Fetal signals and parturition

Challis, John; Bloomfield, Frank H.; Bocking, Alan D.; Casciani, Valentina; Chisaka, Hiroshi; Connor, Kristin L.; Dong, Xuesen; Gluckman, Peter D.; Harding, Jane E.; Johnstone, Jim; Li, Wei; Lye, Stephen J.; Okamura, Koji; Premyslova, Marina

doi:10.1111/j.1447-0756.2005.00342.x

Cited by 74 publications

(42 citation statements)

References 31 publications

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“…Prostaglandins (PGs) have been considered to play a central role in the mechanisms responsible for parturition in humans and animals and oviposition in birds [1][2][3][4][5][6]. The evidence in favor of PGs in the onset of labor includes the fact that their amniotic fluid (AF) concentration increases with labor.…”

Section: Introductionmentioning

confidence: 99%

Amniotic fluid prostaglandin concentrations increase before the onset of spontaneous labor at term

Lee

Romero

Park

et al. 2008

The Journal of Maternal-Fetal & Neonatal Medicine

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Objectives. The role of prostaglandins (PGs) in the onset of human parturition has been controversial. Specifically, some investigators have proposed that PGs are the consequence rather than the cause of labor. An important question is whether or not amniotic fluid (AF) PG concentrations increase before the onset of labor in humans. Methods. The concentrations of PGs were determined in AF obtained from 167 singleton pregnant women with intact membranes. Patients were divided into four groups: (1) preterm not in labor (gestational age 15-36 weeks, n ¼ 65); (2) term not in labor (n ¼ 68); (3) spontaneous labor at term with cervical dilatation 54 cm (n ¼ 25); (4) spontaneous labor at term with cervical dilatation 4 cm (n ¼ 9). AF was obtained by transabdominal amniocentesis or collected at the time of cesarean delivery. All patients met the following criteria: (1) normal pregnancy outcome; (2) clear AF; (3) no significant medical or obstetric complications such as diabetes mellitus, preeclampsia, preterm birth, fetal growth restriction, or major congenital malformations; and (4) no significant neonatal complications. The concentrations of PGE2 and PGF2a in AF were determined by enzyme-linked immunosorbent assay (ELISA). Non-parametric analysis was performed. Results. (1) AF PG concentrations remained unchanged with advancing gestation until 36 weeks of gestation; (2) however, an abrupt increase in AF PG concentrations was observed before the onset of labor at term; (3) among cases without labor at term, the median AF PGF2a concentration increased with advancing gestation; (4) the presence of labor and the degree of cervical dilatation were significantly associated with a higher concentration of PGF2a.Conclusions. An abrupt increase in AF PG concentrations (25-fold for PGF2a) occurs before the onset of spontaneous labor at term in humans; these observations suggest that PGs increase prior to the onset of labor and contradict the claim that an increase in PG concentrations is the consequence of labor.

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Section: Introductionmentioning

confidence: 99%

Amniotic fluid prostaglandin concentrations increase before the onset of spontaneous labor at term

Lee

Romero

Park

et al. 2008

The Journal of Maternal-Fetal & Neonatal Medicine

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“…Birth is thought to be triggered by a decrease in systemic progesterone concentrations (withdrawal) (3), even though this is not evident in mares (4), women, or guinea pigs (5), a disparity that limits the utility of other animal models for preterm labor (6). The vast majority of studies have focused on measuring progesterone, with most using immunoassays that necessarily cross-react with multiple pregnanes (7), the bioactivity of which remain uncharacterized.…”

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confidence: 99%

Pregnancy without progesterone in horses defines a second endogenous biopotent progesterone receptor agonist, 5α-dihydroprogesterone

Scholtz

Krishnan

Ball

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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One of the most widely accepted axioms of mammalian reproductive biology is that pregnancy requires the (sole) support of progesterone, acting in large measure through nuclear progesterone receptors (PRs) in uterine and cervical tissues, without which pregnancy cannot be established or maintained. However, mares lack detectable progesterone in the latter half of pregnancy. Instead of progesterone, several (mainly 5α-reduced) pregnanes are elevated and have long been speculated to provide progestational support in lieu of progesterone itself. To the authors' knowledge, evidence for the bioactivity of a second potent endogenously synthesized pregnane able to support pregnancy in the absence of progesterone has never before been reported. The 5α-reduced progesterone metabolite dihydroprogesterone (DHP) was shown in vivo to stimulate endometrial growth and progesterone-dependent gene expression in the horse at subphysiological concentrations and to maintain equine pregnancy in the absence of luteal progesterone in the third and fourth weeks postbreeding. Results of in vitro studies indicate that DHP is an equally potent and efficacious endogenous progestin in the horse but that the PR evolved with increased agonistic potency for DHP at the expense of potency toward progesterone based on comparisons with human PR responses. Sequence analysis and available literature indicate that the enzyme responsible for DHP synthesis, 5α-reductase type 1, also adapted primarily to metabolize progesterone and thereby to serve diverse roles in the physiology of pregnancy in mammals. Our confirmation that endogenously synthesized DHP is a biopotent progestin in the horse ends decades of speculation, explaining how equine pregnancies survive without measurable circulating progesterone in the last 4 to 5 mo of gestation.ince first crystallized almost eight decades ago, progesterone has remained the only endogenous member of the progestin class of steroids defined by its singular ability to maintain pregnancy (1), acting, in large measure, through nuclear progesterone receptors (PRs) in uterine and cervical tissues, without which pregnancy cannot be established or maintained (2). Birth is thought to be triggered by a decrease in systemic progesterone concentrations (withdrawal) (3), even though this is not evident in mares (4), women, or guinea pigs (5), a disparity that limits the utility of other animal models for preterm labor (6). The vast majority of studies have focused on measuring progesterone, with most using immunoassays that necessarily cross-react with multiple pregnanes (7), the bioactivity of which remain uncharacterized. This is reasonable because, in contrast to androgens, estrogens, and corticoids, for which multiple natural biopotent analogs are known, no other endogenous pregnane has ever been shown to substitute for progesterone in pregnancy in any mammal.However, over five decades ago, Short (8) reported that circulating progesterone concentrations in pregnant mares were surprisingly low at <4 ng/mL, as did Holtan e...

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“…It has been suggested that this increase of fetal adrenal gland, particularly its central zone may have an important role in the endocrine regulation of parturition. [6,[16][17][18]. Turan et al [6] considered reasonable to propose that a disproportionate increase in the size of the fetal adrenal gland would allow noninvasive recognition of premature activation of the delivery cascade.…”

Section: Discussionmentioning

confidence: 99%

Can fetal adrenal artery Doppler velocimetry predict delivery date in pregnant women with spontaneous preterm birth?

et al. 2017

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Aim: To assess the accuracy of delivery date predictions made using fetal adrenal artery Doppler velocimetry in pregnant women with spontaneous preterm birth (PB) and to compare these predictions with cervical length (CL) measurements.Material and methods: A prospective study was performed with 51 pregnant women whose gestational lengths were between 24 and 36 weeks. The main outcome was the time between the Doppler velocimetry examination and delivery, categorized as delivery within 7 days or 7 days later after the examination. A receiver operating characteristics curve was performed to define the cutoffs among deliveries within 7 days for fetal adrenal artery Doppler velocimetry parameters and CL measurements.Results: The incidence of delivery within 7 days was 37.3%, with a statistically significant difference for the pulsatility index (PI; p=0.045) and resistance index (RI; p=0.030) of the fetal adrenal artery. The best cutoff values of PI and RI for predicting deliveries within 7 days were 1.65 and 0.78, respectively. The sensitivity and specificity of PI, RI, and CL (20 mm) were 73.7% (95% CI: 51.9–95.5) and 56.3% (95% CI: 38.1–74.4); 68.4% (95% CI: 45.4–91.4) and 62.5% (95% CI: 44.8–80.2); and 76.5% (95% CI: 54.0–99.0) and 78.1% (95%: CI 71.1–97.7), respectively.Conclusion: Fetal adrenal artery Doppler velocimetry can predict delivery within 7 days among pregnant women in cases of spontaneous PB and this prediction is similar to the predictions made using CL measurements.

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Fetal signals and parturition

Cited by 74 publications

References 31 publications

Amniotic fluid prostaglandin concentrations increase before the onset of spontaneous labor at term

Amniotic fluid prostaglandin concentrations increase before the onset of spontaneous labor at term

Pregnancy without progesterone in horses defines a second endogenous biopotent progesterone receptor agonist, 5α-dihydroprogesterone

Can fetal adrenal artery Doppler velocimetry predict delivery date in pregnant women with spontaneous preterm birth?

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