Preterm labor, preterm delivery, intrauterine infection, and preterm rupture of membranes.
Explore the source record for details and available documents.
Abortion, Spontaneous↗
SEARCH · PubMed Health
Results for “preterm labor”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Pharmacologic inhibition of preterm labor.
Preterm labor is responsible for a majority of cases of perinatal morbidity and deaths. Prevention of preterm labor is not usually possible; thus pharmacologic treatment is the only recourse available. Numerous agents have been used to treat preterm labor, but none has proved to be superior. This report reviews the current information available about the pharmacology of labor-inhibiting drugs and discusses the clinical approach to the management of preterm labor.
Adrenergic beta-Agonists↗
Trends in preterm labor.
Preterm birth has been identified by the National Commission to Prevent Infant Mortality (1988) as the primary cause of the increased infant mortality rate in the United States. An analysis of what is currently known about four areas of preterm labor including (1) definition and causes, (2) identification of patients at risk, (3) management techniques, and (4) use of patient education in labor is presented in this paper. Preterm labor is defined as uterine contractions that occur between 20 and 37 weeks' gestation with progressive cervical dilatation or effacement or both. Directions for future research are discussed.
Female↗
Symptoms that precede preterm labor and preterm premature rupture of the membranes.
Great emphasis has been placed on recognition of the early warning symptoms of preterm labor by both pregnant women and health care providers. In addition to the expected increase in both painless and painful uterine contractions, several symptoms have been commonly cited in textbooks and patient educational materials as preceding preterm labor including menstrual-like cramps, backache, pelvic pressure, and an increased amount of vaginal discharge. We interviewed 107 women with preterm labor, 102 women with preterm prematurely ruptured membranes, and 106 ambulatory normal pregnant women to ascertain the frequency of each of eight putative warning symptoms of preterm labor in each group. Preterm labor patients were distinguished as expected from both normal women and amniorrhexis patients by a greater frequency of painful and painless contractions. Menstrual cramps, backache, and increased vaginal discharge, symptoms often said to be normally present in pregnancy, were also significantly more common in preterm labor patients than in women with preterm membrane rupture and in normal subjects.
Adolescent↗
Effect of exercise on uterine activity in the patient in preterm labor.
Preterm labor patients are at risk for physiologic complications associated with long-term bed rest. Although conditioning exercise programs are recommended for patients confined to bed rest, no studies have been reported that have evaluated the effects of exercise on uterine activity in women with preterm labor. A pilot study with 10 women was conducted to evaluate the short-term effects of exercise with a protocol involving pretesting and posttesting of uterine activity. The results indicated minimal changes in the frequency of uterine contractions after exercise. Future research is recommended with larger and more diverse samples to evaluate both short- and long-term effects of exercise throughout high-risk pregnancies.
Adult↗
The role of chorioamnionitis and prostaglandins in preterm labor.
Spontaneous preterm labor remains a significant cause of high morbidity and mortality in the newborn. Chorioamnionitis with an associated rise in prostaglandins (PGs) is thought to be one of the factors responsible for the onset of preterm labor. In this study, 52 placentas and membranes from gestations of 35 weeks' or fewer were collected. Tissue samples of membranes and placentas were incubated in pseudoamniotic fluid, and the levels of PGs and leukotriene B4 were assayed. Swallowed amniotic fluid aspirated from the infants' stomachs was analyzed for PGs and examined microscopically for the presence of degenerate neutrophilic polymorphonuclear leukocytes (pus cells) and bacterial organisms. Prostaglandins E and F and leukotriene B4 production were significantly higher in the membranes and placentas with chorioamnionitis than in those without. Although the comparison of PG levels in the gastric fluid of infants with and without chorioamnionitis did not reach statistical significance, there was a trend toward higher levels of PGs with chorioamnionitis. Prostaglandin E levels from membranes and placentas and PGF from placentas were significantly elevated in the gastric fluid of infants with pus cells and organisms. These findings support the hypothesis that chorioamnionitis may initiate preterm labor.
Chorioamnionitis↗
A critical assessment of preterm labor prevention strategies.
Preterm birth is second only to congenital diseases in causing morbidity and mortality in infants. To prevent preterm labor and delivery, a number of strategies have been developed. When choosing a strategy to prevent preterm birth, however, physicians must remember that preterm delivery arises from three separate conditions: iatrogenic preterm labor, premature rupture of membranes, and idiopathic preterm labor. Many of the programs that have been developed focus on patients who are at high risk for iatrogenic preterm birth and premature rupture of membranes, but do not include patients who are likely to experience idiopathic preterm labor. Since idiopathic preterm labor is the most common cause of preterm birth and is the most amenable to early intervention with tocolytic agents, more preterm labor education efforts should be included in prenatal care programs. In addition, further research is needed to delineate which features of preterm birth prevention programs are responsible for the beneficial effects that have been observed.
Clinical Trials as Topic↗
Does evidence of inflammation on Papanicolaou smears of pregnant women predict preterm labor and delivery?
BACKGROUND: Preterm delivery is the most common cause of neonatal morbidity and mortality in the United States. There is evidence that cervicovaginal infection could predispose to preterm labor. This study explored a possible association of evidence of inflammation on an otherwise normal Papanicolaou smear obtained during pregnancy with subsequent preterm labor and preterm delivery. METHODS: Using a retrospective matched cohort design, we studied women who gave birth to live singleton infants at the University of Missouri Hospital and Clinics during a 21-month period. Papanicolaou smears were obtained from 1 to 8 months before delivery and were interpreted in the same cytopathology laboratory. Data pertaining to outcome variables and potential confounding variables were collected from hospital charts. RESULTS: Incidence rates were 14.4 percent for labor < 37 weeks' gestation (preterm labor), 12.3 percent for hospitalization for preterm labor, 9.9 percent for delivery < 37 weeks (preterm delivery), 2.6 percent for delivery < 34 weeks, and 7.5 percent for birth weight < 2500 g. On univariate and multivariate analyses, there were no significant differences in any outcome between the 293 women with inflammation and the 284 women without inflammation on Papanicolaou smear. Results were unchanged when the analysis was limited to the 412 women who received no antibiotics during pregnancy. Among the 38 women with a history of preterm labor or preterm delivery, those with cervical inflammation had a higher rate of preterm labor than those without inflammation. CONCLUSIONS: In the sample as a whole, there was little evidence that findings of inflammation on Papanicolaou smear constituted a risk factor for preterm labor or preterm delivery. The data suggest that inflammation could be associated with an increased risk in a subgroup of women at higher risk by virtue of their obstetric history.
Adult↗
Comparison of nifedipine and ritodrine for the treatment of preterm labor.
Treatment of preterm labor with beta-sympathomimetics has been questioned because of the many maternal and fetal complications associated with its use. Nifedipine, a calcium antagonist, has been shown to suppress uterine activity in vitro and in vivo. A randomized prospective study was performed to compare the efficacy of nifedipine to ritodrine in the suppression of preterm labor. Data obtained from 42 women, of which 19 were randomized to the ritodrine group and 23 to the nifedipine group, were analyzed. Ritodrine and nifedipine proved to be equally effective in the suppression of preterm labor. However, the nifedipine group had fewer maternal and fetal complications.
Adult↗
Transforming growth factor-beta opposes the stimulatory effects of interleukin-1 and tumor necrosis factor on amnion cell prostaglandin E2 production: implication for preterm labor.
OBJECTIVE: In preterm labor increased concentrations of interleukin-1 and tumor necrosis factor are present in amniotic fluid. These cytokines may promote labor by stimulating the production of prostaglandins by intrauterine tissues. In many biologic processes, transforming growth factor-beta modifies the actions of cytokines. We studied the effect of transforming growth factor-beta on the cytokine-induced prostaglandin E2 production by amnion cells. STUDY DESIGN: Human amnion cells in monolayer culture were treated with interleukin-1, tumor necrosis factor, or vehicle in the presence or absence of transforming growth factor-beta. The prostaglandin E2 production was measured. RESULTS: Transforming growth factor-beta decreased the interleukin-1- or tumor necrosis factor-induced prostaglandin E2 production by 70% to 80% and the basal prostaglandin E2 synthesis by 27%. The synergistic stimulation of prostaglandin E2 production by the combination of interleukin-1 with tumor necrosis factor was inhibited by 80% in cells treated with transforming growth factor-beta. Transforming growth factor-beta 1, -beta 2, and -beta 1,2 were equipotent. CONCLUSION: Transforming growth factor-beta suppresses the cytokine-induced prostaglandin E2 production by amnion cells and may be an important factor in maintaining pregnancy in the face of labor-promoting cytokines.
Amnion↗
Endothelin-1,2 levels are increased in the amniotic fluid of women with preterm labor and microbial invasion of the amniotic cavity.
The purpose of this study was to determine the effect of gestational age, labor, and microbial invasion of the amniotic cavity on amniotic fluid concentrations of endothelin-1,2. Amniotic fluid was retrieved by amniocentesis from 148 women: patients at term with and without labor, patients with preterm labor with and without intraamniotic infection, and women in the second trimester of pregnancy. Endothelin-1,2 was measured by a sensitive and specific radioimmunoassay. Immunoreactive endothelin-1,2 was detectable in all samples of human amniotic fluid. Advancing gestational age and spontaneous term labor did not result in changes in amniotic fluid concentrations of endothelin-1,2. Women with preterm labor and positive amniotic fluid cultures for microorganisms had higher amniotic fluid concentrations of endothelin-1,2 than did those without microbial invasion of the amniotic cavity (p less than 0.05). These results support a role for endothelins in the mechanisms responsible for preterm delivery associated with intraamniotic infection.
Adult↗
Serum magnesium levels in pregnancy and preterm labor.
Pregnancy is marked by a state of hypomagnesemia. The serum magnesium level shows no gestational dependence (mean, 1.79 +/- 0.44 mg/dl) until 33 weeks, at which point it continuously declines. Serum magnesium is not depressed further with the onset of labor at term. Patients in preterm labor have a significantly depressed serum magnesium level (mean, 1.60 +/- 0.46 mg/dl; 21 to 33 weeks; p less than 0.0005). This level was not dependent on whether the etiology for the preterm labor was premature rupture of the membranes (PROM), twin gestation, abruption, placenta previa with bleeding, or chorioamnionitis. With PROM, the serum magnesium level was not depressed prior to the initiation of preterm labor. However, observation of hypomagnesemia for this and other etiologies just prior to the initiation of preterm labor were not available. Possible mechanisms by which hypomagnesemia induces uterine irritability are explored, including inhibition of adenyl cyclase with resultant increase in cytoplasmic calcium levels. Patients with diabetes mellitus appeared to have slightly reduced serum magnesium levels, but the results were not statistically significant. Magnesium levels in patients with preeclampsia were not significantly different from controls. Hypomagnesemia (magnesium 1.4 mg/dl or less) may be a marker for true preterm labor.
Calcium↗
Treatment of preterm labor with the beta-adrenergic agonist ritodrine.
BACKGROUND: Beta-adrenergic agonists are commonly used to arrest premature labor. Although treatment of preterm labor with these agents can delay delivery by 24 to 48 hours, the potential risks and benefits to the mother and infant before and after delivery have not been adequately assessed. METHODS: We randomly assigned 708 women with preterm labor at six hospitals to receive an intravenous infusion of either the beta-adrenergic agonist ritodrine (n = 352) or placebo (n = 356). Assignment was made with stratification according to four categories of gestational age (20 to 23 weeks, 24 to 27 weeks, 28 to 31 weeks, and 32 to 35 weeks). The primary objective was to assess the effect of ritodrine on perinatal mortality. Secondary objectives were the evaluation of the causes of perinatal death, the extent to which delivery was delayed with ritodrine, and the effects on birth weight, maternal morbidity, neonatal morbidity, and infant morbidity at 18 months of postnatal age, corrected for preterm delivery. RESULTS: Among the 771 infants born to the women in the study (including 63 pairs of twins), there were 23 deaths (6.1 percent) in the ritodrine group and 25 deaths (6.4 percent) in the placebo group (event-rate difference, -0.3 percent; 95 percent confidence interval, -3.7 percent to 3.1 percent). There was no difference between the groups in the extent of delay of delivery, the incidence of delivery before 37 weeks' gestation, the proportion of babies weighing less than 2500 g, or measures of neonatal morbidity. Maternal morbidity (such as chest pain and cardiac arrhythmias) occurred more frequently but not exclusively in the ritodrine group. One infant born to a woman in the ritodrine group and five infants born to women in the placebo group had cerebral palsy (P = 0.09). There was a slight but not significant trend toward an improved score on the Bayley Psychomotor Development Index at 18 months of age among the infants of the ritodrine-treated women. CONCLUSIONS: We found that the use of ritodrine in the treatment of preterm labor had no significant beneficial effect on perinatal mortality, the frequency of prolongation of pregnancy to term, or birth weight.
Birth Weight↗
Women's views of the preterm labor experience.
This study used a naturalistic approach to describe the childbearing woman's views of her preterm labor and delivery experience. Specifically, the aim was to identify how women describe, interpret, and manage preterm labor and subsequent preterm or term delivery. The views of 20 women who were hospitalized for preterm labor (before 37 weeks) were documented with semistructured, tape-recorded, in-depth interviews during their hospitalization for preterm labor and after delivery. Qualitative data analysis focused on the process of becoming a preterm labor patient and on living with a diagnosis of preterm labor. Women either waited for a period of time before seeking care or sought care immediately for the symptoms they were experiencing. Women interpreted the experience by identifying causes of preterm labor and by worrying about the outcome for the baby. Managing preterm labor required extensive, moderate, or limited changes in their lives. Women who delivered at term appeared to have more tangible help than those who delivered preterm. A better understanding of women's preterm labor experiences will provide clues to nurses on how to improve the care they provide.
Adolescent↗
Effect of maternal carbon dioxide inhalation on human fetal breathing movements in term and preterm labor.
Induced maternal hypercapnia is a potent stimulus to fetal breathing movements in nonlaboring pregnant women. To determine the effect of maternal CO2 administration on fetal breathing movements during spontaneous labor, 14 healthy pregnant volunteers at term and 34 in preterm labor were recruited. If fetal breathing movements were markedly decreased or absent, the subjects were administered a prepared gas mixture of 3% CO2 in air. In term labor and in true preterm labor, fetal breathing movements were markedly decreased and could not be induced by maternal hypercapnia. Among women with suspected preterm labor, initial absence of fetal breathing movements and failure to evoke this response by maternal hypercapnia predicted delivery within 48 hours with a sensitivity of 80% and specificity of 95.5%. Induced maternal hypercapnia fails to stimulate fetal breathing movements in true term and preterm labor and may assist in distinguishing between true and false preterm labor.
Administration, Inhalation↗
A study of the epidemiology of preterm labor.
A case-control study was designed in order to identify risk factors associated with preterm labor. All cases fulfilling the criteria of eligibility as preterm labor and attending the Ain Shams University Maternity Hospital during the period from January 1991 to June 1991 were included in the study. In the meanwhile, all women delivering after the 37th week of gestation during that period and in the same hospital and matched according to age (+/- 5 years) were included as the control group. Two hundred and thirty four cases and 216 controls were included in the study. An interview was performed to fill an epidemiologic and clinical questionnaire. Results showed that the lower the socioeconomic standard, the more the risk for preterm labor (p < 0.05), smoking whether active or passive is associated with preterm labor (p < 0.001), threatened or induced abortion, unwanted pregnancy, psychological trauma and surgical intervention during current pregnancy are associated with preterm labor (p < 0.001). History of preterm labor is associated with the present condition (p < 0.001). Anemia, hypertension, body weight less than 70 kgm are associated with preterm labor (p < 0.001).
Adult↗
Elevated maternal plasma corticotropin-releasing hormone levels in pregnancies complicated by preterm labor.
OBJECTIVES: We investigated whether maternal plasma levels of the placental hormone corticotropin-releasing hormone are elevated in pregnancies complicated by preterm labor. STUDY DESIGN: Mean maternal corticotropin-releasing hormone levels were studied in women who met specific criteria for preterm labor and in women with normal pregnancies. Levels were also compared in the latent and active phases during term labor. RESULTS: In pregnancies complicated by preterm labor, maternal corticotropin-releasing hormone levels were higher than in normal pregnancies; this elevation occurred before labor was diagnosed clinically (p less than 0.05). When preterm labor was associated with infection, the mean levels were not elevated. Mean plasma levels were similar in latent and active phases during labor at term. CONCLUSION: Maternal plasma corticotropin-releasing hormone levels are elevated in association with preterm labor. This elevation does not appear to be due to labor itself and may reflect an early activation of the placenta before the onset of preterm labor.
Corticotropin-Releasing Hormone↗
Listeria monocytogenes. The role of transabdominal amniocentesis in febrile patients with preterm labor.
Two women with preterm labor and intraamniotic infection with Listeria Monocytogenes are presented. In both patients, the prenatal diagnosis of Listeriosis was made by transabdominal amniocentesis. The immediate prominent observation was meconium staining of the amniotic fluid. We propose that an amniocentesis should be performed in women with premature labor and fever. If the amniotic fluid is meconium stained and the Gram stain examination reveals Gram positive rods, Listeria Monocytogenes should be suspected and the patient should be treated accordingly until the culture results are obtained.
Adult↗