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PubMed1977

Progesterone and oestrogen in pregnancy and parturition: comparative aspects and hierarchical control.

The different ways in which the progesterone requirements of pregnancy are met in various species are reviewed here. Progesterone production expressed in terms of metabolic body weight lies within about one order of magnitude in several species (but not in the rat), whether the hormone is predominantly ovarian or placental in origin. Parturition is usually preceded by a decrease in the plasma concentration of progesterone and the evidence which suggests that a decrease in secretion involves enzyme induction is summarized. In the sheep a sequence of well-marked hormonal changes can be discerned--an increase in fetal cortisol secretion followed by a fall in placental progesterone and a rise in oestrogen and prostaglandin F2alpha secretion. This sequence has been interpreted in terms of hierarchical control theory which envisages a series of levels placed in a descending order of importance and in which there is a downward transmission of a signal from a higher level that modifies activity at a lower level. A dominant level in the hierarchy in the sheep and pig seems to be the fetal hypothalamus and pituitary, but in the rabbit the maternal hypothalamus, pituitary and ovary play a more dominant role.

Adrenal Glands↗

PubMed1976

The structure of the human symphysis pubis with special consideration of parturition and its sequelae.

Review of the structure of the symphysis pubis, based on my extensive study of the pelvic joints ('31) shows changes from age, function, pregnancy hormones and stress of parturition. Primary physiologic shearing clefts and secondary traumatic clefts in cartilage are more frequent in females. Interdigitations in the young osteocartilaginous border secure the vulnerable growth cartilage against increasing shearing forces. The retropubic eminence, ligamentous or cartilaginous, forms earlier in females, later, due to bony lipping in males, secondary to extrusion of disc cartilage. Ovarian and placental hormones in pregnancy cause remodeling and resorption of the posterior margin of the pubic facette and adjacent cortex, making a (variably) deep bony groove for greatly hypertrophied transverse ligaments. Delivery of a mature infant produces traumatic changes leading to extrusion of torn fibrocartilage in any direction, progressively loosening the symphysis, producing cartilage nodules, cysts and reactive bone formation. Older age degenerative arthritis is more frequent in parous females.

Age Factors↗

PubMed1978

A re-examination of parturition scars on the human female pelvis.

Pits, cavities and depressions located on the dorsal surface of the pubic symphysis of females have been attributed to the trauma of parturition. Earlier research based on human skeletal remains provides inadequate information on the individual's obstetrical history. The 68 female pubic bones that were studied had comprehensive medical records indicating whether or not each female had given birth. Fourteen and one-half percent of the females who had not given birth exhibited trace to small scarring of the pubic symphysis and 23.4% of the females who had not given birth exhibited medium to large scarring. It is suggested that bony changes previously used as an indicator of child bearing must be re-examined in light of the fact that "birth scarring" has been found in women known not to have had children.

Female↗

PubMed1982

Skeletal tuberculosis, pelvic contraction, and parturition.

Obliquely contracted pelvis was observed in association with tuberculosis and dystocia (difficult parturition) in four out of 762 childbearing women in a Southeast Asian population. It is hypothesized that the pelvic contracture results from tuberculosis of the sacro-iliac joint with destruction of the sacral ala. This gross morphologic deformity, as observed in living populations, may be a useful marker for skeletal tuberculosis in prehistoric and historic populations as well. The occurrence of obliquely contracted pelvis with consequent dystocia as a specific complication of systemic tuberculosis may have direct implications for differential reproductivity.

Anthropology, Physical↗

PubMed1985

The influence of parturition on peripheral blood mononuclear phagocyte subpopulations in pregnant women.

Mononuclear phagocytes (MPs) from human peripheral blood were separated on discontinuous Percoll gradients into two subpopulations. A high density population was isolated which contained less mature MPs, while the MPs in the low density population were more mature cells. The proportion of high density MPs was found to increase sharply in conjunction with the peripheral blood monocytosis associated with parturition in women. The data show that there is a measurable response in the circulating MP pool to this acute inflammatory stimulus and that this response is manifested as an increase in absolute numbers of both total and high density MPs. No significant change was found in the number of low density MPs.

Cell Adhesion↗

PubMed1983

The causes of perinatal death induced by prenatal exposure of rats to the pesticide, mirex. Part I: Pre-parturition observations of the cardiovascular system.

Prenatal exposure to mirex, a chlorinated hydrocarbon insecticide, induces a high rate of perinatal death, but only a low incidence of visible abnormalities which could help to account for these deaths. This study is an attempt to determine the cause of these deaths. Pregnant rats were intubated with a moderate dose of mirex, in oil, 6 mg/kg/day, on days 8 1/2-15 1/2 of gestation. Observations, on 78 control and 136 treated fetuses, were made on the morning before parturition was expected. Fetuses were sequentially exposed and electrocardiograms obtained with the fetus attached to the placenta and uterus. ECGs were evaluated for rate of beat, regularity of beat, PR intervals, and other features. Fetuses were examined for edema level and vitality. None of the controls were dead and none had abnormal ECGs. Of the treated group, 14% were dead, 16% had a first-degree heart block, and 2% had a second-degree heart block. Some (6%) had slow, feeble atrial beats only, possibly a third-degree block, and appeared to be dying. The severity of the symptoms was proportional to the degree of visible edema. Most of the fetuses with little or no visible edema had normal ECGs, but the majority of the moderate to severely edematous fetuses (i.e., with a layer of subcutaneous edema across the back of 0.5 mm or more) had abnormal ECGs and/or were either dead or dying. These data show that the effects of mirex on the fetal cardiovascular system are a major factor in inducing prenatal death.

Abnormalities, Drug-Induced↗

PubMed1998

Female reproduction in mice lacking the prostaglandin F receptor. Roles of prostaglandin and oxytocin receptors in parturition.

Female mice lacking the receptor for prostaglandin F2 alpha (FP) do not deliver fetuses at term, although these can be successfully rescued by cesarean section. No induction of oxytocin receptor mRNA is found in the uterus of these mice, and they show no uterine contraction on intravenous administration of oxytocin. Furthermore, a decline in serum progesterone levels during the periparturition period is not observed in these animals. Ovariectomy at day 19 of pregnancy restored induction of the oxytocin receptor and caused successful delivery in these animals. These results indicate not only the essential role of luteolytic PGF 2 alpha action in natural parturition but also the importance of oxytocin receptor induction in this process.

Animals↗

PubMed1992

Immunohistochemical localization of the eosinophil major basic protein in the uterus horn and cervix of the rat at term and after parturition.

Distribution of the eosinophil major basic protein (MBP) was studied in the rat uterus horn and cervix by means of immunohistochemistry using an antiserum raised against rat MBP. Various hormonal contexts were investigated: pre- and post-parturition, the estrous cycle, and ovariectomy followed by hormonal treatment or without treatment. MBP was detectable in the cervix as early as 12 h post-partum, appearing in the stroma close to the myometrium. The MBP had spread throughout the stroma toward the luminal epithelium after a few days. In contrast, no MBP was seen in sections of the corresponding pre- and post-partum uteri and in the pre-partum cervix. In cycling rats, MBP was distributed equally in the cervix and uterus and was more abundant during proestrus and estrus. In ovariectomized rats subsequently treated with progesterone, no MBP was detected in the cervix or uterus. In the cervix of ovariectomized rats treated with estradiol, MBP first appeared in the muscle layer situated between the two cervical lumina and then reached the stroma; within a few days only the stroma was stained. Inversely, in the uterus MBP-staining first appeared in the stroma. In conclusion, analysis of the distribution of MBP in rat uterus revealed a marked difference in the response of the cervix and horn to a hormonal environment.

Animals↗

PubMed1976

Analysis of etiologic factors in cerebral palsy with severe mental retardation. I. Analysis of gestational, parturitional and neonatal data.

We analyzed the gestational, parturitional, neonatal (GPN) histories of 281 severely mentally retarded patients with cerebral palsy to define the etiology or pathogenesis of cerebral palsy in each patient. No association between type of cerebral palsy and GPN histories was found except for an increase in spastic-athetoid patients in the breech delivery subgroup. Significant findings include: increased incidence of prematurity and postmaturity, small and large for-gestational age (GA) fetal size, a normal birthweight for GA distribution of patients with diabetic mothers, an excess of mothers greater than or equal to 35 and less than or equal to 20 years old, an increased immediately-previous sib interval of 2.59 years suggestive of an "infertility factor", an unremarkable GPN history in one third of the cases, in another one third GPN problems not usually associated with a high risk of CNS damage, and in one third gross complications which were probably responsible for the CP, including: an increased incidence of breech deliveries, twinning, prolonged and precipitous labor and placental complications; no increased association of athetosis and Rh incompatibility or incidence of toxemia was found. Disseminated intravascular coagulation due to prenatal death of a twin may have been the cause of brain damage in several patients.

Adult↗

PubMed1995

The activity of lecithin:cholesterol acyltransferase in the serum of cows at parturition or with fatty liver.

The activity of lecithin:cholesterol acyltransferase (LCAT), which is responsible for esterification of plasma cholesterol, was evaluated in bovine serum. It was associated with the high-density lipoprotein fraction that contains apolipoprotein A-I, an activator of LCAT. In lactating cows, the activity was around 1000 U (decrease in nmol of free cholesterol per h per ml of serum), slightly higher than in 1-month-old calves. LCAT activity decreased around parturition, at which the time the serum concentrations of cholesteryl esters and free cholesterol were concomitantly decreased. A reduced LCAT activity was also found in cows with fatty livers induced by the administration of ethionine. In the cows with fatty livers, the serum concentration of cholesteryl esters was markedly decreased, whereas that of free cholesterol was only slightly decreased, thereby increasing the free- to esterified-cholesterol ratio. These results suggest that the decrease in LCAT activity may be involved in the reduction in fertility associated with fatty liver because esterification of cholesterol by LCAT is essential for its transport from the liver to peripheral tissues, such as the corpus luteum, and because cholesterol serves as the source of progesterone synthesis in the latter organ.

Animals↗

PubMed1994

Body temperatures of lambs and their mothers measured by radio-telemetry during parturition.

Using temperature-sensitive radio-telemeters chronically implanted in the abdomens of 8 fetal lambs and their mothers, we measured body temperature changes induced by parturition. Maternal body temperature rose at 0.70 +/- 0.06 degrees C/hour (mean +/- SEM) in the final stages of labour. Fetal body temperature also rose, but at a significantly lower rate, 0.45 +/- 0.06 degrees C/hour (p < 0.05). The fetus appears to be protected from excessive hyperthermia during the birth process.

Abdomen↗

PubMed1981

Electrical activity of the bovine uterus prior to and post parturition.

Recordings of electrical activity of six different areas of the uterus were obtained from two pregnant cows before and after delivery of their calves. Periods of activity occurred as spike bursts of potentials which occupied 52% of the recording time before delivery and 92% at the expulsive phase. The mean duration of the bursts was nearly doubled in the last ten hours prior to parturition without changes in their frequency. After delivery, the activity of the uterus occupied 29% of the recording time and consisted of long-lasting periods of spike bursts whose frequency was nearly halved. The alternation of periods of activity and quiescence represents the basic motility pattern of the pregnant uterus. Periods of quiescence are shortened at the time of expulsion and become predominant in the empty uterus, a phenomenon paralleled by changes in the temporal organisation of the number of spike bursts with the periods of activity.

Action Potentials↗

PubMed1977

The relationship of mammary temperature to parturition in human subjects.

Four hundred and seventy thermography studies were performed on 210 women to measure mammary temperature prior to, during, and immediately following pregnancy. Mean mammary temperature of 33.3 +/- 0.1 degrees C. (S.E.M.) obtained in 14 nonpregnant patients increased to 34.2 +/- 0.1 C. (S.E.M.) by nine weeks of gestation (p less than 0.01). The difference between mammary and sternal temperature was negative in the nonpregnant state and became positive after 18 weeks of pregnancy. Mammary temperature remained significantly higher in the pregnant group than in the nonpregnant group (p less than 0.001) up to term. In six postpartum patients, a further increase from prepartum values to 35.4 +/- 0.6 degrees C. (S.E.M.) occurred. The results suggest that relatively large changes in mammary blood flow and/or metabolic rate take place in human subjects in early pregnancy and on the day following parturition.

Body Temperature↗

PubMed1977

Multiphasic prolactin secretion during parturition in human subjects.

Prolactin (PRL) secretion in the periparturitional period in patients undergoing labor and vaginal delivery follows a remarkable multiphasic pattern not found in patients who underwent elective cesarean section without labor. There is a highly significant decline in PRL levels during active labor which reaches a nadir about two hours prior to delivery. Immediately after delivery, a surge of PRL is noted, reaching peak levels within two hours post partum. Thereafter, PRL levels fall, reaching a second nadir about nine hours post partum, and this low level is maintained for nine to 24 hours after delivery. This multiphasic pattern of PRL secretion is not correlated with changes in serum concentrations of cortisol, progesterone, estradiol, or estrone. PRL levels in all pregnant patients at term were unaffected by the administration of synthetic narcotic analgesic agents, anesthesia, or the stress of operation. It is concluded that PRL secretion in the pregnant patient at term is unresponsive to usual stimuli and that the multiphasic pattern of PRL secretion uniquely found with labor and vaginal delivery may be associated with dopaminergic neuroendocrine processes during human parturition.

Delivery, Obstetric↗

PubMed1977

Cyclic 3',5' -adenosine monophosphate in umbilical cord and maternal plasma before and after the onset of parturition.

Significant arteriovenous differences in cord cyclic 3',5'-adenosine monophosphate (cAMP) levels and between the maternal plasma (MP) and each cord vessel (mean umbilical artery [UA] greater than umbilical vein [UV] greater than MP) was observed. cAMP levels were significantly higher in the umbilical cord vessels and maternal plasma after vaginal delivery than they were following delivery by elective cesarean section before the onset of labor. The higher mean cAMP levels observed after parturition appeared to be more pronounced in the fetoplacental unit than in the maternal compartment. A significant positive correlation in cAMP levels between the UA and UV was also observed.

Cesarean Section↗

PubMed1979

20 alpha-Hydroxysteroid oxidoreductase activity and 20 alpha-dihydroprogesterone concentration in human placenta before and after parturition.

The objective of this investigation was to determine if decreased biosynthesis or increased catabolism of progesterone (P) during labor was responsible for the decreased concentration of hormone observed in the human placenta after labor and vaginal delivery. No significant difference was found in P biosynthesis by placental tissues examined before and after labor as evidenced by a similar activity of 3 beta-hydroxysteroid dehydrogenase: delta 5-isomerase. In contrast, there was a marked increase in P catabolism during labor, as shown by a significant (p less than 0.05) change in placental 20 alpha-hydroxysteroid oxidoreductase activity which increased from 835.5 +/- 103 (mean +/- SEM) pmoles of 20 alpha-dihydroprogesterone (20 alpha-DHP) generated per milligram of protein per hour before labor to 1,160.4 +/- 101 pmoles/mg/hr after labor. A similar significant (p less than 0.02) increase in enzyme activity was noticed in parallel assays of the reverse (20 alpha-DHP leads to P) reaction. As a consequence of increased P catabolism, placentas after labor had a 20 alpha-DHP concentration of 63.7 +/- 9.5 (mean +/- SEM) ng/mg protein, a value which was significantly (p less than 0.05) larger than that found before labor (37.8 +/- 8.3 ng/mg protein). These changes resulted in a modification of the placental tissue P/20 alpha-DHP ratio which decreased from 2/1 before to 1/1 after labor. The results indicate that the catabolism of P to 20 alpha-DHP increases significantly during human parturition. This phenomenon may be of importance in the mechanism of initiation and continuation of labor.

20-Hydroxysteroid Dehydrogenases↗

PubMed1980

Total uterine impulse and cervical resistance at parturition.

Resistance to the passage of the fetus during parturition has been estimated indirectly by calculation of the active contraction area during the first stage of labor until the cervix reaches a dilatation of 5 cm--the period of cervical resistance. Parturients with a high total uterine impulse in this period were studied. Two different patterns of cervical resistance with corresponding clinical pictures were found. Type I had a high frequency of cesarean sections with a good correlation to the resistance. With high resistance there also was a tendency to low Apgar scores at 1 minute. Type II had normal 1 minute Apgar scores and only vaginal deliveries.

Apgar Score↗

PubMed1981

Demonstration of novel compounds in human fetal tissues and a consideration of their possible role in parturition.

A study of a new group of compounds and their possible relevance to human parturition is presented. These compounds behave chemically and chromatographically like steroids and have been tentatively identified as analogues of 11-hydroxypregnenolone. Determined by radioenzymatic assay, highest levels were found in the fetal zone of the fetal adrenal and were about 100 times those of fetal serum. Umbilical cord levels were higher after spontaneous labor than after elective cesarean section or induced labor in premature as well as mature infants. It is hypothesized that a fetal factor distinct from adrenocorticotropic hormone acts on the adrenal cortex, particularly the fetal zone, to stimulate 11 beta-hydroxylation of nonglucocorticoid corticosteroids and that these steroids and their metabolites are excreted via the urine into the amniotic fluid. Thus they would reach the membranes and decidua where they might complete with progesterone for receptor sites, decreasing lysosomal stability with the resultant production of prostaglandins and the onset of labor.

11-Hydroxycorticosteroids↗