[Electric stimulation of the uterus in flat form of the amniotic sac].
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Amnion↗
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Unengaged vertex in nulliparous women in active labor. A risk factor for cesarean delivery.
OBJECTIVE: To compare the route of delivery among nulliparous parturients with and without an engaged vertex in the early, active phase of labor. METHODS: Prospectively, the position of the fetal head was ascertained among nulliparous women at 37 weeks' gestation or more in early, active labor (cervical dilation > or = 4 cm with adequate contractions). Sixteen variables, including maternal demographics, obstetric complications and intrapartum course, were examined using chi 2 and logistic regression analysis. RESULTS: Among the 77 patients, 33 (42.8%) had an unengaged vertex and 44 (57.2%) had an engaged vertex in active labor. Of the 22 cesarean deliveries for arrest disorder, 2 were in the engaged and 20 in the unengaged group (P < .001). The mean birth weight was similar among those who had vaginal (3,211 +/- 416 g) and cesarean delivery (3,400 +/- 489 g, P = .08). Univariate analysis indicated that chorioamnionitis (relative risk [RR] 2.6, 95% confidence interval [CI] 1.4-4.9) and unengaged vertex (RR 13.3, CI 3.3-53.0) were associated with cesarean delivery for arrest disorders. When entered into a multiple logistic model, only unengagement was a risk factor for cesarean delivery. The following were not associated with cesarean delivery: maternal demographics, gestational age, estimate of fetal weight, presence or absence of meconium, preeclampsia, diabetes mellitus, private obstetric care or use of epidural anesthesia. CONCLUSION: Among nulliparous parturients, an unengaged vertex is a significant risk factor for cesarean delivery for arrest disorders.
Adolescent↗
Initiation of labor.
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Adrenal Cortex Hormones↗
[Relationship between labor prognosis and characteristics of the preliminary period].
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Female↗
Effect of prophylactic outpatient administration of fenoterol on the time of onset of spontaneous labor and fetal growth rate in twin pregnancy.
A double-blind trial was conducted on outpatients with twin gestations to assess the effect of prophylactic administration of fenoterol on the fetal growth rate and the timing of the spontaneous onset of labor. No significant differences could be shown between the fenoterol-treated group of patients and the control group given a placebo. It is concluded that prophylactic administration of fenoterol does not have a significant effect upon the incidence of preterm labor or growth retardation in twin pregnancy.
Clinical Trials as Topic↗
The kinetics of blood coagulability: fibrinolytic and kallikrein-kinin system at the onset and during labor.
The relationship between the kallikrein-kinin system, the coagulation system, and the fibrinolytic system was evaluated on 58 patients during pregnancy, labor and puerperium. Also included in this study were 7 patients with premature placental separation. The most prominent changes were those in the kallikrein-kinin system. After the onset of labor, prekallikrein decreases rapidly which may trigger changes in the blood coagulation and fibrinolytic system. The three systems have a close interrelationship possibly affecting uterine contractility during labor and delivery.
Adult↗
Maternal intravenous administration of long chain n-3 polyunsaturates to the pregnant ewe in late gestation results in specific inhibition of prostaglandin h synthase (PGHS) 2, but not PGHS1 and oxytocin receptor mRNA in myometrium during betamethasone-induced labor.
OBJECTIVES: Both the onset of labor and time to delivery during betamethasone-induced delivery are delayed by omega-3 polyunsaturated fatty acid (PUFA) administration to pregnant sheep. That fatty acid also inhibits the labor-related increase in maternal plasma estradiol and maternal and fetal prostaglandin E(2). To evaluate the mechanism of inhibition of prostaglandin production and delay of onset of labor and time of delivery in PUFA-treated sheep, we determined the effect of PUFA on myometrial prostaglandin H synthase (PGHS) 1 and 2 and oxytocin receptor mRNA levels in betamethasone-induced labor. METHODS: At 124 days' gestation, a 20% emulsion of either intralipid (IL, n = 6) or PUFA (n = 6) was infused continuously (3 mL/kg per day) intravenously (IV) to the ewe. At 125 days' gestation, betamethasone was administered IV (10 microg/h over 48 hours) to fetuses of both intralipid- and PUFA-treated ewes. Myometrium was collected at necropsy either during betamethasone-induced labor as evaluated by myometrial electromyography or within 5 days of the termination of betamethasone infusion, if delivery did not occur after fetal betamethasone infusion. Total myometrial RNA was analyzed by Northern blot for oxytocin receptor and PGHS1 and 2 mRNA normalized for 18s. RESULTS: Treatment with PUFA decreased myometrial PGHS2 mRNA but did not alter myometrial PGHS1 and oxytocin receptor mRNA after betamethasone administration. CONCLUSIONS: This finding provides a mechanism whereby PUFA delays betamethasone-induced delivery in sheep and suggests a potential role of PUFA as an effective tocolytic agent in human pregnancy.
Animals↗
Alterations in uterine sodium pump abundance may contribute to the onset and progression of term and preterm labor in mice.
OBJECTIVE: Other investigators have shown that reductions in active sodium pump units increase uterine contractility. Therefore, our goal was to determine whether uterine sodium pump abundance is decreased in mouse models of term and preterm labor. STUDY DESIGN: Mice were studied during the final one-third of pregnancy. Other pregnant mice had preterm labor induced with lipopolysaccharide and were studied at timed intervals thereafter. Uterine sodium pump alpha3-isoform messenger RNA and protein were measured. Data were analyzed by analysis of variance. RESULTS: Uterine sodium pump alpha3-isoform messenger RNA fell significantly from day 14 to day 18 and remained low on the day of birth. Uterine sodium pump alpha3-isoform protein levels decreased significantly also. In lipopolysaccharide-induced preterm labor, uterine sodium pump alpha3-isoform protein, but not messenger RNA, decreased significantly. CONCLUSION: Sodium pump alpha3-isoform protein levels decreased in uterus before term labor and lipopolysaccharide-induced preterm labor. These findings are similar to those in humans, which suggests that this mouse model may be useful in the study of the sodium pump in human pregnancy. Reductions in sodium pump number can increase uterine contractile force and may contribute to labor.
Animals↗
An increase in fetal plasma cortisol but not dehydroepiandrosterone sulfate is followed by the onset of preterm labor in patients with preterm premature rupture of the membranes.
OBJECTIVE: The role of steroid hormones in the control of human parturition has been a subject of debate. Activation of the fetal hypothalamic-pituitary-adrenal axis leading to an increase in plasma cortisol is followed by the onset of parturition in sheep. In contrast, androgens, specifically, dehydroepiandrosterone sulfate, have been implicated in the control of parturition in nonhuman primates. The purpose of this study was to determine the relationship between human fetal plasma cortisol and dehydroepiandrosterone sulfate and the onset of preterm labor in patients with preterm premature rupture of the membranes. STUDY DESIGN: Fetal blood sampling was performed in 51 patients with preterm premature rupture of membranes who were not in labor on admission. Amniotic fluid was cultured for aerobic and anaerobic bacteria and mycoplasmas. Corticosteroids had not been administered before fetal blood sampling. Cortisol and dehydroepiandrosterone sulfate were measured with sensitive and specific immunoassays. Analysis was conducted with nonparametric statistics and survival analysis. RESULTS: (1) Patients who went into spontaneous labor and delivered within 7 days of cordocentesis had a significantly higher median level of fetal plasma cortisol but not of dehydroepiandrosterone sulfate than those delivered after 7 days (for fetal plasma cortisol: median 8.35 [4.7 to 12.4] micrograms/dL vs median 4.75 [3.0 to 10.4] micrograms/dL, P <.0001; for fetal plasma dehydroepiandrosterone sulfate: median 154.4 [8.6 to 333.8] micrograms/dL vs median 194.6 [96.7 to 402.5] micrograms/dL, P =.09). (2) The cordocentesis-to-delivery interval was significantly shorter in patients with a fetal plasma cortisol value of >/=7 micrograms/dL (derived by receiver-operating characteristic curve analysis) than in those with fetal cortisol <7 micrograms/dL (median 49 [4 to 1849] hours vs median 325 [11 to 2590] hours, P <.001). (3) Fetal plasma cortisol, but not maternal cortisol, was an independent predictor of the duration of pregnancy after we adjusted for gestational age and the results of amniotic fluid culture (hazards ratio 2.9, P <.05). (4) There was a significant correlation between fetal plasma cortisol and fetal plasma interleukin-6 (r = 0.3, P <.05). (5) A strong relationship was found between the fetal plasma cortisol/dehydroepiandrosterone sulfate ratio and the interval to delivery (P <.005). CONCLUSION: An elevation in fetal plasma cortisol but not dehydroepiandrosterone sulfate was followed by the onset of spontaneous preterm labor in patients with preterm premature rupture of the membranes.
Adult↗
Labor induction after fetal death. A retrospective analysis.
OBJECTIVE: To describe the delivery outcomes in patients with stillborn infants after labor induction versus spontaneous onset of labor. STUDY DESIGN: A retrospective chart review was performed of singleton pregnancies complicated by fetal death over a three-year period when awaiting spontaneous onset of labor was a common practice. Exclusion criteria were prior multiple cesarean deliveries, placenta previa, preeclampsia or suspected abruptio placentae. Outcome measures included time spent in the labor and delivery unit and rates of maternal hemorrhagic morbidity and endomyometritis. RESULTS: Two hundred eight patients, 100 patients undergoing labor induction and 108 with spontaneous onset of labor, met the study criteria. Patients delivering after induction spent a longer time in the labor and delivery unit (13.7 versus 4.4 hours). The endomyometritis rate was higher in the spontaneous labor group (6% versus 1%). There were no differences in the frequency of postpartum hemorrhage, retained placenta or need for blood transfusion. CONCLUSION: Induction following diagnosis of fetal death is safe and may reduce maternal infectious morbidity.
Adult↗
The course of labor after endurance exercise during pregnancy.
This study was designed to test the hypothesis that continuation of a regular running or aerobics program, or both, during the latter half of pregnancy would have a negative effect on the course and outcome of labor. The onset, course, and outcome of labor were independently monitored in 131 well-conditioned recreational athletes who had an uneventful first half of pregnancy. Daily exercise performance was quantitated before conception and throughout pregnancy. Comparisons were made between the 87 women who continued to exercise regularly at or above 50% of their preconceptional level throughout pregnancy and the 44 who discontinued their regular exercise regimen before the end of the first trimester. The incidence of preterm labor was similar in the two groups (9%). Labor began significantly earlier in the exercise group (277 +/- 6 vs 282 +/- 6 days). The women who continued to exercise had a lower incidence of abdominal (6% vs 30%) and vaginal (6% vs 20%) operative delivery, and active labor was shorter (264 +/- 149 vs 382 +/- 275 min) in those who were delivered vaginally. Finally, clinical evidence of acute fetal stress (meconium, fetal heart pattern, and Apgar score) was less frequent in the exercise group (50% vs 26%), although birth weight was reduced (3369 +/- 318 vs 3776 +/- 401 gm). These data negate the initial hypothesis and indicate that, in well-conditioned women who regularly perform aerobics or run, continuation of these exercise regimens has a beneficial effect on the course and outcome of labor.
Adult↗
The lack of significant change in plasma progesterone and estradiol-17 beta levels before the onset of human labor.
Maternal plasma levels of progesterone and estradiol-17 beta were measured weekly by radioimmunoassay in 15 healthy women during the last trimester of normal pregnancy. There was a large individual variation for both hormones. The mean concentrations rose slightly with advancing gestational age but the ratio of progesterone to estradiol did not change. It is apparent that the onset of spontaneous labor cannot be predicted by measuring the levels of progesterone and estradiol-17 beta in maternal peripheral plasma.
Adolescent↗
Diurnal rhythms of labor and delivery in women: modulation by parity and seasons.
OBJECTIVES: Our purpose was to evaluate in women the diurnal (24 hour) rhythms of the onset of labor and time of delivery and their modulation by parity and seasons. STUDY DESIGN: A retrospective analysis was performed on 15,910 at term deliveries of single fetuses with noninduced labor. RESULTS: A diurnal rhythm of labor onset, with peak frequency at 8 PM and 9 AM was observed in nulliparous women but not in multiparous women. No diurnal rhythm of labor length was detectable. A diurnal rhythm of delivery, with peak values at 2 PM was evident in nulliparous but not in multiparous women. In nulliparous women the two acrophases of the diurnal rhythm of labor onset were closer in summer (10 hours) than in winter (13 hours). The acrophase of the diurnal rhythm of delivery progressively shifted to earlier hours from winter (5 PM) to summer (1 PM). CONCLUSIONS: These data show the attenuation of the diurnal rhythms of labor and delivery in multiparous women and their modulation by seasons.
Circadian Rhythm↗
[The physiological importance of prostaglandins in the mechanism of human labor].
Recent results indicate that prostaglandins play a major role in the mechanism of human labor. There are, however, no systematic studies on the role of prostaglandins in various forms of induction of labor. In the present study the concentration of 13,14-dihydro,15-ketoprostaglandin F2 (PGFM) in the maternal peripheral plasma was determined in labor of spontaneous onset, in labor after induction with oxytocin and in labor after induction by artificial rupture of membranes (ARM). In an additional group of women PGFM was determined before and immediately after delivery to get an insight into the mechanism of placental separation. In labor of spontaneous onset PGFM concentration increased significantly. In labour induced by oxytocin PGFM levels rose only in those women in whom induction of labor was successful. In induction of labor by ARM, PGFM level also increased in all women in whom induction was successful. At the time of placental separation PGFM concentration in the maternal blood increased dramatically. From the result of this study it is concluded that the increase of prostaglandin F synthesis is a necessary prerequisite for vaginal delivery and that prostaglandins are of major importance in the mechanism of placental separation and expulsion.
Dinoprost↗
Prostaglandin-endoperoxide H synthase-2 expression and activity increases with term labor in human chorion.
We investigated the changes in prostaglandin-endoperoxide H synthase (PGHS) specific activity and the levels and distribution of PGHS-1 and PGHS-2 mRNA in chorion collected at term before the onset of labor (CS) and after term labor and delivery (SL). PGHS specific activity and PGHS-2 mRNA abundance were higher in chorion collected after SL compared with that obtained at CS (P < 0.001); there was no difference in the levels of PGHS-1 mRNA between CS and SI, tissues. The increase in PGHS specific activity at SL was significantly correlated with PGHS-2 mRNA expression (P < 0.05) but not with PGHS-1 mRNA levels. In situ hybridization indicated that the pervasiveness of staining for PGHS-1 mRNA throughout full-thickness membranes did not change with labor onset; however, a greater number of cells expressed PGHS-2 in SL tissues. Our results demonstrate a selective increase in PGHS-2 expression and activity in chorion trophoblasts and mesenchymal cells with term labor onset. These observations are similar to those concerning amnion and imply that a concerted mechanism may exist in the fetal membranes to induce PGHS-2 expression at labor.
Chorion↗
Active management of prolonged pregnancy.
OBJECTIVES: We assessed perinatal morbidity and mortality of prolonged pregnancies (> or = 294 days) compared with those of term gestations. We also evaluated the impact of induction of labor compared with spontaneous onset of labor. STUDY DESIGN: This observational study included consecutive cases treated at Chicago Lying-In Hospital from July 1980 to December 1984. Complications, presence of meconium, indications for cesarean section, mode of delivery, perinatal morbidity (and mortality), meconium aspiration, and duration of labor were compared with those in the total hospital population, in infants weighing > or = 2500 gm, and within prolonged gestation groups; spontaneous onset and induced ("active management") labors were also compared. The chi 2 analysis was used. RESULTS: Of 12,930 deliveries there were 707 prolonged gestations (5.5%) and 10,698 with infants > or = 2500 gm. Among the prolonged gestations 67% were in multiparous women and 33% in primiparous women. Labor started spontaneously in 62%, and 38% underwent induction; the overall cesarean section rate was 17% with similar indications in both spontaneous onset and induction groups. Meconium was present in 34%; it was present in 23% of inductions, which is fewer (p < 0.01) than among those with spontaneous onset of labor (40%). Also there were fewer depressed neonates at 5 minutes (p = 0.03) among inductions. Meconium aspiration was seen in 24, with nine deaths. The perinatal mortality was 14 per 1000 (corrected 12.7/1000), significantly more than in the general population. Among those with spontaneous onset of labor it was 20.5 per 1000; there were no deaths among inductions. Postpartum maternal morbidity was 16% among cesarean sections and 4% among vaginal deliveries. CONCLUSIONS: Prolonged gestation has a high perinatal morbidity and mortality rate. All perinatal deaths were observed among patients whose labor started spontaneously. "Active management" (induction at 42 weeks) did increase the primary cesarean section rate compared with that of the general obstetric population; it did not do so among prolonged gestations and prevented perinatal deaths in this group. From this experience an active approach seems justified.
Cesarean Section↗
[Changes in 13,14-dihydro-15-keto-prostaglandin F2 alpha and dehydroepiandrosterone-sulfate (DHA-S) levels in amniotic fluid and maternal peripheral venous blood in late pregnancy and during labor].
To study the role of prostaglandin (PG) and steroids on the mechanism of parturition, levels of 13,14-dihydro-15-keto-prostaglandin F2 alpha (dhk.PGF2 alpha) and dehydroepiandrosterone-sulfate (DHA-S) in amniotic fluid and plasma during late pregnancy, labor, and puerperium, were measured by radioimmunoassay and gas chromatography-mass spectrometry. Seven patients at term were selected for this study and labor was induced by amniotomy. Amniotic fluid and maternal peripheral blood were obtained simultaneously from each individual at A) the artificial rupture of the membranes before the onset of labor, B) the onset of labor, C) the second stage of labor, D) the delivery, and E) 2 hours postpartum. No increase in either amniotic fluid or plasma dhk-PGF2 alpha was noticed when compared before and at the onset labor. However, there was a steady increase during labor and the maximum was reached at delivery. The dhk-PGF2 alpha concentration in amniotic fluid correlated well with that in maternal plasma. A similar pattern was observed in the DHA-S levels both in amniotic fluid and plasma. No apparent change was observed before the onset of labor, but there was a tendency to increase during labor. A significant correlation between the levels of dhk.PGF2 alpha and DHA-S in amniotic fluid was noticed. From the results obtained above, it is suggested that PG and DHA-S may be involved not in the initiation of labor but in the promotion of parturition. The biological significance of DHA-S on PG levels remains to be clarified.
Amniotic Fluid↗
Prostaglandin endoperoxide-H synthase (PGHS) activity and immunoreactive PGHS-1 and PGHS-2 levels in human amnion throughout gestation, at term, and during labor.
Prostaglandins (PGs) are of primary importance in the initiation and maintenance of labor in women. A major intrauterine source of prostaglandins is the amnion, which synthesizes increased amounts of PGE2 at term labor. Because PG endoperoxide-H synthase (PGHS) catalyzes the rate-limiting step of PG synthesis from arachidonic acid, we investigated the changes in amniotic PGHS specific activity during gestation and at term and preterm labor. Also, we determined the level of immunoreactive PGHS protein in the amnion to evaluate the mechanisms by which PGHS activity may be regulated. PGHS specific activity, measured at the amount of PGE2 produced by amnion microsomes under optimal conditions, was 18.2 +/- 3.7 pg PGE2/micrograms protein.min (mean +/- SE; n = 19) at term (37-42 weeks gestation) before the spontaneous onset of labor. PGHS specific activity was significantly higher after spontaneous term labor (38.9 +/- 6.0 pg PGE2/micrograms protein.min; n = 19; P < 0.05). Amnion samples from preterm (< 36 weeks gestation) nonlaboring patients contained low levels of PGHS specific activity (5.9 +/- 1.8 pg PGE2/micrograms protein.min; n = 9), which increased significantly with spontaneous preterm labor (28.3 +/- 6.8 pg PGE2/micrograms protein.min; n = 10; P < 0.05). Longitudinal analysis of the data showed that PGHS specific activity was low in the first and second trimesters of gestation, but increased dramatically before labor onset at term. We detected PGHS protein in all microsomal samples, with an antiovine PGHS antibody recognizing both PGHS-1 and -2 isoforms of the enzyme. However, there was no correlation between PGHS specific activity and the amount of immunoreactive PGHS protein. Using an antibody specific for PGHS-2, we detected immunoreactive protein in only 9 of the 25 tissues examined and found no correlation between PGHS specific activity and the amount of PGHS-2 protein. These results suggest that 1) PGHS specific activity in the amnion increases sharply before the onset of labor at term; 2) further increases in specific activity occur during term and preterm labor; and 3) the specific activity of PGHS in the amnion is not related directly to the amount of immunoreactive enzyme protein.
Amnion↗