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PubMed2000

Risk factors for symptomatic uterine rupture during a trial of labor: the 1990s.

The purpose of this study is to identify pregnancy and labor factors that place women at increased risk for symptomatic uterine rupture during trial of labor following cesarean section. The study population consisted of 16 women with uterine rupture after a trial of labor who were compared with 32 women without uterine rupture after a trial of labor. Using a case-control study design with a 1:2 match, we examined risk factors that might be associated with an increased risk of uterine rupture. Cases were more likely to have an induction of labor with the use of oxytocin and/or amniotomy (56 vs. 34%) and more likely to undergo augmentation with oxytocin (25 vs. 19%) in comparison with controls. In addition, cases were more likely to be given oxytocin (for either induction or augmentation) (75 vs. 50%) and cervical ripening agents (31 vs. 9%) versus controls. Neonates born after uterine rupture had a higher rate of significant acidosis (pH < 7.0, 57 vs. 0%, p = 0.0002) and lower Apgar scores. There was a significantly higher risk of maternal infection (36 vs. 3%, p = 0.003), transfusion (13 vs. 0%, p = 0.03), and longer length of stay in patients with uterine rupture. There is a trend for increased use of augmentation and induction agents to be associated with uterine rupture. Serious maternal and fetal morbidities are increased following uterine rupture.

Acidosis↗
PubMed1995

Labor induction in patients with previous cesarean section.

To determine the efficacy and safety of labor induction in patients previously delivered by at least one low transverse cesarean section, a retrospective review was done at a single tertiary perinatal center, the University of Florida Health Science Center, Jacksonville. All patients with a previous cesarean section who required labor induction from 1988 until the end of 1992 were identified. Duration and outcome of labor induction, including mode of delivery, maternal and perinatal morbidity, and birth trauma, were evaluated. Of 160 patients with a previous cesarean, 50 (31.3%) had a repeat operation compared to 18 (11.2%) in the no previous cesarean group (p = 0.001, odds ratio = 3.59; 95% confidence interval, 1.98, 6.49). Women in the cesarean group had a higher incidence of operative vaginal deliveries, prolonged duration of the first and second stages of labor, rate and maximum dose of oxytocin infusion. One patient in the previous cesarean group experienced uterine rupture. There was no difference in the rate of infants with low 5-minute Apgar scores or with cord pH values less than 7.20. Labor induction in women with previous low transverse cesarean sections results in an acceptable rate of vaginal delivery and appears safe for both mother and fetus.

Adult↗
PubMed2001

Amniotic fluid concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 during pregnancy and labor.

OBJECTIVE: This study was undertaken to determine whether obstetric factors affect the concentrations of matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 in the amniotic fluid. STUDY DESIGN: We prospectively collected amniotic fluid samples from 109 women at various stages of pregnancy and labor and determined matrix metalloproteinase 9 and tissue inhibitor of metalloproteinase 1 concentrations by means of enzyme-linked immunosorbent sandwich assay systems. With multiple regression analysis we evaluated relationships between amniotic fluid matrix metalloproteinase 9 concentration and tissue inhibitor of metalloproteinase 1 concentration and the following factors: gestational age, presence of labor, cervical dilatation, membrane status, presence of clinical chorioamnionitis, and microbial colonization of the amniotic fluid. RESULTS: The detectable presence of amniotic fluid matrix metalloproteinase 9 was independently associated with intra-amniotic infection, labor, cervical dilatation, and spontaneous rupture of membranes. Chorioamnionitis and amniotic fluid matrix metalloproteinase 9 concentrations were correlated with tissue inhibitor of metalloproteinase 1 levels. CONCLUSIONS: Intra-amniotic infection, advanced labor, and rupture of membranes before the onset of labor were independently associated with the presence of matrix metalloproteinase 9 in the amniotic fluid. Both pathologic and physiologic processes appear to produce shifts in the balance between degradation and synthesis of the extracellular matrix.

Amniotic Fluid↗
PubMed1998

Increased expression of the rat myometrial oxytocin receptor messenger ribonucleic acid during labor requires both mechanical and hormonal signals.

We investigated the expression of the mRNA encoding the oxytocin receptor (OTR) in rat myometrium throughout gestation and its regulation by progesterone and mechanical stretch. Using a semiquantitative reverse transcription-polymerase chain reaction approach, OTR mRNA was found to increase abruptly at the onset of spontaneous labor at term. Progesterone (4 mg/day) starting on Day 20 of gestation blocked this increase. Ovariectomy on Day 17 induced preterm labor 96 h after surgery and a significant increase in myometrial OTR mRNA levels 48 and 96 h after surgery. Both preterm labor and the rise in myometrial OTR expression were blocked by progesterone. To investigate the effects of stretch on myometrial OTR mRNA expression, unilaterally pregnant rats underwent either sham operation or placement of a tube in the nongravid uterine horn to distend the myometrium. On Day 20, stretch had no effect on OTR expression in the nongravid horns. During labor, OTR mRNA was highly expressed in the gravid horns as well as the nongravid stretched horns. In contrast, the level remained low in the nongravid unstretched horns. These results indicate that expression of rat myometrial OTR mRNA during pregnancy and labor is regulated by coordinated interactions between mechanical and endocrine signals.

Animals↗
PubMed1999

Effect of labor induction on the expression of oxytocin receptor, cytochrome P450 aromatase, and estradiol receptor in the reproductive tract of the late-pregnant ewe.

UNLABELLED: In this study, we investigated the timing of changes in aromatase, estradiol receptor, and oxytocin receptor expression in ovine uterine and placental tissues before parturition. Labor was induced by betamethasone injection into the fetus on Days 130-132 of pregnancy. Tissue samples were collected at injection and then every 14 h until labor (56 h) from four ewes at each time point. Samples were analyzed for aromatase, estradiol receptor, and oxytocin receptor expression by in situ hybridization; for oxytocin binding to its receptor using a specific antagonist; and for estradiol receptor quantitation by immunocytochemistry. Aromatase mRNA expression increased by 14 h postinjection (p < 0.02) in the fetal villi and remained high until labor. Expression of estradiol and oxytocin receptor mRNAs was unchanged in myometrium but increased in the endometrial luminal epithelium by 28 h (p < 0.05) and remained high until labor. Estradiol receptor protein concentration increased modestly at labor while oxytocin receptor binding in the luminal epithelium changed in parallel to the mRNA concentration. IN CONCLUSION: 1) induction of aromatase may facilitate the expression of endometrial estradiol and oxytocin receptors in the placentome, 2) changes in endometrial rather than myometrial oxytocin receptor may be important in inducing parturition, and 3) the transcription of estradiol receptor and oxytocin receptor in the uterine epithelium are positively correlated during parturition.

Animals↗
PubMed1999

Differential regulation of prostaglandin EP and FP receptors in pregnant sheep myometrium and endometrium during spontaneous term labor.

In the present study, we characterized the mRNA abundance of prostaglandin E(2) receptor subtypes (EP1 and EP3, which stimulate excitatory responses; EP2 and EP4, which stimulate inhibitory responses) and the FP receptor in pregnant sheep myometrium and endometrium in relation to parturition. Myometrial and endometrial poly(A) RNA was extracted from control ewes at 143-147 days gestational age (dGA, n = 6) and from ewes in spontaneous term labor at 145-147 dGA (n = 6), and was subjected to Northern blot analysis for FP, EP1, EP2, EP3, and EP4 mRNA. Myometrial EP3, EP4, and FP mRNA abundance increased during labor (P<0.05); EP2 mRNA did not change. EP1 mRNA was not detectable in the myometrium. Endometrial EP2 and EP4 mRNA remained unchanged during labor. EP3 mRNA was expressed at a very low level, and EP1 and FP mRNA were not detected in endometrium in any animals studied. In conclusion, there is differential expression in myometrium and endometrium of EP subtypes and FP receptor in relation to labor. Increases in EP3 and FP, together with increased prostaglandin production from intrauterine tissues, may lead to the switch in the myometrial contraction pattern that occurs during labor. These differences within and between myometrium and endometrium may result from different anatomical location, such as longitudinal or circular layers of myometrium, or vascular location.

Animals↗
PubMed2000

Labor induction.

Labor induction has become commonplace in modern obstetrics. The increasing rate of labor induction has probably played a role in the increased rate of cesarean delivery observed in the United States during the past few decades. Clearly, the favorability of the cervix has a substantial impact on the potential success of any labor induction. Induction in the setting of an unfavorable cervix can result in prolonged induction, prolonged hospitalization, failed induction, and an increased cesarean delivery rate. In this modern era of healthcare reform and cost containment, the identification of therapeutic strategies to enhance the success and cost-effectiveness of labor induction are of great interest. Ongoing research is needed to advance our knowledge of the mechanisms of parturition and cervical ripening in order to direct interventions for labor induction more effectively.

Cervical Ripening↗
PubMedDate not supplied

Acupuncture during labor can reduce the use of meperidine: a controlled clinical study.

OBJECTIVE: To evaluate the effectiveness of acupuncture as an analgesic during labor. DESIGN: A randomized, unblinded, controlled study. SETTING: A labor ward in a University Hospital. PATIENTS: Parturients at term. INTERVENTIONS: One group received acupuncture (N = 106); another did not (N = 92). A second control group (N = 92), drawn from the labor ward protocol, consisted of patients who met the eligibility criteria for the study and were matched to the "no acupuncture" group by parity, but who had not been offered the opportunity to take part. Outcome measure "effectiveness of acupuncture" was measured by the requirement for use of meperidine. RESULTS: Meperidine was given to 11% of the acupuncture group, 37% of the no acupuncture group (P < 0.0001), and 29% of the control group. The use of other analgesics was also lower in the acupuncture group. Patient satisfaction was high: 89 of 103 patients asked said they would want acupuncture during another labor. CONCLUSIONS: Acupuncture during labor reduced the requirement for other painkillers and has high patient satisfaction in this randomized, unblinded, controlled study.

Acupuncture Analgesia↗
PubMed1988

Does the onset of spontaneous labor at term influence fetal biophysical test parameters?

Recent data suggest that fetal breathing movement incidence declines while fetal heart rate (FHR) and body movement incidence do not change within 72 hours of spontaneous term labor. We conducted a retrospective study to determine whether the length of time from testing to spontaneous labor onset could influence these biophysical test parameters. Eighty-one normal term fetuses underwent 60-minute tests 1-40 days before the onset of spontaneous labor: 41 were tested within 7 days of labor (19 within 3 days and 22 within 4-7 days) and 40 were tested more than 7 days before labor. We simultaneously acquired and analyzed FHR baseline, frequency of accelerations between ten to 14 beats per minute and more than 15 beats per minute in amplitude, percent of time spent in breathing and moving, and fetal breath rate. These biophysical parameters were not significantly different between the groups, implying that they may continue to provide clinically useful information in the prelabor period.

Female↗
PubMed1994

Tissue inhibitor of metalloproteinases: serum levels during pregnancy and labor, term and preterm.

OBJECTIVE: To determine the levels in serum of tissue inhibitor of metalloproteinases (TIMP) in pregnancy and to examine the possibility of a time course in relation to parturition, both term and preterm. METHODS: Serum tissue inhibitor of metalloproteinases was measured using an enzyme-linked immunosorbent assay. A cross-sectional study was conducted in 333 women during pregnancy, labor, and the postpartum period and in 27 nonpregnant volunteers. Longitudinal data were obtained from 22 women who provided a sample at term, during labor, and in the postpartum period. RESULTS: In uncomplicated pregnancies, serum TIMP levels were low from the onset of pregnancy until 37 weeks' gestation, in comparison to levels in nonpregnant women (P < .001). During the final weeks of pregnancy, levels rose and at 37-42 weeks were similar to nonpregnant levels. The levels did not change with the onset of labor. Serum concentrations of TIMP obtained during preterm labor were elevated compared to a control group of patients at a similar gestation who subsequently delivered at term (P < .01). Serum TIMP levels were significantly higher during the postpartum period than at all other times (P < .001). CONCLUSIONS: Changes in serum TIMP levels during and after pregnancy may parallel the remodeling of the extracellular matrix that takes place throughout this period. Further work is necessary to evaluate the prognostic value of TIMP for preterm labor.

Cross-Sectional Studies↗
PubMed2006

Membrane sweeping at initiation of formal labor induction: a randomized controlled trial.

OBJECTIVE: To determine the benefit of membrane sweeping at initiation of labor induction in conjunction with formal methods of labor induction. METHODS: Two hundred seventy-four women at term with a singleton fetus in cephalic presentation and intact membranes were randomly assigned to receive membrane sweeping or no membrane sweeping at initiation of formal labor induction with either dinoprostone pessary or amniotomy. Outcome measures included mode of delivery, induction-to-delivery interval, dinosprostone dose, any oxytocin use and duration of oxytocin use in labor, visual analog score for pain associated with sweeping, and visual analog score for satisfaction with the birth process. RESULTS: Two hundred sixty-four women (136 sweep and 128 no sweep) had their data analyzed. Ten women (4 sweep and 6 no sweep) were excluded because of exclusion criteria infringements. Swept women had higher spontaneous vaginal delivery rate (69% compared with 56%, P = .041), shorter induction to delivery interval (mean 14 compared with 19 hours, P = .003), fewer that required oxytocin use (46% compared with 59%, P = .037), shorter duration of oxytocin infusion (mean 2.6 compared with 4.3 hours, P = .001) and improved visual analog score for birth process satisfaction (mean 4.0 compared with 4.7, P = .015). The reduction in dinoprostone dose used (mean 1.2 compared with 1.3, P = .082) was not significant. Postsweeping visual analog score for pain (mean 4.7 compared with 3.5, P < .001) was significantly increased. CONCLUSION: Membrane sweeping at initiation of labor induction increased the spontaneous vaginal delivery rate, reduced oxytocic drug use, shortened induction to delivery interval, and improved patient satisfaction. LEVEL OF EVIDENCE: I.

Adult↗
PubMed2006

Risk of uterine rupture with a trial of labor in women with multiple and single prior cesarean delivery.

OBJECTIVE: To determine whether the risk for uterine rupture is increased in women attempting vaginal birth after multiple cesarean deliveries. METHODS: We conducted a prospective multicenter observational study of women with prior cesarean delivery undergoing trial of labor and elective repeat operation. Maternal and perinatal outcomes were compared among women attempting vaginal birth after multiple cesarean deliveries and those with a single prior cesarean delivery. We also compared outcomes for women with multiple prior cesarean deliveries undergoing trial of labor with those electing repeat cesarean delivery. RESULTS: Uterine rupture occurred in 9 of 975 (0.9%) women with multiple prior cesarean compared with 115 of 16,915 (0.7%) women with a single prior operation (P = .37). Multivariable analysis confirmed that multiple prior cesarean delivery was not associated with an increased risk for uterine rupture. The rates of hysterectomy (0.6% versus 0.2%, P = .023) and transfusion (3.2% versus 1.6%, P < .001) were increased in women with multiple prior cesarean deliveries compared with women with a single prior cesarean delivery attempting trial of labor. Similarly, a composite of maternal morbidity was increased in women with multiple prior cesarean deliveries undergoing trial of labor compared with those having elective repeat cesarean delivery (odds ratio 1.41, 95% confidence interval 1.02-1.93). CONCLUSION: A history of multiple cesarean deliveries is not associated with an increased rate of uterine rupture in women attempting vaginal birth compared with those with a single prior operation. Maternal morbidity is increased with trial of labor after multiple cesarean deliveries, compared with elective repeat cesarean delivery, but the absolute risk for complications is small. Vaginal birth after multiple cesarean deliveries should remain an option for eligible women. LEVEL OF EVIDENCE: II-2.

Adult↗
PubMed2004

Markedly elevated levels of inflammatory cytokines in maternal serum and peritoneal washing during arrested labor.

BACKGROUND: The role of inflammatory cytokines in the pathophysiology of arrested labor is currently unknown. We measured levels of inflammatory cytokines in maternal serum and peritoneal washings in arrested first stage of labor to assess the possible involvement of these mediators in this obstetric disorder. METHODS: This was a prospective, case-control study involving 15 women who underwent cesarean section for arrested cervical dilatation (group I), 15 controls who were operated during active labor for nonreassuring fetal heart-rate tracing (group II) and 15 controls who were operated electively (group III). Blood samples were drawn from all women shortly before the operation. The presence of peritoneal fluid was assessed and peritoneal washings were obtained during the operation. All samples were assayed for the inflammatory cytokines interleukin (IL)-1beta, IL-6, IL-8 and soluble IL-2 receptor (sIL-2R) by solid-phase enzyme-linked immunosorbent assay (ELISA). RESULTS: All women from group I and one patient (6.7%) from group II had some degree of peritoneal fluid accumulation, while none from group III had any. Serum samples from group I contained significantly higher IL-1beta, IL-6, IL-8 and IL-2R levels than both control groups. Peritoneal washings from group I contained significantly higher IL-1beta, IL-6 and IL-8 but similar IL-2R levels. CONCLUSIONS: Arrested first stage of labor is associated with peritoneal fluid accumulation and increased levels of inflammatory cytokines in both serum and peritoneal fluids. Inflammatory cytokines may therefore be involved in the pathophysiology of arrested labor.

Adult↗
PubMed2006

Prolonged second stage of labor and risk of adverse maternal and perinatal outcomes: a systematic review.

BACKGROUND: Safe and effective management of the second stage of labor presents a clinical challenge for laboring women and practitioners of obstetric care. This systematic review was conducted to evaluate evidence for the influence of prolonged second stage of labor on the risk of selected adverse maternal and neonatal outcomes. METHODS: Articles were searched using PubMed, Cochrane Library, and CINAHL from 1980 until 2005. Studies were included according to 3 criteria: if they reported duration of the second stage of labor, if they reported maternal and/or neonatal outcomes in relation to prolonged second stage, and if they reported original research. RESULTS: Our systematic review found evidence of a strong association between prolonged second stage and operative delivery. Although significant associations with maternal outcomes such as postpartum hemorrhage, infection, and severe obstetric lacerations were reported, inherent limitations in methodology were evident in the studies. Recurrent limitations included oversimplified categorization of second stage, inconsistency in study population characteristics, and lack of control of confounding factors. No associations between prolonged second stage and adverse neonatal outcomes were reported. CONCLUSIONS: The primary findings of our review indicated that most of the studies are flawed and do not answer the important questions for maternity caregivers to safely manage prolonged second stage. Meanwhile, approaches for promoting a normal second stage of labor are available to caregivers, such as maternal positioning and pain relief measures and also promoting effective pushing technique.

Adult↗
PubMedDate not supplied

A descriptive analysis of involuntary bearing-down efforts during the expulsive phase of labor.

A series of descriptive studies was carried out to characterize maternal respiration, type of bearing-down efforts, vocalization, and behavior; describe the obstetric conditions and intrauterine pressure associated with the bearing-down reflex; and describe the duration of second stage, fetal heart rate, and neonatal outcomes when women bear down spontaneously. Thirty-one healthy nulliparous women who had received no formal childbirth education were neither directed nor instructed to bear down with contractions. The women were supported in their involuntary bearing-down efforts throughout the second stage of their labors while the above features of their labor were recorded. The findings suggest that labor progress is adequate and fetal outcome is good when the management of the expulsion phase of labor encourages maternal pushing that is complementary with the involuntary bearing-down reflex rather than sustained breath-holding. These findings support the necessity for further research regarding the bearing-down techniques used during labor.

Adolescent↗
PubMed2001

Methods and devices for the management of term and preterm labor.

In this review, we outline studies showing that the uterus (myometrium) and cervix pass through a conditioning step in preparation for labor. This step is not easily identifiable with present methods designed to assess the uterus or cervix. In the uterus, this seemingly irreversible step consists of changes in the electrical properties that make muscle more excitable and responsive and produce forceful contractions. In the cervix, the step consists of softening of the connective tissue components. Progesterone and nitric oxide appear to have important roles in these processes. The progress of labor can be assessed noninvasively using electromyographic (EMG) signals from the uterus (the driving force for contractility) recorded from the abdominal surface. Uterine EMG bursts detected in this manner characterize uterine contractile events during human and animal pregnancy. A low uterine EMG activity, measured transabdominally throughout most of pregnancy, rises dramatically during labor. EMG activity also increases substantially during preterm labor in humans and rats and may be predictive of preterm labor. A quantitative method for assessing the cervix is also described. A collascope estimates cervical collagen content from a fluorescent signal generated when collagen crosslinks are illuminated with an excitation light of about 340 nm. The system has proved useful in rats and humans at various stages of pregnancy and indicates that cervical softening occurs progressively in the last one-third of pregnancy. In rats, collascope readings correlate with resistance measurements made in the isolated cervix, which may help to assess cervical function during pregnancy and indicate controls and treatments.

Delivery, Obstetric↗
PubMed1999

Case series of labor induction in twin gestations with an Intrauterine Balloon catheter.

The efficacy and safety of labor induction using an intrauterine balloon catheter in twin pregnancies has been evaluated. During the study period (1992-1997), labor was induced at 36-42 weeks in 17 twin gestations. Labor induction was indicated for preeclampsia (n = 10), birth weight discordance (n = 3), suspected fetal distress (n = 2) and postdates (n = 2). Twin A was in vertex presentation in all cases. An intrauterine balloon catheter was inserted transcervically followed by augmentation whenever required. Vaginal delivery was achieved in 15 (88.2%) patients. The mean interval from balloon insertion to delivery was 17.05 h, with 80% deliveries occurring within 24 h of catheter insertion and 80% occurring within 12 h of catheter expulsion. Birth weight was 2,514+/-244 and 2,421+/-367 g for twin A and B, respectively. Oxytocin was required in 4 patients. Postpartum hemorrhage was noted in 1 patient. One patient with no progress of labor and 1 with suspected intrapartum fetal distress required cesarean section. All neonates had a 5-min Apgar score of 10. The data suggest that an intrauterine balloon catheter appears to be safe and effective to induce labor in twin gestations.

Adult↗
PubMed2002

Induction of labor in grand multiparous women and previous cesarean section: is it safe?

OBJECTIVE: To compare the outcome of induced and spontaneous labor in grand multiparous women with one previous lower segment cesarean section, so that the safety of labor induction could be assessed. METHOD: In 56 women labor was induced and their outcomes were compared with those of 177 women with spontaneous labor. All women were multiparous and had had one previous cesarean section. RESULTS: There were no significant differences in the incidences of 1- and 5-min Apgar scores, congenital malformation, cesarean section rates and uterine scar dehiscence or uterine rupture. There were 4 cases of intrauterine fetal death in the induction group, but no case of intrapartum or early neonatal death in the 2 groups. In the study group, 80.4% of the women delivered vaginally compared with 84.3% in the control group. CONCLUSION: In this moderate-sized study, we may conclude that when there is no absolute indication for repeating cesarean section, induction of labor may be a safe option in these high-risk women.

Adult↗