P < or = .001) and between pregravid BMI and the prevalence of late (33-36 weeks' gestation) preterm deliveries (P < .001). No such associations were observed for early (20-32 weeks' gestation) preterm delivery or among Hispanic women. Pregravid BMI was also associated inversely with spontaneous preterm labor among both black (P < or = .01) and white (P < .001) women, but not among Hispanic women. Logistic regression analysis (adjusting for the effects of maternal age, education, smoking, parity, previous preterm delivery, birth interval, and height) revealed that among black and white women, very low and low pregravid BMIs were associated with increased adjusted odds ratios for late (but not early) preterm delivery and for spontaneous preterm labor (but not PROM). CONCLUSIONS: These observations suggest that low pregravid BMI is associated with an increase in the prevalence of late preterm delivery and of spontaneous preterm labor among black and white, but not Hispanic, women.

Adolescent↗

PubMed1999

Racial differences in the patterns of singleton preterm delivery in the 1988 National Maternal and Infant Health Survey.

OBJECTIVES: To determine if the association between race and preterm delivery would persist when preterm delivery was partitioned into two etiologic pathways. METHODS: We evaluated perinatal and obstetrical data from the 1988 National Maternal and Infant Health Survey and classified preterm delivery as spontaneous or medically indicated. Discrete proportional hazard models were fit to assess the risk of preterm delivery for Black women compared with White women adjusting for potential demographic and behavioral confounding variables. RESULTS: Preterm delivery occurred among 17.4% of Black births and 6.7% of White births with a Black versus White unadjusted hazard ratio (HR) of 2.8 (95% CI = 2.4-3.3). The adjusted HR for a medically indicated preterm delivery showed no racial difference in risk (HR = 1.0, 95% CI = 0.4-2.6). However, for spontaneous preterm delivery between 20 and 28 weeks gestation, the Black versus White adjusted hazard ratio (HR) was 4.9 (95% CI = 3.4-7.1). CONCLUSIONS: Although we found an increased unadjusted HR for preterm delivery among Black women compared with White women, the nearly fivefold increase in adjusted HR for the extremely preterm births and the absence of a difference for medically indicated preterm delivery was unexpected. Given the differences in the risks of preterm birth between Black and White women, we recommend to continue examining risk factors for preterm delivery after separating spontaneous from medically indicated preterm birth and subdividing preterm delivery by gestational age to shed light on the reasons for the racial disparity.

Adolescent↗

PubMed2002

Maternal second-trimester serum ferritin concentrations and subsequent risk of preterm delivery.

We studied the relationship between maternal second-trimester serum ferritin concentrations and preterm delivery. The 312 preterm delivery cases, studied in aggregate and in subgroups [spontaneous preterm labour, preterm premature rupture of membranes, medically induced preterm delivery, moderate preterm delivery (gestational age at delivery 34-36 weeks) and very preterm delivery (gestational age at delivery <34 weeks)] were compared with 424 randomly selected women who delivered at term. Maternal ferritin concentrations, measured in serum collected at 17 weeks gestation on average, was determined using a two-site chemiluminometric immunoassay. Using multiple logistic regression, we derived maximum likelihood estimates of adjusted odds ratios (OR) and 95% confidence intervals [CI]. Elevation in maternal second-trimester ferritin was weakly associated with the risk of preterm delivery overall. After adjusting for possible confounding by maternal age, race/ethnicity, parity, Medicaid payment status and smoking during the index pregnancy, the OR for extreme quartiles (>64.5 vs. <26.0 ng/mL) of ferritin was 1.3 [95% CI 0.8, 2.1]. Stratified analyses indicated that elevated maternal serum ferritin was associated with an increased risk of preterm premature rupture of membranes (OR = 2.1; 95% CI 1.1, 4.1), but not with spontaneous preterm labour (OR = 0.9; 95% CI 0.4, 1.7) or medically induced preterm delivery (OR = 1.1; 95% CI 0.6, 2.0). The relationship between elevated maternal second-trimester serum ferritin concentrations and preterm delivery was strongest for spontaneous very preterm deliveries (<34 weeks gestation). Women with ferritin concentrations in the highest decile (>96 ng/mL) experienced a 2.7-fold increased risk of delivering before 34 completed weeks, compared with women with concentrations <26.0 ng/mL. These results are consistent with some previous reports, and further underline the potential for heterogeneity in the aetiology of preterm delivery.

Adult↗

PubMed2000

Preterm delivery in women with pregestational diabetes mellitus or chronic hypertension relative to women with uncomplicated pregnancies. The National institute of Child health and Human Development Maternal- Fetal Medicine Units Network.

OBJECTIVE: The purpose of this study was to compare the rates of indicated and spontaneous preterm delivery among women with chronic hypertension or pregestational diabetes mellitus with the rates among healthy women. STUDY DESIGN: This was a secondary analysis of data from healthy women with singleton gestations enrolled in a prospective observational study for prediction of preterm delivery (control group, n = 2738), women with pregestational diabetes mellitus requiring insulin therapy (n = 461), and women with chronic hypertension (n = 761). The two latter groups were enrolled in a randomized multicenter trial for prevention of preeclampsia. The main outcome measures were rates of preterm delivery, either spontaneous (preterm labor or rupture of membranes) or indicated (for maternal or fetal reasons), and neonatal outcomes. RESULTS: The overall rates of preterm delivery were significantly higher among women with diabetes mellitus (38%) and hypertension (33.1%) than among control women (13.9%). Rates were also significantly higher for delivery at <35 weeks' gestation. Women with diabetes mellitus had significantly higher rates of both indicated preterm delivery (21.9% vs 3.4%; odds ratio, 8.1; 95% confidence interval, 6.0-10.9) and spontaneous preterm delivery (16.1% vs 10.5%; odds ratio, 1.6; 95% confidence interval, 1.2-2.2) than did women in the control group. In addition, they had significantly higher rates of both indicated preterm delivery (odds ratio, 4.8; 95% confidence interval, 3.0-7.5) and spontaneous preterm delivery (odds ratio, 2.1; 95% confidence interval, 1.4-3.0) at <35 weeks' gestation than did control women. Compared with control women those with chronic hypertension had higher rates of indicated preterm delivery at both <37 weeks' gestation (21.9% vs 3.4%; odds ratio, 8.1; 95% confidence interval, 6.2-10.6) and at <35 weeks' gestation (12.1% vs 1.6%; odds ratio, 8.2; 95% confidence interval, 5.7-11.9), but there were no differences in rates of spontaneous preterm delivery. CONCLUSION: The increased rate of preterm delivery among women with chronic hypertension relative to control women was primarily an increase in indicated preterm delivery, whereas the rates of both spontaneous and indicated preterm delivery were increased among women with pregestational diabetes mellitus.

Adult↗

PubMed2005

Does progesterone treatment influence risk factors for recurrent preterm delivery?

OBJECTIVE: To examine how demographic and pregnancy characteristics can affect the risk of recurrent preterm delivery and the how the effectiveness of progesterone treatment for prevention alters these relationships. METHODS: This was a secondary analysis of a randomized trial of 17alpha-hydroxyprogesterone caproate to prevent recurrent preterm delivery in women at risk. Associations of risk factors for preterm delivery (less than 37 completed weeks of gestation) were examined separately for the women in the 17alpha-hydroxyprogesterone caproate (n = 310) and placebo (n = 153) groups. RESULTS: Univariate analysis found that the number of previous preterm deliveries and whether the penultimate delivery was preterm were significant risk factors for preterm delivery in both the placebo and progesterone groups. High body mass index was protective of preterm birth in the placebo group. Multivariate analysis found progesterone treatment to cancel the risk of more than 1 previous preterm delivery, but not the risk associated with the penultimate pregnancy delivered preterm. Obesity was associated with lower risk for preterm delivery in the placebo group but not in the women treated with progesterone. CONCLUSION: The use of 17alpha-hydroxyprogesterone caproate in women with a previous preterm delivery reduces the overall risk of preterm delivery and changes the epidemiology of risk factors for recurrent preterm delivery. In particular, these data suggest that 17alpha-hydroxyprogesterone caproate reduces the risk of a history of more than 1 preterm delivery. LEVEL OF EVIDENCE: I.

17 alpha-Hydroxyprogesterone Caproate↗

PubMed2006

Umbilical serum concentrations of chemokines (RANTES and MGSA/GRO-alpha) in preterm and term neonates.

BACKGROUND: The objective of this study was to explore the relationship between labor (preterm and term) and umbilical blood serum regulated on activation, normal T cell expressed and secreted (RANTES) and melanoma growth stimulatory activity/growth-related oncogene-a (MSGA/GRO-alpha) concentration, and to determine whether early sepsis and pneumonia are associated with changes in concentrations of the chemokines (RANTES and MSGA/GRO-alpha) in umbilical blood serum. METHODS: Umbilical blood was obtained from 67 neonates in the following groups: (i) preterm neonates with early sepsis; (ii) preterm neonates with pneumonia; (iii) non-infected preterm neonates; and (iv) full-term healthy neonates. RANTES and MGSA/GRO-alpha concentrations were determined by use of a commercially available immunoassay kit. RESULTS: Non-infected preterm neonates had lower RANTES concentrations than healthy term neonates. Preterm infected neonates (pneumonia or sepsis) did not have higher RANTES concentrations than non-infected preterm neonates. In contrast, non-infected preterm neonates had higher MSGA/GRO-alpha concentrations than full-term healthy neonates. And preterm neonates with sepsis had higher MGSA/GRO-alpha concentrations than preterm ones with pneumonia and non-infected preterm ones. CONCLUSIONS: Preterm neonates had constitutively lower RANTES concentrations than term ones and it seems that during infection RANTES concentrations did not increase. MGSA/GRO-a concentrations were constitutively higher in preterm than term neonates, and septic events further increased its concentrations in preterm neonates.

Bacteremia↗

PubMed2006

Diagnosis of early preterm labour.

While preterm contractions occur almost as often extremely preterm as they do closer to term, birth due to spontaneous preterm labour before 27 weeks of gestation is rare, accounting for 0.05-0.7% of all births in different populations. Although the likelihood that uterine contractions before 27 weeks of gestation represent true preterm labour is low, the risk of adverse outcome in such cases is high. A correct diagnosis is important, and a useful diagnostic test should have a high sensitivity. In most reports, only 30-40% of women hospitalised for spontaneous preterm labour experience a preterm birth, suggesting a low positive predictive value of clinical diagnosis based on uterine contractions and vaginal examination. Transvaginal ultrasonographic scanning (TVUSS) of cervical length has shown a high sensitivity for preterm birth, 90-100% for preterm birth before 33-35 weeks, using a liberal cutoff at 30 mm. Assessment of cervicovaginal fetal fibronectin (FFN) levels has shown a sensitivity of about 80%. Adding FFN assessment to TVUSS might contribute insignificantly to the prediction of preterm birth. In a retrospective study of 147 women with spontaneous preterm labour and intact membranes before 27 weeks in our department, 61% of hospitalised women and 77% of women receiving tocolytic infusion therapy delivered before 32 weeks. Among 66 singleton pregnancies delivered before 32 weeks, at admission, 94% either had an effaced cervix or cervix with >/=2 cm dilation (74%), vaginal bleeding (61%) or serum C-reactive protein level >20 mg/l (40%), whereas one of these findings only was present in 18% of women who delivered at later gestations. Among 132 women with symptoms of spontaneous preterm contractions before 27 weeks not admitted for hospital care, only 2 (1.5%) delivered before 32 weeks, not significantly higher than for all other women (0.6%). Although TVUSS may be useful when the diagnosis of spontaneous preterm labour is in doubt, the main predicament in early spontaneous preterm labour may not be to predict preterm birth but to prevent it, since many women appear in advanced labour or with manifest chorioamnionitis.

Biomarkers↗

PubMed2000

Perinatal factors and preterm delivery in an Irish obstetric population.

The aim of this study was to ascertain the incidence of preterm delivery, the associated etiological factors and consequent perinatal mortality in an Irish obstetrical population. All deliveries between 24 + 0 and 36 + 6 weeks of gestation that occurred during the five year period 1992-1996 were included in the study. The overall group of preterm deliveries was also analyzed separately as an early preterm group (24 + 0-31 + 6 weeks gestation) and a late preterm group (32 + 0-36 + 6 weeks gestation). The overall incidence of preterm delivery was 5.5% (n = 683) with 1% (n = 122) occurring in the early preterm group and 4.5% (n = 561) in the late preterm group. The etiological factors contributing to preterm delivery in our population together with their frequency of occurrence in both early and late preterm groups are outlined. Spontaneous unexplained preterm delivery, multiple pregnancy, and hypertensive disorders of pregnancy were the commonest etiological factors for preterm delivery. The perinatal mortality rate (PMR) was 57 per 1000 (n = 39) in the preterm group overall with a 213/1000 PMR in the early preterm group and a 23/1000 PMR in the late preterm group.

Chorioamnionitis↗

PubMed2005

Anaphylatoxins in preterm and term labor.

OBJECTIVE: The complement system plays a central role in the first line of defense against invading pathogens, and its activation involves the release of potent pro-inflammatory mediators such as anaphylatoxins C3a, C4a and C5a. The aim of this study was to determine whether differences existed in maternal plasma anaphylatoxin concentrations between patients with term and preterm parturition. STUDY DESIGN: A cross-sectional study was designed to determine the plasma anaphylatoxin concentrations in 296 pregnant women in the following groups: 1) normal pregnancy between 20-36 6/7 weeks (n=64); 2) term not in labor (n=70); 3) term in labor (n=60); and 4) preterm labor with intact membranes (n=102). Women with preterm labor were classified into: a) term delivery (n=24); b) preterm delivery without intra-amniotic infection (IAI) (n=62); and c) preterm delivery with IAI (n=16). Concentrations of C3a, C4a and C5a were determined by ELISAs. Statistical analysis was conducted with non-parametric methods. RESULTS: 1) The median plasma C5a concentration was lower in women at term in labor than in those not in labor (P<0.001). In contrast, there were no differences in plasma C3a and C4a concentrations between the two groups (P>0.05). 2) Among patients with preterm labor, those with IAI had a higher median plasma C5a concentration than those without IAI and those who delivered at term (post-hoc tests P<0.001 and P=0.01, respectively). When comparing the preterm labor subgroups with normal pregnancy, only women with preterm delivery and IAI had a median plasma C5a concentration higher than that of normal pregnant women (Kruskal-Wallis P<0.001, post hoc test P<0.001). There was no difference in the plasma C4a concentration among patients with preterm labor. The median plasma C3a concentration in patients with preterm labor with IAI was higher than in those without IAI (Kruskal-Wallis P=0.01, and post-hoc test P=0.005). There was no difference in the plasma C3a concentrations between women with preterm labor who delivered at term and those with preterm delivery, with or without IAI. In addition, no differences were observed in the median plasma C3a concentration between women with normal pregnancy and those in each of the preterm labor subgroups. CONCLUSIONS: The maternal plasma concentration of anaphylatoxin C5a is increased in women with preterm labor and IAI, but not in spontaneous labor at term.

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