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PubMed2000

Biochemical markers of bone formation and resorption around parturition and during lactation in dairy cows with high and low standard milk yields.

Substantial changes occur in skeletal metabolism during lactation. These dynamic changes are monitored with biochemical bone markers. The goal of the present study was to follow these changes in lactating cows and to investigate whether cows with a higher milk yield have a higher mobilization rate of calcium from bone. Hydroxyproline, deoxypyridinoline, pyridinoline, and the carboxyterminal telopeptide of type I collagen (ICTP) were chosen as markers for bone resorption, whereas osteocalcin was used as a bone formation marker. Urine and blood samples were collected from cows with a mean standard milk yield of 4900 and 6500 kg, respectively, 14 d before, and 14 d, 1 mo, 1.5 mo, and monthly after parturition. Urinary hydroxyproline, deoxypyridinoline, and pyridinoline concentrations increased with time, but no differences between the two groups were evident. Concentrations of 1,25-dihydroxy vitamin D and ICTP of the two groups showed an increase 14 d after parturition. Furthermore, using multivariate regression models with age and milk yield as covariates, ICTP concentrations were higher in the group with a higher milk yield. In contrast, osteocalcin concentrations decreased 14 d after parturition and returned to prepartum values 1 mo after parturition. The increase of ICTP concentrations in both groups indicates that bone was substantially resorbed. At the same time, probably less Ca was embedded in bone, as indicated by the decrease of the osteocalcin concentrations. In conclusion, cows showed increased bone resorption around parturition, and cows with higher milk yield mobilize calcium more actively from bone than cows with lower milk yield.

Animals↗
PubMed2002

Effects of day relative to parturition and dietary crude protein on rumen fermentation in prepartum transition cows.

Twelve Holstein cows and eight heifers were used in a randomized block design to examine changes in rumen fermentation and blood metabolites as animals fed diets containing 9.1 (low protein, LP) or 11.2% crude protein (moderate protein, MP) approached parturition. Animals were blocked by expected calving date and parity. Diets were isocaloric (1.58 Mcal/kg of dry matter), and the difference in dietary crude protein was achieved by the addition of urea. Diets were fed as total mixed rations for ad libitum intake. Dry matter intake decreased from 12.2 kg/d on d -21 to 9.1 kg/d on d -1 relative to parturition and was unaffected by dietary crude protein or parity. Rumen ammonia concentrations were higher for animals fed the MP diet compared with those fed the LP diet (1.8 vs. 3.7 mM). In situ neutral detergent fiber disappearance was not affected by dietary crude protein after 8 h of incubation, but it did decrease from 25.8% on d -21 to 23.3% on d -1. After 16, 24, and 48 h of incubation, neutral detergent fiber disappearance was greater for animals consuming MP than for animals consuming LP (30.6 vs. 34.4%, 37.0 vs. 44.1%, and 57.9 vs. 65.1%, respectively). There was a parity x treatment interaction after 48 h of incubation. Fiber disappearance was 55.7 or 65.9% for heifers and 60.0 or 64.7% for cows fed LP or MP, respectively. The solids rate of passage was not affected by treatment, parity, or day relative to parturition. Concentrations of plasma nonesterified fatty acid (NEFA) increased from 218 microEq/L on d -21 to 619 microEq/L on d -1. There was an interaction between day relative to parturition and parity on NEFA concentrations. Heifers had plasma NEFA concentrations of 272 and 772 microEq/L on d -21 and -1, respectively. Cows had NEFA concentrations of 164 and 467 microEq/L on d -21 and -1, respectively. Plasma glucose concentrations were affected by parity (65.8 and 58.8 mg/dl for heifers and cows). Plasma urea, NEFA, beta-hydroxybutyrate, and glucose concentrations were not affected by dietary treatment. In conclusion, heifers tended to have higher plasma concentrations of NEFA and glucose, but did not have elevated concentrations of beta-hydroxybutyrate. Rumen fermentation was relatively unaffected by day relative to parturition, but feeding less than 11% crude protein to prefresh transition cows may limit ruminal fiber degradation.

3-Hydroxybutyric Acid↗
PubMed1976

Production and turnover of IgG1 and IgG2 immunoglobulins in the bovine around parturition.

Production rates (entry rate into blood plasma) and other metabolic parameters for the IgG1 and IgG2 subclasses of immunoglobulins in mammary secretions (ratio of about 7 to 1) were determined in cows around the time of parturition by both single-injection and continuous-infusion isotope-dilution techniques. Four cows were given a single dose of 150 to 200 muCi of iodine-125 labeled IgG1 and 100 to 250 muCi of iodine-131 labeled IgG2 at 2 to 1 wk before parturition. Four cows, including two of the above, were infused continuously with constant amounts of the labeled immunoglobulins starting at 11 to 4 days before parturition. All cows were maintained until 4 to 6 days after parturition for monitoring the specific activities of iodine-125 labeled IgG1 and iodine-131 labeled IgG2 in the plasma and mammary secretions. Maximum entry rates of IgG1 and IgG2 were between 3 and 1 day prepartum with means of 125 and 60 g/500 kg body weight per day. The exchangeable pool means for IgG1 and IgG2 were 619 and 643 g/500 kg body weight, and both immunoglobulins were divided almost equally between the intra- and extravascular pools. A greatly increased production and a shortened half-life or greater turnover for plasma IgG1 occurs around the time of parturition which can account for the large accumulation of IgG1 in colostrum.

Animals↗
PubMed1983

Relationships among type of parturition, type of discharge from genital tract, involution of cervix, and subsequent reproductive performance in Holstein cows.

Data were from 492 Holstein cows calved between October, 1976, and May, 1977, in eight herds in Michigan. Diameter of the cervix of each cow was estimated by palpation at 8 to 21 days postpartum and again 2 wk later. Parturition and postpartum discharge from the genital tract were classified as normal or abnormal. Size of the cervix between 12 and 26 days postpartum was classified as small, medium, or large within two parity groups. Incidence of abnormal parturition and incidence of abnormal postpartum discharge were 14.1 and 38.0%. Involution of the cervix was affected by parity and type of postpartum discharge. Involution of the cervix occurred sooner postpartum in primiparous than in multiparous cows and sooner postpartum in cows with normal discharge than in cows with abnormal discharge. The greatest difference in cervix diameter between cows with normal or abnormal discharges was 10 mm at 3 wk postpartum. Days from parturition to first detected estrus and first service were extended by abnormal postpartum discharge but not by abnormal parturition. First-service conception rate was lower and days from parturition to conception were higher in cows with medium or large cervices compared to cows with small cervices. Type of postpartum discharge and size of cervix early postpartum may be useful for predicting subsequent reproductive performance in dairy cows.

Animals↗
PubMed1984

Genetic interrelationships of parturition problems and production.

Data were 5091 calvings from 3904 cows for milk fever, retained placenta, mastitis within 48-h postpartum, calving difficulty, and 48-h calf livability collected from 27 large California dairies analyzed for genetic interrelationships among parturition problems. Heritability of each trait was small; however, retained placenta had large positive genetic correlations with milk fever (.34) and mastitis (.33). Adding difficulty-mortality classes to models to study genetic relationships of parturition problems had little effect on estimates but did influence incidence of parturition problems. With calving difficulty, incidence of milk fever increased by 4.9% and retained placenta by 5.3%. With calf mortality, milk fever increased by 4.4% and retained placenta by 13%. A combination of difficulty and mortality was related to a 9.6% increase of milk fever and a 20.2% increase of retained placenta. Genetic correlations of all problems with mature equivalent milk indicated that selection for increased production would be accompanied by lower incidence of retained placenta, 48-h mastitis, and milk fever. Genetic correlations of retained placenta with milk fever and 48-h mastitis were positive. Selection for increased milk yield should not increase incidence of parturition problems, and prescreening of bulls on parturition performance of daughters would be feasible.

Animals↗
PubMed2000

Cardiovascular parameters telemetrically measured during pregnancy, parturition, and lactation in a common marmoset (Callithrix jacchus).

Here we present the first report of heart rate, blood pressure, and locomotive activity of a female common marmoset (Callithrix jacchus) that was moving freely in its home cage during gestation, parturition, and lactation. We collected the data by using a miniaturized telemetry and data-acquisition system (Data Sciences, St. Paul, MN) that had been adapted for marmosets (1). The parameters were recorded continually from 12 days before to 15 days after parturition. Parturition lasted about 3.5 h, during which marked changes in heart rate, systolic blood pressure, and diastolic blood pressure occurred. To obtain control values, we again measured these parameters for 13 days during a "physiologically neutral" phase (4 months after parturition), when the female was neither pregnant nor lactating. Heart rate was 200% higher, systolic blood pressure was 25% higher, and diastolic blood pressure was 75% higher during parturition than during the neutral phase.

Animals↗
PubMed2001

Comparison of two protocols with a progesterone antagonist aglepristone (RU534) to induce parturition in bitches.

Parturition was induced in ten Beagle bitches by injecting them subcutaneously with 15 mg aglepristone kg-1 (Alizine) at day 58 of gestation and 24 h later and subsequently at 2 h intervals with either 0.08 mg alfaprostol kg-1 (Alfabedyl) (group 1; five bitches) or 0.15 iu oxytocin kg-1 (Ocytocine S) (group 2; five bitches). Blood samples were collected every 4 h until the end of parturition to assay plasma concentrations of progesterone, dihydro-keto prostaglandin F2 alpha (PGFM), oxytocin, prolactin and cortisol. Parturition occurred in all bitches. The mean time of onset of parturition for both groups was not significantly different (32.6 +/- 3.7 h for group 1 versus 31.6 +/- 3.6 h for group 2), although the mean expulsion time for bitches from group 2 (4.5 +/- 1.8 h) was significantly shorter than that of bitches in group 1 (9.1 +/- 2.0 h). At birth, 93% of the pups were alive in group 2 compared with 86% in group 1. Peripheral plasma concentrations of progesterone increased significantly after the administration of aglepristone, but direct or indirect luteolysis was not induced, and plasma concentrations of oxytocin or cortisol did not change during the first 24 h after administration of aglepristone. PGFM concentrations increased significantly after 4 h of aglepristone administration. During the first 20 h after aglepristone administration, prolactin concentrations increased significantly. At parturition, bitches in group 2, which had the shorter expulsion time of pups, were characterized by significantly higher concentrations of oxytocin and PGFM than bitches in group 1.

Animals↗
PubMed1990

[Changes in free amino acid serum levels in swine during parturition and in piglets during birth].

During the course of parturition seven high pregnant sows, crossbreds of the Large White and Landrace breeds, and their 69 piglets being born, were studied for the changes of the total and separate free amino acids in the blood plasma in relation to the time of duration of the parturition, to the sequence of piglets being born in the litter, and to the birth weight of the piglets. The concentration of the total free amino acids in blood plasma is 2.44 +/- 0.182 mmol.l-1 just before parturition; after the birth of the last piglet it decreases insignificantly to 2.17 +/- 0.190 mmol.l-1. The concentration of the total free amino acids in the blood plasma of newborn piglets is always significantly higher than in their mothers (p less than 0.001) and is 4.24 +/- 0.109 mmol.l-1. The rank of each piglet in the sequence of births in litter has no influence on the level of plasma concentration of the total free amino acids amino acidaemia was 4.03 +/- 0.268 mmol.l-1 in the piglets born first and insignificantly changed to 3.99 +/- 0.445 mmol.l-1 of blood plasma in the last piglets born in the litter. The time factor of parturition is also statistically insignificant. However, the differences in the free "amino acids" concentration in the blood plasma between the piglets with the lowest weight and the piglets with a weight of up to 1200 and 1500 g are statistically significant (p less than 0.02). Alanine (0.43 +/- 0.052 mmol.l-1) and glycine (0.43 +/- 0.063 mmol.l-1) constitute the largest proportions of all the 17 amino acids studied in the blood plasma in the high pregnant sows before parturition. The tyrosine concentration in piglets at birth is remarkably high (1.44 +/- 0.035 mmol.l-1); it represent 34 per cent of the total amino acidaemia. Tyrosine, histidine and lysine concentration in the blood plasma is statistically highly significantly higher (p less than 0.001) in newborn piglets than in their mothers. The phenomenon of 6-times higher tyrosinaemia in piglets, compared with the sows is discussed in connection with the weight at birth and with the data on the function and concentration of thyroid hormones in piglets during the first days of their lives.

Amino Acids↗
PubMed1979

Induction of parturition in the sow with a prostaglandin analogue (I.C.I. 80996).

Parturition was induced in 112 gilts and sows on day 111,, 112, and 113 of gestation by means of a single intramuscular injection of 175 mcg of a prostaglandin F2 alpha analogue (Cloprostenol, I.C.I 80996). No side effects were detected immediately after injection and the course of the induced parturition was normal. The interval between injection and parturition was approximately 28 hours. Induction of parturition on day 113 resulted in a significant shortening of this interval as compared with day 111, and 112. The average weights of the piglets at birth and at 5 weeks were within the normal range. The percentage of stillbirths and the loss of piglets up to weaning did not differ significantly between control and experimental groups. The practical applications of induction of parturition are discussed.

Animals↗
PubMed1977

Changes in cervical function at parturition.

In sheep and goats changes in the wall of the uterine cervix associated with parturition were studied in relation to the preparturient sequence of endocrine events. Evidence was obtained of separation of collagen fibrils, possibly due to changes in the electrostatic binding of the fibrils by glycosaminoglycans. The mechanical properties of the cervix were investigated quantitatively on isolated tissues by radial loading to destruction, and by progressive extension on a tensometer; the extension experiments revealed that at parturition (but not before) the cervical wall acts mechanically as if composed of two different tissues, one of which, the collagen layer, changes profoundly at parturition to facilitate dilatation. Resistance to dilatation (compliance) was investigated in vivo using indwelling intracervical balloons which could be inflated with water at standard speed. This permitted serial observations in the same animal during the progress of parturition induced with foetal dexamethasone (sheep) or maternal cloprostenol (goats). Compliance increased progressively in all 13 parturient animals, but not in untreated controls, and this increase occurred coincidentally with the expected fall in progesterone and rise in oestrogen concentrations: it occurred before the preparturient rise in PGF. Meclofenamic acid administration to cloprostenol treated goats successfully delayed the PGF surge and delayed parturition but did not delay the increase in compliance which reached maximum within the 36 hours of treatment with the PG synthetase inhibitor.

Animals↗
PubMed1983

Clinical and endocrine studies during normal and induced parturition in mares.

Parturition was induced in 6 mares between Day 327 and 346 of pregnancy using oxytocin (Group I) and in 6 mares between Day 315 and 330 of pregnancy with fluprostenol in combination with oxytocin (Group II). A third group of 4 mares which served as controls were allowed to go to full term (322-340 days) and foal down normally. Parturition occurred within 24-102 min (mean = 61,4; SD = 31,6) in 5 of the Group I mares and within 160-185 min (mean = 173; SD = 10,86) in the mares of Group II. Expulsion of the afterbirth took place between 7 and 206 min (mean = 79; SD = 76,38) and between 7 and 73 min (mean = 37,5; SD = 21,29) in Groups I and II respectively. Three of 6 mares in the oxytocin group showed foal heat, all 3 conceived and 2 carried foals to term. Of the remaining 3 mares, 2 showed heat approximately one month after parturition, and were served and conceived but one aborted due to babsesiosis and one resorbed while the third remained in anoestrus for 3-4 months. In the combined treatment group, 3 mares showed foal heat of which only 2 were served. Both conceived and one carried a foal to term. One of the remaining mares showed oestrus 2 months after parturition while the remaining 2 mares showed oestrus approximately one month after parturition. Both were served, one conceived but subsequently resorbed.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effects of calf removal at parturition on postpartum ovarian activity in Zebu (Bos indicus) cows in the humid tropics.

To assess endocrine and morphological responses of ovaries to total weaning at parturition, 6 Zebu (Bos indicus) cows 5 years or older were investigated. Following parturition, blood samples were collected daily during the first month and twice weekly thereafter until day 60 to determine concentrations of progesterone (P4) and prostaglandin F2 alpha metabolite. It took between 25 to 32 days to complete uterine involution. The prostaglandin metabolite remained elevated for a mean period of 14.2 days (range, 4-21) postpartum. Five of the animals resumed cyclicity with a short estrous cycle starting between days 7 to 34 and lasting between 7 and 14 days. No estrous behavior was recorded prior to the short estrous cycles, but subsequent normal-length estrous cycles were all preceded by signs of estrus. In the 1 animal that resumed cyclicity with an estrous cycle of normal length on day 37 (length 20 days), the cycle was preceded by estrous behavior. Progesterone concentrations reached a mean maximum of 4.8 nmol liter-1 during the short estrous cycles, and prostaglandin metabolite concentrations peaked while P4 concentrations were decreasing. P4 concentrations reached a mean maximum of 12.2 nmol liter-1 during the estrous cycles of normal length. The interval from parturition to the first estrous cycle of normal length varied between 16 and 48 days, and the length of the cycle was 18 to 22 days. Starting 2 days postpartum, ovaries from 5 of the cows were scanned by ultrasonography every second day until day 30 postpartum. Medium-sized follicles were detected between days 4 to 7 postpartum in 4 of the scanned cows that later had short estrous cycles. The time between parturition and the appearance of the first dominant follicle was 7.6 days (range 6-10 days). The interval between parturition and the appearance of the first ovulatory-sized follicle was 10.2 days (range 8-13 days). In 3 of the scanned cows this ovulatory-sized follicle ovulated. We conclude that cyclic ovarian activity in Zebu cows can start early in the postpartum period in the absence of offspring, and that short luteal phases, not preceded by estrous behavior, may play an important role in establishing normal postpartum ovarian activity.

Animals↗
PubMed1996

Induction of parturition in alpacas and subsequent survival of neonates.

OBJECTIVE: To evaluate use of fluprostenol, dexamethasone, and oxytocin for induction of parturition in alpacas, and to determine viability of the newborn crias. DESIGN: Prospective, randomized, controlled trial. ANIMALS: 36 pregnant alpacas within 10 days of parturition. PROCEDURE: Animals were randomly assigned to treatment groups. Plasma progesterone and plasma and urine estrone sulfate concentrations were measured for 5 days after treatment. Clinical signs of the neonates were determined. RESULTS: Time between treatment and parturition was significantly shorter for animals that received fluprostenol than for animals in any other group. The highest dose of dexamethasone (0.5 mg) caused fetal death. None of the other treatments induced early parturition. Time between birth and first suckling, body weight, rectal temperature, pulse rate, and respiratory rate at birth and serum IgG concentration 24 hours after birth were not different between crias born after fluprostenol treatment and crias born to control alpacas. CLINICAL IMPLICATIONS: Fluprostenol was effective at inducing parturition in these alpacas, but dexamethasone and oxytocin were not. Crias born after fluprostenol treatment were similar to crias born to control alpacas.

Animals↗
PubMed1976

Induced parturition in cattle. 1. Clinical studies.

Parturition was induced in 17 Friesland heifers to decrease the possible occurrence of dystocia. The heifers were given 39 mg dexamethasone intra-muscularly on the 267th day of pregnancy and were observed for signs of impending parturition. The time of foetal membrane expulsion was noted. Parturition occurred on an average of 57 hours after corticosteroid administration. Three heifers required assistance during parturition. In one case a second injection of dexamethazone had to be given. The incidence of retained placenta was 68,8%. Rectal examination five to seven months after induction revealed that 76,5% of all animals were again pregnant. Of the four non-pregnant animals three had received assistance during parturition.

Animals↗
PubMed1998

Evaluation of prostaglandin F2 alpha treatment in dairy cows at risk for low fertility after parturition.

OBJECTIVE: To evaluate the effect of 2 postpartum prostaglandin F2 alpha (PGF 2 alpha) treatment protocols on reproductive performance of dairy cows at risk for low fertility. In addition, various medical conditions in cows that are recognized as having adverse effects on fertility were evaluated as criteria for fertility treatment. DESIGN: Prospective study. ANIMALS: 291 cows with, and 271 cows without, risk factors for low fertility. PROCEDURE: Cows at risk for low fertility were randomly assigned to 2 treatment groups. Group-1 cows received 3 i.m. injections of PGF2 alpha at weekly intervals after parturition, and group-2 cows received 1 i.m. injection of PGF2 alpha 17 to 24 days after parturition. RESULTS: Compared with a single PGF2 alpha treatment 17 to 24 days after parturition, there was no added benefit of 3 treatments with PGF2 alpha 3 to 10, 10 to 17, and 17 to 24 days after parturition in cows at risk for low fertility. Cows without risk factors for low fertility had 20% higher pregnancy rates, compared with cows with risk factors for low fertility. Twinning had a negative effect on future fertility. CLINICAL IMPLICATIONS: Results of this study indicate that further consideration should be given to the timing and intervals of PGF2 alpha administration after parturition. Risk factors for low fertility, such as retained placenta, twins, and assisted calvings, are valid criteria to evaluate different treatment options to improve fertility in dairy cows.

Animals↗
PubMed2003

Loss of hepatitis C virus RNA after parturition in female patients with chronic HCV infection.

It is unclear whether pregnancy has any influence on chronic hepatitis C virus (HCV) infection. The aim of this study was to investigate the relationship between pregnancy and parturition with HCV viremia levels and the natural resolution of HCV RNA. Twenty-two pregnant patients and 120 nonpregnant control female patients, both positive for anti-HCV and HCV RNA, were studied. The HCV core protein levels were quantified by enzyme immunoassay, and HCV RNA was detected by reverse transcription-polymerase chain reaction (RT-PCR). Of the pregnant group, two females whose HCV RNA was negative continuously for more than 6 months lost HCV RNA permanently after parturition, and one female whose level of HCV core protein was intermittently under the limit of detection level lost HCV RNA intermittently. In the control group, only one female lost HCV RNA persistently, and one lost HCV RNA intermittently after she developed liver cirrhosis. At 3 months after parturition, the HCV core protein level was <15 fmol/L in all patients who lost HCV RNA, while the HCV core protein level was >/=15 fmol/L in 81.3% of the patients who persistently had HCV RNA (P = 0.03). Significantly more pregnant patients lost HCV RNA than did nonpregnant controls. These findings suggest that pregnancy and parturition appear to influence the clinical course of HCV infection.

Adult↗
PubMed2006

Platelet-activating factor receptor (PAF-R) and acetylhydrolase (PAF-AH) are co-expressed in immature bovine trophoblast giant cells throughout gestation, but not at parturition.

Platelet-activating factor (PAF) was associated with successful implantation in the cow, trophoblast invasiveness and angiogenesis. Bovine placentation is characterized by the limited invasion of trophoblast giant cells (TGC) into the maternal caruncular epithelium. TGC exhibit both endocrine activity and properties of tumor cells and may thus be targets of and mediators for the action of PAF. We examined PAF-receptor (PAF-R) and PAF-acetylhydrolase (PAF-AH) gene expression and localized mRNA and corresponding proteins in bovine placentomes throughout gestation and at parturition. PAF-R and PAF-AH protein and mRNA were highly expressed and colocalized in immature TGC from early gestation until near term, while mature TGC were negative. After the onset of parturition both PAF-R and PAF-AH were expressed in the maternal stroma, predominantly endothelial cells. The expression of PAF-R and PAF-AH in immature but not mature TGC during gestation implicates a role for PAF in the differentiation, maturation and function of bovine placentomal TGC. Placentomal angiogenesis could be mediated by binding of PAF to PAF-R present in endothelial cells. The parturition-related "switch" of PAF-R and PAF-AH from TGC to the maternal stroma suggests that PAF may participate in the regulation of parturition and in prepartum tissue programming.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed2002

Neuroactive steroids, their precursors and polar conjugates during parturition and postpartum in maternal and umbilical blood: 3.3beta-hydroxy-5-ene steroids.

Five 3beta-hydroxy-5-ene steroids involved in the metabolic route from pregnenolone sulfate to dehydroepiandrosterone and its sulfate, of which three are known allosteric modulators of neurotransmitter receptors, were monitored in the serum of 20 women around parturition. In addition, their levels in maternal and umbilical serum were compared at delivery. On the basis of these data, a scheme of steroid biosynthesis in maternal organism during the critical stages around parturition is proposed. In maternal serum, all the steroids except dehydroepiandrosterone sulfate decreased during labor and even first day after delivery, although their changes were less distinct the more distant from pregnenolone sulfate (PregS) in the metabolic pathway. Calculation of product/immediate precursor ratios in maternal serum over all stages around parturition enabled identification of the respective changes in the activities of the relevant enzymes. The ratio of 17-hydroxypregnenolone/pregnenolone did not change significantly, while that of dehydroepiandrosterone/17-hydroxypregnenolone grew, indicating increased C17,20 side chain cleavage on the account of C17-hydroxylation both catalyzed by C17-hydroxylase-C17,20-lyase. As was shown by factor analysis, the changes in the maternal steroids were associated with a single common factor, which strongly correlated with all the steroids except dehydroepiandrosterone sulfate. The lack of change in the pregnenolone sulfate/pregnenolone ratio and a marked increase of the ratio dehydroepiandrosterone sulfate to unconjugated dehydroepiandrosterone indicate a different means of formation of both steroid sulfates. On the basis of these data, a scheme of steroid biosynthesis in maternal organism during the critical stages around parturition is proposed.

Female↗