Prostaglandin-Endoperoxide Synthase 1 Mediates the Timing of Parturition in Mice Despite Unhindered Uterine Contractility.

Cyclooxygenase (COX)-derived prostaglandins stimulate uterine contractions and prepare the cervix for parturition. Prior reports suggest Cox-1 knockout (KO) mice exhibit delayed parturition due to impaired luteolysis, yet the mechanism for late-onset delivery remains unclear. Here, we examined key factors for normal onset of parturition to determine whether any could account for the delayed parturition phenotype. Pregnant Cox-1KO mice did not display altered timing of embryo implantation or postimplantation growth. Although messenger RNAs of contraction-associated proteins (CAPs) were differentially expressed between Cox-1KO and wild-type (WT) myometrium, there were no differences in CAP agonist-induced intracellular calcium release, spontaneous or oxytocin (OT)-induced ex vivo uterine contractility, or in vivo uterine contractile pressure. Delayed parturition in Cox-1KO mice persisted despite exogenous OT treatment. Progesterone (P4) withdrawal, by ovariectomy or administration of the P4-antagonist RU486, diminished the delayed parturition phenotype of Cox-1KO mice. Because antepartum P4 levels do not decline in Cox-1KO females, P4-treated WT mice were examined for the effect of this hormone on in vivo uterine contractility and ex vivo cervical dilation. P4-treated WT mice had delayed parturition but normal uterine contractility. Cervical distensibility was decreased in Cox-1KO mice on the day of expected delivery and reduced in WT mice with long-term P4 treatment. Collectively, these findings show that delayed parturition in Cox-1KO mice is the result of impaired luteolysis and cervical dilation, despite the presence of strong uterine contractions.

Prolonged pregnancy in women is associated with attenuated myometrial expression of progesterone receptor co-regulator Krüppel-like Factor 9.

CONTEXT: Late-term pregnancy may lead to maternal and neonatal morbidity and mortality. Mice null for the progesterone receptor co-regulator Krüppel-like Factor 9 (KLF9) exhibit delayed parturition and increased incidence of neonatal deaths. OBJECTIVE: Our aim is to evaluate the contribution of myometrial KLF9 to human parturition. DESIGN: Myometrial biopsies were obtained from women with term (>37 to ≤41 wk) and late-term (>41 wk) pregnancies during cesarean delivery and assessed for gene and protein expression. Human myometrial cells transfected with nontargeting or KLF9 small interfering RNAs (siRNA) were treated with the progesterone antagonist RU486 and analyzed for pro-inflammatory chemokine/cytokine gene expression. SETTING: The study took place in a University-affiliated tertiary care hospital and University research laboratory. PATIENTS: Term patients (n = 8) were in spontaneous active labor whereas late-term patients (n = 5) were either in or were induced to active labor, prior to elective cesarean delivery. OUTCOME MEASURES: Steroid hormone receptor, contractility, and inflammation-associated gene expression in myometrial biopsies and in siKLF9-transfected, RU486-treated human myometrial cells was associated with KLF9 expression levels. RESULTS: Myometrium from women with late-term pregnancy showed lower KLF9, total PGR, and PGR-A/PGR-B isoform expression. Transcript levels of select chemokines/cytokines were up- (CSF3, IL1, IL12A, TGFB2) and down- (CCL3, CCL5, CXCL1, CXCL5, IL15) regulated in late-term relative to term myometrium. Knock-down of KLF9 expression in RU486-treated human myometrial cells modified the expression of PGR and labor-associated cytokines, relative to control siRNA-treated cells. CONCLUSIONS: Myometrial KLF9 may contribute to the onset of human parturition through its regulation of PGR expression and inflammatory signaling networks.

The expression of prostaglandin receptors EP3 and EP4 in human cervix in post-term pregnancy differs between failed and successful labor induction.

OBJECTIVE: To investigate expression and localization of prostaglandin receptors EP1-4 and FP and localization of stromal factors CTGF (connective tissue growth factor), furin, calgranulin B and ALOX15 (arachidonate 15-lipooxygenase) in human cervical tissue from post-term women with failed or successful labor induction after prostaglandin priming. DESIGN: Experimental prospective clinical study. SETTING: Tertiary obstetric care center. POPULATION: Twenty-six women giving birth post-term, with failed or successful labor induction, and a control group consisting of 19 women with spontaneous onset of labor and delivery at term. METHODS: Biopsies were obtained from post-term women with successful (responders; R) and failed (non-responders; NR) labor induction. Women with spontaneous delivery at term were included as controls (C). mRNA expression was determined with real time PCR, protein expression and localization with immunohistochemistry. MAIN OUTCOME MEASURES: Comparisons of mRNA and protein expressions between post-term pregnancies with failed and successful labor induction as well as term controls. RESULTS: EP4 mRNA expression was down-regulated concomitant with an up-regulation of EP3 mRNA expression in cervix from the NR group as compared with the R group. In stroma, immunoreactivity of the EP4 protein was increased in the NR group as compared with R and C groups. CONCLUSIONS: Failure of cervical ripening, after local application of prostaglandins for labor induction, may be caused by the increased expression of EP3 and concomitant decrease in EP4 expression.

Postdate pregnancy: changes of placental/membranes 11ß-hydroxysteroid dehydrogenase mRNA and activity.

11ß-Hydroxysteroid dehydrogenase 1 and 2 (11ß-HSD1 and 11ß-HSD2) are involved in the complex mechanism of human parturition. The present study examined mRNA expression and activity of membrane 11ß-HSD1 and placental 11ß-HSD2 in postdate pregnancies according to response of labor induction. In comparison to postdate women who had spontaneous delivery or after induction the non-responders showed significantly low c and high 11ß-HSD2 expression and activity These data suggest that disrupted expression and activity of 11ß-HSDs may occur in some postdate pregnancies.

Poor spontaneous and oxytocin-stimulated contractility in human myometrium from postdates pregnancies.

Prolongation of pregnancy i.e. going more than 10 days over the estimated due date, complicates up to 10% of all pregnancies and is associated with increased risk to both mother and fetus. Despite the obvious need for contractions of the uterus to end pregnancy, there have been no studies directly examining the role of uterine smooth muscle, myometrium, in the aetiology of prolonged pregnancy. This study tested the hypothesis that the intrinsic contractile characteristics of myometrium taken from women with prolonged pregnancy (>41 weeks and 3 days) was reduced compared to those delivering at term (39-41 weeks). We recruited women undergoing Caesarean Section (CS) delivery either pre-labour (n = 27) or in labour (n = 66) at term or postdates. The contractile ability of the postdates myometrium, whether spontaneous or elicited by oxytocin or high-K solution, was significantly reduced compared to term myometrium. These differences remained when adjusted for parity and other maternal characteristics. The findings remained significant when expressed per cross sectional area. Histological examination revealed no differences between the two groups. The contractile differences were however related to intracellular Ca transients suggesting an effect of [Ca] on reduced force production in the postdates group. In summary, myometrium from prolonged pregnancies contracts poorly in vitro even when stimulated with oxytocin and in active labour. Responses to high K(+) and measurements of Ca suggest that alterations in excitation contraction coupling, rather than any histological changes of the myometrium, may underlie the differences between term and postdates myometrium. We show that postdates pregnancy is associated with poor myometrial activity and suggest that this may contribute to increased myometrial quiescence and hence, prolonged gestation.

Correlation with placental kisspeptin in postterm pregnancy and apoptosis.

Postterm pregnancy represents a condition associated with trophoblast apoptosis. Kisspeptin is a peptide able to induce apoptosis by a specific receptor, GPR54, through the upregulation of proapoptotic genes. The aims of the study were to evaluate (1) the messenger RNA (mRNA) expression of kisspeptin, GPR54, Bax/Bcl2, and p21 in postterm placentas and (2) kisspeptin ability to act on apoptosis in the third trimester placental explants. Placental specimens were collected from spontaneous term and postterm delivery and kisspeptin, GPR54, Bax/Bcl2, and p21 mRNA expression levels were analyzed by real-time polymerase chain reaction. Placental explants, collected from elective term cesarean sections, treated with different doses of kisspeptin were analyzed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL). The expression levels of all the genes studied in postterm placentas were significantly higher than in-term placentas. Kisspeptin-induced apoptosis in placental explants with a dose-dependent effect, and TUNEL assay demonstrated the kisspeptin involvement in the apoptotic placental processes. Our present findings led us to hypothesize that kisspeptin may represent a placental proapoptotic agent acting in physiological and/or pathological pregnancy conditions in which placental apoptosis mechanisms are increased.

Associations of prenatal metabolic abnormalities with insulin and adiponectin concentrations in human milk.

BACKGROUND: Emerging evidence indicates that metabolic hormones are present in human milk, but, to our knowledge, no studies have investigated the impact of maternal metabolic status assessed during pregnancy on insulin and adiponectin concentrations in milk. OBJECTIVES: We aimed to investigate the associations of prenatal metabolic abnormalities with insulin and adiponectin in human milk and to compare the concentrations of these hormones in early and mature milk. DESIGN: Pregnant women aged ≥20 y with intention to breastfeed and without preexisting type 1 or 2 diabetes were recruited. Participants (n = 170) underwent a 3-h oral-glucose-tolerance test at 30 wk (95% CI: 25, 33 wk) gestation and donated early (the first week postpartum) and mature (3 mo postpartum) milk. RESULTS: Adiponectin and insulin concentrations in early milk were higher than those in mature milk (both P < 0.0001). Prenatal metabolic abnormalities, including higher pregravid BMI (ß ± SEE: 0.053 ± 0.014; P = 0.0003) and gravid hyperglycemia (0.218 ± 0.087; P = 0.01), insulin resistance (0.255 ± 0.047; P < 0.0001), lower insulin sensitivity (-0.521 ± 0.108; P < 0.0001), and higher serum adiponectin (0.116 ± 0.029; P < 0.0001), were associated with higher insulin in mature milk after covariate adjustment. Prenatal metabolic measures were not associated with milk adiponectin, but obstetrical measures that included nulliparity (0.171 ± 0.058; P = 0.004), longer duration of gestation (0.546 ± 0.146; P = 0.0002), and unscheduled cesarean delivery (0.387 ± 0.162; P = 0.02) were associated with higher adiponectin in early milk after covariate adjustment, including the time elapsed from delivery to milk collection. CONCLUSION: Maternal prenatal metabolic abnormalities are associated with high insulin concentrations in mature milk, whereas only obstetrical variables are associated with adiponectin concentrations in early milk.

Cervical insulin-like growth factor binding protein-1 (IGFBP-1) to predict spontaneous onset of labor and induction to delivery interval in post-term pregnancy.

OBJECTIVE: To evaluate whether insulin-like growth factor binding protein-1 (IGFBP-1) assessed in cervical secretion can predict successful induction and spontaneous onset of labor in post-term pregnancy, compared to ultrasound measurement of cervical length and Bishop score. DESIGN: Cohort study, originating from a randomized controlled trial. SETTING: Obstetric department of a university and tertiary referral hospital, Norway. POPULATION: Five hundred and eight post-term women who had been randomized to induction of labor or expectant management 1 week beyond estimated day of delivery (289 [±2] days of gestation). METHODS: Time to delivery was related to presence of IGFBP-1 in cervical secretion, Bishop score and ultrasound measurement of cervical length recorded at inclusion. MAIN OUTCOME MEASURES: Spontaneous onset of labor and delivery within 3 days in the expectant management, and delivery within 24 hours of induction in the induction group. Test characteristics (sensitivity, specificity and negative and positive values and likelihood ratios) for IGFBP-1, Bishop score and cervical length were calculated. Logistic regression and Cox regression were used to account for parity and body mass index. RESULTS: With expectant management, IGFBP-1 predicted spontaneous labor onset and delivery within 72 hours with low sensitivity and high specificity (0.45 and 0.80, respectively), as did Bishop score (0.24, 0.92). Cervical length was more sensitive (0.67, 0.58). IGFBP-1 predicted successful induction within 24 hours with low sensitivity and high specificity (0.30, 0.85), such as Bishop score (0.06, 1.00) and cervical length (0.45, 0.76). Parity enhanced successful induction. CONCLUSION: IGFBP-1 predicts both spontaneous labor onset and successful induction in post-term pregnancy. Bishop score and cervical length performed equally well.

Alterations in saliva steroid hormone levels after oral mifepristone administration in women with pregnancies of greater than 41 weeks' gestation.

The objective of this study is to describe the effects of oral mifepristone administration on saliva levels of estradiol, estriol, progesterone, and cortisol in women with postdates pregnancy. As an adjunct to a randomized controlled trial comparing 200 mg oral mifepristone to placebo for cervical ripening and labor induction in women with pregnancies greater than 41 weeks' gestation, saliva samples were obtained before drug administration and every 6 hours thereafter for 24 hours. Estradiol, estriol, progesterone, and cortisol levels were measured by radioimmunoassay. Ninety-seven participants received mifepristone, and 83 received placebo. Saliva steroid hormone data were available for 71 mifepristone-and 60 placebo-treated women. Mean baseline saliva estradiol, estriol, progesterone, and cortisol levels were similar between study groups. At 24 hours after study medication administration, saliva estradiol, estriol, progesterone, and cortisol levels in the mifepristone group were significantly elevated compared with baseline. There was no significant change in hormone levels in the placebo group. Oral mifepristone significantly increased saliva estradiol, estriol, progesterone, and cortisol compared with placebo. This may reflect mifepristone's antiglucocorticoid properties. These hormone elevations may contribute to the mechanism by which mifepristone causes cervical ripening and increases myometrial activity.

Effects of progesterone on iNOS, COX-2, and collagen expression in the cervix.

This study examines the relationship between inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in the control of cervical ripening and parturition under normal (normal term pregnancy) and abnormal (preterm labor and prolongation of pregnancy) conditions by (a) measuring changes in the collagen both visually and quantitatively, (b) localizing and characterizing iNOS and COX-2 under normal conditions, and (c) characterizing the changes in iNOS and COX-2 under abnormal conditions. Cervices are obtained from estrus and timed pregnant Sprague-Dawley rats (n=4-10 per group). Preterm labor is induced with Onapristone (3 mg/rat; progesterone antagonist) and the prolongation of pregnancy with progesterone (2.5 mg, twice daily). Collagen changes are measured and visualized with the picrosirius polarization method. RT-PCR is used to characterize the mRNA expression (p<0.05), and immunohistochemistry is used to localize the protein expression for iNOS and COX-2. The organization and birefringence of the collagen during pregnancy decreased and is supported by changes in the luminosity (p<0.001). The iNOS and COX-2 enzymes were localized in cervical smooth muscle, vascular smooth muscle, and epithelium. Under normal conditions, iNOS mRNA levels decreased as COX-2 mRNA levels increased demonstrating an inverse correlation (Spearman r = -0.497; p=0.00295). Onapristone stimulated preterm labor, increasing the iNOS and COX-2 mRNA (p<0.05). The increase demonstrated a positive correlation (Spearman r = 0.456; p=0.03). Progesterone prolonged pregnancy, decreasing the iNOS and COX-2 mRNA (p=0.036). In conclusion, there may be an interaction between the nitric oxide and prostaglandin pathways in cervical ripening and parturition.

Alterations of N-glycan branching and expression of sialic acid on amniotic fluid alpha-1-acid glycoprotein derived from second and third trimesters of normal and prolonged pregnancies.

BACKGROUND: Alterations in the AGP glycoform pattern are not only disease related, but also can occur during physiological processes such as pregnancy. In this paper, possible changes in human amniotic fluid AGP glycan branching and in the type of sialic acid glycosidic attachment to glycans were analyzed with regard to different stages of human pregnancy. METHODS: Crossed-affinity immunoelectrophoresis with concanavalin A was used to study AGP branching and lectin-ELISA with two agglutinins from Maackia amurensis and Sambucus nigra was applied to differentiate alpha2,3 and alpha2,6 type sialic acid attachments. RESULTS: Despite almost unchanged levels of total amniotic fluid AGP during pregnancy, alterations in N-glycan branching and in the expression of sialic acid linkage on AGP were found to be associated with different stages of normal pregnancy. Amniotic fluid AGP glycans derived from third trimester compared with those from the second trimester had a higher percentage of tri- and tetra-antennary sialylated N-glycans. In the second trimester, sialic acid alpha2,6 linkage occurred twice as frequently as alpha2,3 linkage, while during the third trimester alpha2,3 linkage increased and both types of linkage appeared in equal proportion. CONCLUSIONS: Branched and alpha2,3-sialylated AGP glycoforms in amniotic fluid could contribute to natural innate fetomaternal defense.

Cervical nitric oxide release in women postterm.

OBJECTIVE: Nitric oxide may be a factor in cervical ripening. We compared the nitric oxide metabolite levels in cervical fluid in women going beyond term and in women delivering spontaneously at term. METHODS: We studied a total of 208 women with singleton pregnancies: 108 women who went beyond term (294 days or longer), and 100 women who went spontaneously into labor at term. Cervical fluid samples, collected well before the initiation of labor, were assessed for nitric oxide metabolites using an assay with a detection limit of 3.8 micromol/L. RESULTS: Women going beyond term had detectable levels of nitric oxide metabolites in their cervical fluid (60%) less often (P =.001) than women delivering at term (87%). The nitric oxide metabolite concentration in cervical fluid in women going beyond term (median 23.5 micromol/L; 95% confidence interval less than 3.8, 31.8) was 4.5 times lower (P <.001) than that in women delivering at term (median 106.0 micromol/L; 95% confidence interval 81.8, 135.0). Such a difference (14.0 versus 106.0 micromol/L) also existed when only the 66 women going into spontaneous postterm labor were included in the comparison. Both nulliparous (median less than 3.8 micromol/L) and parous (median 31.3 micromol/L) women going beyond term had lower (P <.01) cervical fluid nitric oxide metabolite levels than nulliparous and parous women delivering at term (medians 76.1 and 101.3 micromol/L, respectively). In the postterm group, women with cervical fluid nitric oxide metabolite concentrations at or below the median failed more often (P <.001) to progress in labor and had longer (P =.02) duration of labor than those with cervical fluid nitric oxide metabolite concentrations above the median. CONCLUSION: Reduced cervical nitric oxide release may contribute to prolonged pregnancy. LEVEL OF EVIDENCE: II-2

Isoenzymes of N-acetyl-beta-hexosaminidase in complicated pregnancy.

The activity of N-acetyl-beta-hexosaminidase was found to be significantly higher in the placentas collected after delivery from women in puerperium with symptoms of prolonged pregnancy or complicated by EPH gestosis, than in placentas from normal pregnancy. Isoelectrofocusing of placenta homogenates showed the presence of isoenzymes A, P and B of N-acetyl-beta-hexosaminidase. Different isoenzyme A patterns in homogenates were observed in placentas obtained from normal and prolonged pregnancies and in those complicated by EPH gestosis.

Fetal fibronectin in vaginal fluid of women in prolonged pregnancy.

The aim of this study was to determine fetal fibronectin in vaginal fluid of women in prolonged pregnancy, its relationship to a modified Bishop score and its predictiveness of delivery within 3 days. Vaginal samples were collected from 80 women at 42 weeks of gestation for the fetal fibronectin assay. A modified Bishop score was estimated. Fetal fibronectin was determined by a quantitative enzyme immunoassay. The concentration of fetal fibronectin in vaginal fluid was elevated in only 36 of the 80 women. The Bishop score and the time between sampling and delivery were not associated with an elevated fetal fibronectin (> or = 0.05 mg/l). We conclude that fetal fibronectin is not a good indicator of delivery within 3 days. The findings add to our understanding of the complexity of the etiology of postterm labor.

[The studies of the estrogen and progesterone receptor levels in the placenta, fetal membrane, uteroplacental bed and myometrium in patients with prolonged pregnancy].

OBJECTIVE: To reveal the relation between the changes of the estrogen receptor (ER) and progesterone receptor (PR) levels in the target tissues and the duration of pregnancy. METHODS: The method combining fluorescence with hormones and polyspectrum-data system were used to qualitatively and quantitatively assay the estrogen and progesterone receptor concentrations in the placenta, fetal membrane, uteroplacental bed and uterine myometrium in 30 cases with prolonged pregnancy and 27 cases of term pregnancy. RESULTS: ER concentrations in the uteroplacental bed and fetal membrane of the prolonged pregnancy group were markedly lower than that in the term group; ER/PR values in every target tissues of the prolonged pregnancy were much less than that in the term group. There is a positive relationship between ER and PR levels in all target tissues evidently; and ER/PR value in the lower segment of the uterine myometrium in the group with uterine contraction were significantly higher than that of group without uterine contraction. CONCLUSIONS: The mechanisms of both prolonged pregnancy and onset of labour were revealed partly in this study. The cause of prolonged pregnancy is relatively concerned with the decline of ER levels and the ascent of the PR concentrations in the target tissues. Also the uterine contraction is induced by the increase of ER and decrease of PR.

[Fetal metabolism in post term pregnancy based on biochemical investigations of amniotic fluid. IV. Ion composition]. / Metabolizm plodu w ciazy przeterminowanej--na podstawie badan biochemicznych plynu owodniowego. IV. Sklad jonowy.

Concentrations of calcium, sodium, magnesium, calcium (total and ionised) and inorganic phosphorus were determined in amniotic fluid. Samples were taken from patients between 42-43 week of gestation (investigated group) and between 38 and 40 week (control group). Micro-methods, generally acknowledged in laboratories of clinical biochemistry were used. In the protracted pregnancies increase of magnesium levels and decrease of sodium levels were observed. No differences in concentrations of calcium, calcium (total and ionised) and inorganic phosphorus between investigated and control group were noted. Independently of the duration of pregnancy, near term or post term, ionised calcium constituted 90% of total calcium in amniotic fluid.

[Fetal metabolism in post-term pregnancy based on biochemical examinations of amniotic fluid. V. Glucose, bilirubin, H+ ions, hormones and tests of lung maturation]. / Metabolizm plodu w ciazy przeterminowanej--na podstawie badan biochemicznych plynu owodniowego. V. Glukoza, bilirubina, jony H+, hormony i testy dojrzalosci pluc.

Concentrations of glucose, bilirubin, H+ ions, estriol, HPL were determined in the samples of amniotic fluid from post term and near term pregnancies. Investigated group consisted of samples taken between 42-43 week of gestation, control group between 38-40 week. In both groups biochemical tests of pulmonary maturation--Lectin/Sphingomyelin ratio, foam test, 650 nm absorbance were carried out. In the diagnosis of post term pregnancy glucose concentrations, oestrogens, HPL, 650 nm adsorption, foam test and L/S ratio had proper diagnostic value. No differences were observed in bilirubin concentrations.

Maternal, fetal and amniotic fluid prolactin levels in term and post-term pregnancies.

Prolactin (PRL) levels in maternal serum, amniotic fluid and mixed cord blood from 11 women with post-term pregnancies and 64 women with normal term pregnancies were measured by immunoenzymetric assay in order to investigate their possible role in the onset of labor. No differences were found between term and post-term pregnancies, and it is concluded that PRL probably has no function in triggering labor.