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PubMed2001

Sexual activity during late pregnancy and risk of preterm delivery.

OBJECTIVE: To examine the association between sexual activity during late pregnancy and preterm delivery. METHODS: Women at least 16 years old and carrying singleton fetuses were recruited between 24 and 29 weeks' gestation from prenatal clinics in central North Carolina. They were interviewed by telephone about sexual activity before and during pregnancy. One hundred eighty-seven women delivered between 29 and 36 weeks and had a follow-up interview after delivery. Four hundred nine women who were selected randomly from the cohort served as controls and had a follow-up interview between 29 and 36 weeks (mean gestational age 39.2 weeks). RESULTS: Intercourse during late pregnancy was associated with a reduced risk of preterm delivery. The conditional odds ratio (OR) was 0.34 and 95% confidence interval (CI) 0.23, 0.51 for preterm delivery within 2 weeks after intercourse. Similar decreased risk for preterm delivery was found with recent female orgasm. Adjusting for race, age, education, and living with a partner had little effect on results. Cases were more likely than controls to report poorer health, medical reasons for reducing sexual activity, less interest in sex, and receipt of advice to restrict sexual activity during pregnancy. Results did not differ substantially according to presence or absence of bacterial vaginosis at 28 weeks. CONCLUSION: These data provide evidence against the hypothesis that sexual activity generally increases risk of preterm delivery between 29 and 36 weeks. However, we cannot exclude the possibility that a small subgroup of susceptible women might have adverse consequences of sexual activity.

Adult↗
PubMed2002

Neighborhood socioeconomic status, maternal race and preterm delivery: a case-control study.

PURPOSE: To explore associations between neighborhood socioeconomic context and preterm delivery, independent of maternal and family socioeconomic status, in African-American and white women. METHODS: A case-control study of African-American (n = 417) and white (n = 1244) women delivering infants at the University of California, San Francisco's Moffitt Hospital, between 1980 and 1990. RESULTS: Neighborhood socioeconomic contexts were associated with preterm delivery but associations were non-linear and varied with race/ethnicity. For African-American women, living in a neighborhood with either high or low median household income was associated with an increased risk of spontaneous preterm delivery, as was living in a neighborhood with large increases or decreases in the proportion of African-American residents during the study decade. Residence in neighborhoods with high and low rates of male unemployment was associated with a decreased risk of preterm delivery. Among white women only large positive and negative changes in neighborhood male unemployment were associated with risk of preterm delivery. CONCLUSIONS: Neighborhood factors and changes in neighborhoods over time are related to preterm delivery, although the mechanisms linking local environments to maternal risk remain to be specified.

Adult↗
PubMed2005

Bacterial infections--the cause of preterm delivery.

Within diagnostic procedures protocols in preterm delivery, the objective of the study was to examine bacterial causes of preterm deliveries in relation to term deliveries. The study included 106 patients delivered before term (24 to 37 weeks of gestation) and 126 patients with term delivery after 37 to 42 weeks of gestation. Bacterial analysis included hospital material: cervix smear in patients before the delivery and protective and functional fetal elements.

Bacterial Infections↗
PubMed1997

Angiogenin: a marker for preterm delivery in midtrimester amniotic fluid.

OBJECTIVE: Neovascularization is a response of tissue to ischemic damage. Placental ischemia is thought to underlie a significant portion of preterm deliveries. Our objective was to evaluate whether angiogenin, a potent inducer of neovascularization, is increased in midtrimester amniotic fluid of patients destined to be delivered preterm. STUDY DESIGN: We designed a case-control study of singleton gestations undergoing midtrimester amniocentesis for standard genetic indications. Inclusion criteria were (1) pregnancy outcome information available, (2) gestational age at amniocentesis 15 to 20 weeks, (3) no evidence of fetal structural or chromosomal anomalies, and (4) absence of conditions associated with preterm delivery. Amniotic fluid angiogenin levels were measured by immunoassay and normalized by natural log transformation for statistical analysis. RESULTS: Eleven patients with preterm deliveries were matched with 33 controls. Amniotic fluid angiogenin levels were significantly higher in patients with preterm deliveries compared with controls (median 30.1 ng/ml [range 13.6 to 71.0 ng/ml] vs 17.8 ng/ml [7.8 to 43.3 ng/ml], p = 0.002). Demographic data were not significantly different. The association between angiogenin levels and preterm delivery persisted after small-for-gestational-age neonates were excluded (p = 0.02). Receiver-operator characteristic curve analysis showed that an angiogenin level of 31.0 ng/ml was the optimal cutoff point for prediction of preterm delivery (sensitivity 45.5%, specificity 91.0%, p = 0.03, odds ratio 6.0). CONCLUSIONS: Midtrimester amniotic fluid angiogenin levels are elevated in patients with preterm delivery. This supports the theory that preexisting intrauterine ischemia and inflammation are important risk factors for preterm delivery and may be already present in the early midtrimester.

Adult↗
PubMed1993

Preterm delivery among black and white enlisted women in the United States Army.

OBJECTIVE: To examine black-white differences in preterm delivery in a healthy population who had unrestricted access to prenatal care. METHODS: We conducted a retrospective cohort study of 842 black and 1026 white enlisted servicewomen who delivered a singleton infant of 20 or more weeks' gestation from July 1, 1987 through September 30, 1990 at four Army Medical Centers in the United States. Data were collected by reviewing maternal and newborn records. We used logistic and proportional hazards regression models to analyze outcomes defined by length of gestation, cause of preterm delivery, and jointly by length and cause. RESULTS: Black enlisted women had a cumulative probability of preterm delivery (13.5%) that was higher than that for white enlisted women (10.5%) (hazard ratio 1.31, 95% confidence interval [CI] 1.002-1.70). However, the ratio of black-to-white hazards was not uniform. Black-white differences were small and nonsignificant from 33-36 weeks' gestation, when most preterm deliveries occur. The differences were also small and nonsignificant for deliveries related to spontaneous rupture of membranes or idiopathic preterm labor, the most common causes of preterm delivery. The black-to-white hazard ratios were greatest for all deliveries before 33 weeks' gestation and for medically indicated preterm deliveries. CONCLUSIONS: Efforts to reduce black-white differences in preterm delivery must go beyond providing prenatal care and eliminating recreational drug use. Future studies should consider black-white differences in environments during the mother's own development and in psychosocial and physical stresses during pregnancy.

Adolescent↗
PubMed2006

Assessing the relationship between preterm delivery and various microorganisms recovered from the lower genital tract.

OBJECTIVE: To determine if the likelihood of preterm delivery is more dependent on the specific organisms present in the vagina than on the presence of bacterial vaginosis. METHODS: We evaluated the vaginal fluid of a prospective cohort of women at 23-32 weeks of gestation with signs and symptoms of preterm labor and intact membranes. Forward stepwise logistic regression models were used to evaluate the relationship between preterm delivery and the presence of anaerobic bacteria, Gardnerella, ureaplasmas and mycoplasmas, and sialidase. RESULTS: The cohort included 137 women, and complete delivery information was available for 134 of them. The rate of preterm delivery was 28% (37 of 134). Mycoplasma genitalium independently was associated with spontaneous preterm delivery (OR 3.48; 95% CI 1.41, 8.57). After controlling for this factor, none of the other variables were significantly prognostic for spontaneous preterm delivery (residual overall p = 0.19). CONCLUSION: The presence of Mycoplasma genitalium in the vagina of pregnant women is an independent risk factor for spontaneous preterm delivery.

Adult↗
PubMed2002

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.

Adult↗
PubMed2006

Bacterial vaginosis and group B streptococcal colonization and preterm delivery in a low-risk population.

OBJECTIVE: To evaluate the relationship between bacterial vaginosis (BV) and group B streptococcal (GBS) colonization in the 2nd trimester of pregnancy and preterm delivery. METHODS: 1,197 pregnant women between 22 and 25 weeks' gestation had a high vaginal swab for assessment of BV and GBS. Exclusion criteria were: previous preterm delivery, or mid-trimester abortion or termination of pregnancy, multiple gestation, oligo- or polyhydramnios, placenta previa, fetal abnormalities, uterine malformations, cervical incompetence, cervical cerclage, or receipt of an antibiotic effective against BV or GBS following the screening. All women had no risk factors for preterm delivery. The primary outcome measure in this analysis was spontaneous preterm delivery before 37 weeks' gestation. RESULTS: The preterm delivery rate was 8.7%, while the maternal BV and GBS colonization rates were 7.9 and 12.5%, respectively. Following adjustment for potential confounders BV was associated with an increased risk of preterm delivery (RR 2.19; CI: 1.21-3.98) (p = 0.01). On the contrary, GBS colonization was found to have a negative correlation with preterm birth (RR 0.43; 95% CI: 0.19-1.00). CONCLUSIONS: Although BV is a risk factor for preterm delivery, GBS colonization in the 2nd trimester of pregnancy has an inverse correlation with preterm delivery.

Adult↗
PubMed1997

Cervical ultrasonography compared with manual examination as a predictor of preterm delivery.

OBJECTIVE: Our purpose was to compare the accuracy of ultrasonographic and manual cervical examinations for the prediction of preterm delivery. STUDY DESIGN: One hundred two singleton pregnancies at high risk for preterm delivery were followed up prospectively from 14 to 30 weeks with both serial cervical ultrasonography measurements and manual examinations of the length of the cervix. The primary outcome studied was preterm (< 35 weeks) delivery. RESULTS: Excluding six induced preterm deliveries, 96 pregnancies were analyzed. The mean cervical length measured by ultrasonography was 20.6 mm in pregnancies delivered preterm (n = 17) and 31.3 mm in pregnancies delivered at term (n = 79) (p = 0.003); the mean cervical lengths measured by manual examination were 16.1 mm and 18.6 mm in the same preterm and term pregnancies, respectively (not significant). The sixteenth- and twentieth-week ultrasonographic cervical lengths predicted preterm delivery most accurately (p < 0.0005). The 25th percentiles of ultrasonographic (25 mm) and manual (16 mm) cervical lengths showed relative risks for preterm delivery of 4.8 (95% confidence interval 2.1 to 11.1, p = 0.0004) and 2.0 (95% confidence interval 0.5 to 4.7, p = 0.1), respectively; sensitivity, specificity, and positive and negative predictive values were 59%, 85%, 45%, 91%, and 41%, 77%, 28%, and 86%, respectively. CONCLUSION: Cervical length measured by ultrasonography is a better predictor of preterm delivery than is cervical length measured by manual examination. Cervical ultrasonography in patients at high risk for preterm birth seems to be most predictive of preterm delivery when it is performed between 14 and 22 weeks' gestation.

Cervix Uteri↗
PubMed1999

[Preterm delivery: detection of risks and preventive treatment].

Every year around the world some 13 million premature children are born. Most of these children are born in developing countries, and they account for the largest share of perinatal morbidity and mortality. This review study analyzed scientifically validated data on interventions to prevent at least some portion of these preterm deliveries and to lessen their impact on neonatal health. The Cochrane and MEDLINE bibliographic databases were consulted. Fifty review pieces and research articles were studied, relating to the following aspects of preterm delivery: risk factors and early detection of the risk of preterm delivery; preventing the risk of preterm delivery; treating preterm delivery once it has begun; and preventing neonatal respiratory distress syndrome. There were few successful approaches to the prediction, prevention, or early detection of the threat of preterm delivery. The only measures that can be recommended for all pregnant women are screening for and treating asymptomatic bacteriuria as a part of prenatal check-ups. Screening for bacterial vaginosis and treating it reduce the incidence of preterm births in pregnant women with a history of premature delivery. In addition, prophylactic cerclage decreases the incidence of premature births in pregnant women who have had more than three preterm births. To treat a delivery that starts early, with or without premature membrane rupture, the interventions that have proved to be effective are administering betamimetics to the parturient woman in order to delay delivery for 48 hours, and using indomethacin for the same purpose, as the second-choice drug. The prenatal administration of corticosteroids to the pregnant woman can induce lung maturation in the fetus and reduce respiratory distress syndrome and ventricular hemorrhage, thus decreasing neonatal mortality. There is a need to continue and support basic and epidemiological research in order to develop new knowledge on the causes and mechanisms of preterm delivery and on preventing the morbidity and mortality that preterm delivery produces.

Female↗
PubMed2005

Factors associated with preterm delivery in mothers of children with Beckwith-Wiedemann syndrome: a case cohort study from the BWS registry.

Pregnancy that results in a child with Beckwith-Wiedemann syndrome (BWS) is associated with preterm delivery. Based on previous case series, we hypothesized that preterm delivery of a child with BWS was due to known risk factors for preterm delivery such as polyhydramnios and gestational hypertension. A case cohort study using the BWS Registry at Washington University School of Medicine was undertaken. Cases were pregnancies that resulted in the birth of a child with BWS, controls were pregnancies resulting in the birth of siblings without BWS. Univariate analyses of maternal complications and logistic regression to predict preterm delivery were used. Children with BWS (n = 304) were delivered preterm at a significantly higher rate than their siblings (n = 269) odds ratio 19.1 (95% CI 9.1-40.2). Polyhydramnios, gestational hypertension, and vaginal bleeding also occurred at high rates in the BWS group with odds ratios of 31.6 (95% CI 12.6-79.1), 2.4 (95% CI 1.4-4.1), and 3.9 (95% CI 2.3-6.4), respectively. In a multivariate logistic regression model within the BWS group, polyhydramnios, vaginal bleeding, and gestational hypertension were significant predictors of preterm delivery, odds ratios of 2.9 (95% CI 1.6-5.4), 2.6 (95% CI 1.3-5.0), and 5.3 (2.3-12.0), respectively. However, a significant proportion, 6.5% (18 of 277), of patients in the BWS group delivered preterm without known risk factors. Preterm delivery of a child with BWS is associated with an increased frequency of polyhydramnios, gestational hypertension, and vaginal bleeding in the mother. However, preterm delivery also occurs in the absence of these risk factors.

Adolescent↗
PubMed2001

Molecular epidemiology of preterm delivery: methodology and challenges.

Preterm delivery (PTD) appears to be a complex trait determined by both genetic and environmental factors. Few studies have examined genetic influence on PTD. The overall goal of our study is to examine major candidate genes of PTD and to test gene-environment interactions. Our study includes 500 preterm trios, including 500 preterm babies and their parents and 500 maternal age-matched term controls. We will perform the transmission/disequilibrium test (TDT) on candidate genes thought to be important in each of the four biological pathways of PTD: (1) decidual chorioamionotic inflammation: interleukin 1 (IL-1), IL-6, and tumour necrosis factor (TNF); (2) maternal and fetal stress: corticotropin-releasing hormone (CRH); (3) uteroplacental vascular lesions: methylenetereahydrofolate reductase (MTHFR); and (4) susceptibility to environmental toxins: GSTM1, GSTT1, CYP1A1, CYP2D6, CYP2E1, NAT2, NQO1, ALDH2, and EPHX. We will also perform standard case-control analyses on the 500 preterm cases and 500 term controls to examine gene-environment interactions. The major environmental, nutritional and social factors as well as clinical variables known or suspected to be associated with PTD will be used to test for gene-environment interactions. This study integrates epidemiological and clinical data as well as genetic markers along major pathogenic pathways of PTD. The findings from this study should improve our understanding of genetic influences on PTD and gene-environment interactions.

Adult↗
PubMed2004

The effect of phosphoramidon on inflammation-mediated preterm delivery in a mouse model.

OBJECTIVE: Several metallopeptidases have been implicated in both term and preterm parturition. We hypothesize that endotoxin-induced preterm delivery can be prevented by the administration of a metallopeptidase inhibitor. STUDY DESIGN: We used an animal model of endotoxin-induced preterm delivery in timed pregnancy C57Bl/6 mice. Test animals received lipopolysaccharide followed by phosphoramidon, either every 1.5 or every 3 hours. Control mice received lipopolysaccharide followed by buffer injections at the same intervals. The primary outcome was a preterm delivery rate. RESULTS: The rate of preterm delivery for the control animals was 88.0% compared with the treatment groups of 45.5% for the mice that received phosphoramidon every 3 hours and 30.8% for the group that received it every 1.5 hours (P<.01). CONCLUSION: The administration of a metallopeptidase inhibitor resulted in a decreased rate of preterm delivery in this animal model.

Animals↗
PubMed1982

Effects of cigarette smoking, alcohol, coffee and tea consumption on preterm delivery.

A case-control study of 175 mothers of singleton, preterm infants and 313 mothers of singleton, term infants was undertaken at Yale-New Haven Hospital during 1977 to explore possible risk factors of preterm delivery. Heavy alcohol consumption (an average of two or more drinks per day) during the pregnancy was associated with an approximately 3-fold risk of preterm delivery. Women who smoked 10 or more cigarettes per day were also at an increased risk of a preterm delivery, but the effect of cigarette smoking was less pronounced once confounding variables had been taken into account. No association was observed between coffee drinking and shortened gestations. Tea consumption, especially four or more cups of tea per day, was more frequent among women with a preterm as compared to a term infant, but no significant relation was evident between heavy tea consumption and preterm delivery after controlling for the effects of other risk factors.

Adolescent↗
PubMed2006

Maternal obesity in early pregnancy and risk of spontaneous and elective preterm deliveries: a retrospective cohort study.

OBJECTIVES: We sought to determine the association between maternal body mass index and risk of preterm delivery. METHODS: We assessed 187,290 women in Scotland and estimated adjusted odds ratios for spontaneous and elective preterm deliveries among overweight, obese, and morbidly obese women relative to normal-weight women. RESULTS: Among nulliparous women, the risk of requiring an elective preterm delivery increased with increasing BMI, whereas the risk of spontaneous preterm labor decreased. Morbidly obese nulliparous women were at increased risk of all-cause preterm deliveries, neonatal death, and delivery of an infant weighing less than 1000 g who survived to 1 year of age (a proxy for severe long-term disability). By contrast, obesity and elective preterm delivery were only weakly associated among multiparous women. CONCLUSIONS: Obese nulliparous women are at increased risk of elective preterm deliveries. This in turn leads to an increased risk of perinatal mortality and is likely to lead to increased risks of long-term disability among surviving offspring.

Adult↗
PubMed1997

Time to pregnancy and preterm delivery.

OBJECTIVE: To test whether subfertile women may be at higher risk of preterm delivery. METHODS: We used data from two population-based cohort studies on risk factors and pregnancy outcome for approximately 20,000 deliveries in three major Danish obstetric departments. The Aalborg-Odense study comprised all pregnant women attending routine antenatal care at two obstetric departments from 1984 to 1987. In all, 11,850 women (86%) filled in a questionnaire at about 36 weeks' gestation. The Aarhus study addressed women at the routine visit near 16 weeks' gestation from 1989 to 1991; a study questionnaire was returned by 6857 (80%). Both studies excluded women with chronic illnesses, multiple fetuses, and inability to speak Danish. Only women with planned pregnancies were included in the analysis. In all, 8855 and 3985 women from Aalborg-Odense and Aarhus, respectively, were eligible for the analyses. In both cohorts, women were categorized according to their waiting time to pregnancy (0-6 months, 7-12 months, and greater than 1 year) and according to examination or treatment for infertility (yes, no). Preterm delivery was defined as birth before 37 completed weeks. RESULTS: Compared with women who tried for 6 months or less before they conceived, women who tried for 7-12 months had 1.3 times (95% confidence interval [CI] 0.8, 2.1) the adjusted risk of preterm delivery in both cohorts, and women with a time to pregnancy of greater than 12 months had adjusted relative risks for preterm delivery of 1.6 (95% CI 1.1, 2.2) for Aalborg-Odense and 1.7 (95% CI 1.1, 2.6) for Aarhus. The results remained similar after excluding women with infertility treatment. CONCLUSIONS: Pregnant women with subfertility and clinically defined infertility are more prone to preterm delivery, even in the absence of infertility treatment.

Adult↗
PubMed2000

Amniotic fluid interleukin-6 and preterm delivery: a review.

OBJECTIVE: To evaluate the potential role of amniotic fluid (AF) interleukin (IL)-6 as a predictor of preterm delivery and to consider possible explanations for the proportion of women with elevated AF IL-6 who deliver preterm yet lack microbiologically detectable intra-amniotic infection. DATA SOURCES: We searched the English language human literature in MEDLINE, 1966 through September 1999, using the keywords "labor/infant," "premature," "cytokines/interleukin-6," and "AF." We also examined abstracts from the 1999 meetings of the Society for Maternal-Fetal Medicine and the Society for Epidemiologic Research. We identified other studies by reviewing the reference lists of published articles. METHODS OF STUDY SELECTION: The MEDLINE search yielded 55 citations. We focused on studies that reported on the association between AF IL-6 and preterm delivery. TABULATION, INTEGRATION, AND RESULTS: There is consensus in the literature that elevated AF IL-6 is a stronger predictor of preterm delivery than intra-amniotic infection detected by either microbiologic culture or polymerase chain reaction (PCR). Among women with elevated AF IL-6, PCR could detect a higher proportion of intra-amniotic infection than culture. A number of women with elevated AF IL-6 (33-70%) deliver preterm and do not have evidence of intra-amniotic infection by either culture or PCR. Possible explanations for this observation are considered. CONCLUSION: Elevated AF IL-6 is strongly associated with preterm delivery and merits future consideration in clinical settings to predict preterm delivery and guide patient care. Development of improved polymerase chain reaction-based clinical methods to detect intra-amniotic infection is necessary to better understand the relationship between elevated AF IL-6, intra-amniotic infection, and preterm delivery.

Amniotic Fluid↗
PubMed1995

Markers of infection and their relationship to preterm delivery.

In this study we evaluated different markers of infection and their relationship to preterm delivery. Forty-four consecutive women with singleton pregnancies in uncomplicated preterm labor were investigated. C-reactive protein (CRP) in peripheral maternal blood, amniotic fluid cytokines, amniotic fluid leukocyte count, and amniotic fluid culture were performed in all patients. Thirty-six patients responded to standard tocolytic therapy and delivered after 34 weeks' gestation. In eight patients treatment failed and they delivered before 34 weeks' gestation. Two of these eight patients had a positive amniotic fluid culture for Ureaplasma urealyticum. The positive culture was accompanied by an elevated neutrophil count in the amniotic fluid. Elevated amniotic fluid levels of tumor necrosis factor (TNF) (more than 23 pg/mL), interleukin-6 (IL-6) (more than 2292 pg/mL) and interleukin-8 (more than 164 pg/mL) correlated with early preterm delivery. CRP levels in serum had a low sensitivity (38%) but a high specificity (94%) in predicting preterm delivery. This study indicates that preterm labor can be initiated by infection. Markers of infection obtained by amniocentesis have a better sensitivity and positive predictive value than noninvasive markers. Elevated IL-6 (more than 2292 pg/mL) seems to be the best predictor for preterm delivery, with a sensitivity of 75% and a specificity of 97%.

Amniocentesis↗