What are the essential components of antenatal care? A systematic review of the literature and development of signal functions to guide monitoring and evaluation.

BACKGROUND: Antenatal care (ANC) is one of the key care packages required to reduce global maternal and perinatal mortality and morbidity. OBJECTIVES: To identify the essential components of ANC and develop signal functions. SEARCH STRATEGY: MESH headings for databases including Cinahl, Cochrane, Global Health, Medline, PubMed and Web of Science. SELECTION CRITERIA: Papers and reports on content of ANC published from 2000 to 2020. DATA COLLECTION AND ANALYSIS: Narrative synthesis of data and development of signal function through 7 consensus-building workshops with 184 stakeholders. MAIN RESULTS: A total of 221 papers and reports are included from which 28 essential components of ANC were extracted and used to develop 15 signal functions with the equipment, medication and consumables required for implementation of each. Signal functions for the prevention and management of infectious diseases (malaria, HIV, tuberculosis, syphilis and tetanus) can be applied depending on population disease burden. Screening and management of pre-eclampsia, gestational diabetes, anaemia, mental and social health (including intimate partner violence) are recommended universally. Three signal functions address monitoring of fetal growth and wellbeing, and identification and management of obstetric complications. Promotion of health and wellbeing via education and support for nutrition, cessation of substance abuse, uptake of family planning, recognition of danger signs and birth preparedness are included as essential components of ANC. CONCLUSIONS: New signal functions have been developed which can be used for monitoring and evaluation of content and quality of ANC. Country adaptation and validation is recommended.

Introduction to the special issue on supersonic jet noise.

This editorial's goals are (1) to highlight a few key developments in supersonic jet and launch vehicle noise research over the past several decades while describing some of the critical modern requirements facing government and industry organizations and (2) to summarize the contributions of the articles in this Supersonic Jet Noise special issue in the context of these developments and requirements.

Non-spherical particle size estimation using supervised machine learning.

The inverse scattering problem of non-spherical particle size estimation is solved using a series of supervised machine learning models trained on a library of light scattering data. By establishing a large library with spheres and spheroids as fundamental shapes and through optimization of model hyperparameters, the trained models are able to accurately estimate a precise equivalent volume sphere radius of particles from an external database and simulations, with root mean square errors of 2.6% and 1.9% for the external and simulated particles, respectively. It was found that classification via a k-nearest neighbor model and refinement via a trained ensemble regression model performed best for equivalent volume measurements.

Effect of weaning age on growth, mammary gland development, and immune function in Holstein Friesian calves fed conserved alfalfa (FiberStart).

This study aimed to evaluate intake, body growth, and the development of the rumen, mammary gland, and immune system in Holstein Friesian calves reared for 100 d on the commercially available feed FiberStart (conserved alfalfa, Medicago sativa; Fiber Fresh Feeds Ltd., Reporoa, New Zealand) and fed calf milk replacer (CMR) for either 56 or 91 d. Eighty calves (40 bulls and 40 heifer calves) were reared indoors in groups (n = 5 of the same sex/pen). All calves were fed 4 L of CMR/d (175 g/L of CMR) in 2 feeds/d for the first 10 d and then 1 feed/d until d 49 or 84. The calves were gradually weaned by d 56 (earlier weaned; n = 8 pens) and d 91 (later weaned; n = 8 pens). All calves were fed FiberStart ad libitum as the only solid feed source from d 1 to 100 of the study. Irrespective of treatment, all calves had similar body weights at d 0 (40.9 ± 3.0 kg) and d 49 (74.2 ± 5.1 kg) of the study. Calf sex had no effect on intake, growth, blood, and immune system parameters. Earlier-weaned calves consumed 18% more solid feed dry matter but had 16% lower body weight gain (28.9 vs. 38.5 kg, respectively) from d 56 to 100 relative to later-weaned calves, resulting in different body weight at 100 d (104 vs. 121 ± 1.3 kg). Although earlier-weaned calves could compensate for the loss of CMR dry matter and crude protein intake from d 56 to 100 by increasing forage intake, they were unable to compensate for the loss of energy from the CMR by increasing solid feed consumption. Plasma ß-hydroxybutyrate concentrations were 52% greater in earlier-weaned calves than in later-weaned calves at d 84, indicating greater metabolic activity of the rumen wall. The duration of CMR feeding had no influence on humoral or cell-mediated immune functions of the calves, as evidenced by a lack of effect on antivaccine antibody responses as well as on immune gene expression. Earlier- versus later-weaned heifer calves had 5% lower mammary gland mass, indicating that greater energy supply increased mammary mass. The results of this experiment demonstrate the ability to artificially rear dairy calves on a conserved alfalfa as the only solid feed. Furthermore, earlier weaning off CMR promotes solid feed intake and an associated increase in blood ß-hydroxybutyrate, an indicator of rumen development, but increasing the duration of CMR feeding improves growth and mammary gland mass by d 100. The implications of these findings on lifetime growth, health, and milk production in dairy heifers warrant further investigation.

Milk production and composition, nitrogen utilization, and grazing behavior of late-lactation dairy cows as affected by time of allocation of a fresh strip of pasture.

Eighty late-lactation dairy cows were used to examine the effects of allocating a new pasture strip of a sward based on ryegrass (Lolium perenne L.) in the morning (a.m.; ∼0730 h) or in the afternoon (p.m.; ∼1530 h) on milk production and composition, nitrogen (N) utilization, and grazing behavior. Cows grazed the same pasture strips for 24 h and were offered the same daily herbage allowance. Herbage composition differed among treatments; p.m. herbage had greater dry matter (DM; 22.7 vs. 19.9%), organic matter (OM; 89.5 vs. 88.9%), and water-soluble carbohydrate (10.9 vs. 7.6%) concentrations and lesser crude protein (20.5 vs. 22.2%) and neutral detergent fiber (48.8 vs. 50.4%) concentrations compared with a.m. herbage. Total fatty acids (FA), α-linolenic acid, and polyunsaturated FA (PUFA) were greater in a.m. herbage, whereas monounsaturated FA were greater in p.m. herbage. Estimates of herbage DM intake did not differ among treatments. Daily milk yields and milk fat and milk protein concentrations were similar among treatments, whereas milk fat (684 vs. 627 g/cow), milk protein (545 vs. 505 g/cow), and milk solids (milk fat + milk protein) yields (1,228 vs. 1,132 g/cow) tended to be greater for cows on p.m. herbage. Rumenic acid and total PUFA in milk were greater for cows on a.m. herbage, whereas oleic acid was greater for cows on p.m. herbage. Estimates of urinary N excretion (g/d) did not differ among treatments, but urinary N concentrations were greater for cows on a.m. herbage (5.85 vs. 5.36 g/L). Initial herbage mass (HM) available (kg of DM/ha) and instantaneous HM disappearance rates (kg of DM/ha and kg of DM/h) did not differ, but fractional disappearance rates (0.56 vs. 0.74 per hour for a.m. vs. p.m., respectively) differed. Under the current conditions, timing of pasture strip allocation altered the herbage nutrient supply to cows; allocating a fresh strip of pasture later in the day resulted in moderate increases in milk and milk solids yields in late-lactation dairy cows. Conversely, a greater concentration of precursor FA in a.m. herbage resulted in a greater concentration of beneficial FA in milk, compared with cows on p.m. herbage.

Sustained perceptual invisibility of solid shapes following contour adaptation to partial outlines.

Contour adaptation (CA) is a recently described paradigm that renders otherwise salient visual stimuli temporarily perceptually invisible. Here we investigate whether this illusion can be exploited to study visual awareness. We found that CA can induce seconds of sustained invisibility following similarly long periods of uninterrupted adaptation. Furthermore, even fragmented adaptors are capable of producing CA, with the strength of CA increasing monotonically as the adaptors encompass a greater fraction of the stimulus outline. However, different types of adaptor patterns, such as distinctive shapes or illusory contours, produce equivalent levels of CA suggesting that the main determinants of CA are low-level stimulus characteristics, with minimal modulation by higher-order visual processes. Taken together, our results indicate that CA has desirable properties for studying visual awareness, including the production of prolonged periods of perceptual dissociation from stimulation as well as parametric dependencies of that dissociation on a host of stimulus parameters.

Laser velocimetry with fluorescent dye-doped polystyrene microspheres.

Simultaneous Mie scattering and laser-induced fluorescence (LIF) signals are obtained from individual polystyrene latex microspheres dispersed in an air flow. Microspheres less than 1 µm mean diameter were doped with two organic fluorescent dyes, Rhodamine B (RhB) and dichlorofluorescein (DCF), intended either to provide improved particle-based flow velocimetry in the vicinity of surfaces or to provide scalar flow information (e.g., marking one of two fluid streams). Both dyes exhibit measureable fluorescence signals that are on the order of 10(-3) to 10(-4) times weaker than the simultaneously measured Mie signals. It is determined that at the conditions measured, 95.5% of RhB LIF signals and 32.2% of DCF signals provide valid laser-Doppler velocimetry measurements compared with the Mie scattering validation rate with 6.5 W of 532 nm excitation, while RhB excited with 1.0 W incident laser power still exhibits 95.4% valid velocimetry signals from the LIF channel. The results suggest that the method is applicable to wind tunnel measurements near walls where laser flare can be a limiting factor and monodisperse particles are essential.

Adults with intellectual disabilities and challenging behaviour: the costs and outcomes of in- and out-of-area placements.

BACKGROUND: People with severe challenging behaviour are vulnerable to exclusion from local services and removal to out-of-area placements if locally available supported accommodation is insufficient to meet their needs. There are concerns about the high costs and potentially poorer outcomes of out-of-area placements but relatively little is known about how costs and outcomes compare with provision for a similar population placed locally. METHODS: Costs, quality of care and a wide range of quality of life outcomes for 38 people with intellectual disabilities and challenging behaviour living in-area and 38 similar people living out-of-area were compared. The two groups were matched as far as possible on risk factors for out-of-area placement. The out-of-area group represented two-thirds of the total number of people who originated from the territory served by the largest specialist health service in Wales and were placed in residential settings at least 10 miles beyond its boundaries. RESULTS: There was a mixed pattern of quality of care and quality of outcome advantages between the two types of setting, although in-area placements had a greater number of advantages than out-of-area placements. Unexpectedly, out-of-area placements had lower total costs, accommodation costs and daytime activity costs. CONCLUSIONS: No overall conclusion could be reached about cost-effectiveness. A number of potential reasons for the differences in cost were identified. Although additional resources may be needed to provide in-area services for those currently placed out-of-area, government policy to provide comprehensively for those who want to live locally, irrespective of their needs, appears to be attainable.

Prevalence of bacterial vaginosis in Grenadian women of reproductive age.

OBJECTIVES: To determine the prevalence of bacterial vaginosis (BV) among Grenadian women of reproductive age using the routinely collected Pap smear data for the period January 2009 to December 2011. METHODS: A retrospective review of a cross-section of Pap smears was obtained for women between the ages of 15 and 49 years, using the national centralized data bank at the General Hospital in St George's, Grenada. Women aged younger or older than the sample group, as well as those who were reported as being menopausal or hysterectomized were excluded from the study. Demographic and laboratory data were collected and descriptive statistics reported. RESULTS: The prevalence of BV was 19.5% for the three-year period among the 2677 females included in the analysis with the 20-29-year age group having the largest percentage of infection (43.6%). An increase in the trend of prevalence between 2009 (16.1%) and 2011 (21.4%) was also observed. Candida vaginalis and Trichomonas vaginalis were present in 3.6% and 0.85%, respectively. Additionally, atypical cells of unknown significance and cervical dysplasia were documented in 5.3% and 1.8% of the smears, respectively. CONCLUSION: Practicing physicians in Grenada need to consider increased screening for BV in women who may present with non-specific symptoms. Further research is necessary to determine the predisposing factors in Grenadian women and associations with the disease and to assist in the development of national education programmes to alter behavioural practices that could result in the acquisition and persistence of BV among women of reproductive age in Grenada.

Vacuolation of sensory ganglion neuron cytoplasm in rats with long-term exposure to organophosphates.

Cytoplasmic vacuolation of sensory neurons has been reported to occur within the dorsal root ganglia in studies investigating various neuropathic conditions including the effects of neurotoxic chemicals. In this study, we investigated this lesion in adult (98-119 days old) male Long-Evans rats, after multiple exposures to two organophosphates (tri-ortho-tolyl phosphate [TOTP] and chlorpyrifos) and the modifying effects of concurrent corticosterone. Tri-ortho-tolyl phosphate was administered by gavage (75, 150, or 300 mg/kg) every other day between days 14 and 28 and between days 49 and 63, chlorpyrifos (60 mg/kg) was administered subcutaneously on days 7 and 42, and corticosterone was provided in the drinking water throughout the study at a concentration of 400 microg/mL. Although relatively uncommon, there was an increase in frequency of cytoplasmic vacuoles seen in treatment groups having multiple exposures to TOTP. They were characterized as peripherally located, single-limiting membrane-bound structures in the neuronal perikarya. There was no associated cell death, even when vacuoles were large. This is the initial report of an association of this change following exposure to neurotoxic organophosphates.

Towards a novel haemoglobin-based oxygen carrier: Euro-PEG-Hb, physico-chemical properties, vasoactivity and renal filtration.

Blood transfusion is still a critical therapy in many diseases, traumatic events and war battlefields. However, blood cross-matching and storage may limit its applicability, especially in Third World countries. Moreover, haemoglobin, which in red blood cells is the key player in the oxygen transport from lung to tissues, when free in the plasma causes hypertension and renal failure. This investigation was aimed at the development of a novel haemoglobin-based oxygen carrier with low vasoactivity and renal filtration properties. Human haemoglobin was chemically conjugated with polyethylene glycol (PEG) under either aerobic or anaerobic conditions, following different chemical procedures. The resulting PEGylated haemoglobin products were characterized in terms of oxygen affinity, cooperativity, effects of protons and carbon dioxide concentration, and oxidation stability, and were transfused into rats to evaluate vasoactivity and renal filtration. A deoxyhaemoglobin, conjugated with seven PEG and seven propionyl groups, which we called Euro-PEG-Hb, did not produce profound hypertension, was 99% retained within 6 h, and exhibited oxygen binding properties and allosteric effects more similar to human haemoglobin A than the other tested PEGylated haemoglobin derivatives, thus appearing a very promising candidate as blood substitute.

Acceptability of blood and blood substitutes.

Alternatives to donor blood have been developed in part to meet increasing demand. However, new biotechnologies are often associated with increased perceptions of risk and low acceptance. This paper reviews developments of alternatives and presents data, from a field-based experiment in the UK and Holland, on the risks and acceptance of donor blood and alternatives (chemical, genetically modified and bovine). UK groups perceived all substitutes as riskier than the Dutch. There is a negative association between perceived risk and acceptability. Solutions to increasing acceptance are discussed in terms of implicit attitudes, product naming and emotional responses.

High energy proton induced radiation damage of rare earth permanent magnet quadrupoles.

Permanent magnet quadrupoles (PMQs) are an alternative to common electromagnetic quadrupoles especially for fixed rigidity beam transport scenarios at particle accelerators. Using those magnets for experimental setups can result in certain scenarios, in which a PMQ itself may be exposed to a large amount of primary and secondary particles with a broad energy spectrum, interacting with the magnetic material and affecting its magnetic properties. One specific scenario is proton microscopy, where a proton beam traverses an object and a collimator in which a part of the beam is scattered and deflected into PMQs used as part of a diagnostic system. During the commissioning of the PRIOR (Proton Microscope for Facility for Antiproton and Ion Research) high energy proton microscope facility prototype at Gesellschaft für Schwerionenforschung in 2014, a significant reduction of the image quality was observed which was partially attributed to the demagnetization of the used PMQ lenses and the corresponding decrease of the field quality. In order to study this phenomenon, Monte Carlo simulations were carried out and spare units manufactured from the same magnetic material-single wedges and a fully assembled PMQ module-were deliberately irradiated by a 3.6 GeV intense proton beam. The performed investigations have shown that in proton radiography applications the above described scattering may result in a high irradiation dose in the PMQ magnets. This did not only decrease the overall magnetic strength of the PMQs but also caused a significant degradation of the field quality of an assembled PMQ module by increasing the parasitic multipole field harmonics which effectively makes PMQs impractical for proton radiography applications or similar scenarios.

Genetically driven brain serotonin deficiency facilitates panic-like escape behavior in mice.

Multiple lines of evidence implicate brain serotonin (5-hydroxytryptamine; 5-HT) system dysfunction in the pathophysiology of stressor-related and anxiety disorders. Here we investigate the influence of constitutively deficient 5-HT synthesis on stressor-related anxiety-like behaviors using Tryptophan hydroxylase 2 (Tph2) mutant mice. Functional assessment of c-Fos after associated foot shock, electrophysiological recordings of GABAergic synaptic transmission, differential expression of the Slc6a4 gene in serotonergic neurons were combined with locomotor and anxiety-like measurements in different contextual settings. Our findings indicate that constitutive Tph2 inactivation and consequential lack of 5-HT synthesis in Tph2 null mutant mice (Tph2-/-) results in increased freezing to associated foot shock and a differential c-Fos activity pattern in the basolateral complex of the amygdala. This is accompanied by altered GABAergic transmission as observed by recordings of inhibitory postsynaptic currents on principal neurons in the basolateral nucleus, which may explain increased fear associated with hyperlocomotion and escape-like responses in aversive inescapable contexts. In contrast, lifelong 5-HT deficiency as observed in Tph2 heterozygous mice (Tph+/-) is able to be compensated through reduced GABAergic transmission in the basolateral nucleus of the amygdala based on Slc6a4 mRNA upregulation in subdivisions of dorsal raphe neurons. This results in increased activity of the basolateral nucleus of the amygdala due to associated foot shock. In conclusion, our results reflect characteristic syndromal dimensions of panic disorder and agoraphobia. Thus, constitutive lack of 5-HT synthesis influence the risk for anxiety- and stressor-related disorders including panic disorder and comorbid agoraphobia through the absence of GABAergic-dependent compensatory mechanisms in the basolateral nucleus of the amygdala.

Methane emissions changed nonlinearly with graded substitution of alfalfa silage with corn silage and corn grain in the diet of sheep and relation with rumen fermentation characteristics in vivo and in vitro.

Feeding grain and corn silage have been proposed as practices to reduce enteric methane (CH) emissions per unit of intake from ruminants, but the inclusion level required in the diet is normally not specified. The objectives of the current study were to determine the CH emission factor (g/kg DMI) of sheep fed alfalfa silage substituted with increasing levels of corn silage or corn grain at a fixed DMI level (2% of BW) and determine its relationship with rumen fermentation characteristics and microbial community composition and with in vitro fermentation characteristics of the same diets incubated using a standard laboratory method. Romney ewe hoggets (approximately 14 mo old; = 64) were randomly allocated to 8 dietary treatments, which included chaffed alfalfa silage alone or substituted with either 25, 50, 75 or 100% corn silage or 25, 50 or 65% rolled corn grain on a DM basis. After acclimatization to the diet, DMI and CH emissions were measured from individual sheep for 2 consecutive days in open-circuit respiration chambers and a rumen sample was collected at 3 h after feeding. The same diets were also incubated in an automated in vitro gas production system for 48 h using rumen liquid of fistulated nonlactating dairy cows grazing pasture. Increasing the substitution of alfalfa silage with corn silage or corn grain in the diet of sheep resulted in a quadratic response ( < 0.01) in CH emissions per unit of DMI (CH/DMI) with either supplement. For both supplements, CH/DMI increased in mixtures of up to 50% supplement inclusion and then decreased with greater supplement inclusion, especially with corn grain inclusion, but the level did not fall below that for 100% alfalfa silage. The ratio of acetate + butyrate to propionate + valerate and the propionate proportion alone in rumen liquid were the strongest single predictors for CH/DMI in the overall data set and explained 37.1 and 32.5%, respectively, of the variation in CH/DMI. Methanogens of (21.1% of total methanogens; = 0.247) and (10.7% of total methanogens; = -0.411) clades had weak to moderate correlations with in vivo CH/DMI. There was a weak quadratic relationship ( < 0.35) between in vivo CH/DMI and the in vitro parameters of gas and CH production and total VFA, whereas there was a moderate relationship ( = -0.50) between in vivo CH/estimated rumen degradable carbohydrates and in vitro CH/DM. In conclusion, CH/DMI changed in a nonlinear fashion with increasing supplement inclusion in the alfalfa forage diet when fed at 2% of BW to sheep; however, implications on predicting its influence on greenhouse gas emissions per unit of animal product, for whole farm emissions in life cycle analysis or total national emissions in the national inventories, should be determined.

Synthesis of Fluorophore-Doped Polystyrene Microspheres: Seed Material for Airflow Sensing.

Kiton red 620 (KR620) doped polystyrene latex microspheres (PSLs) were synthesized via soap-free emulsion polymerization to be utilized as a relatively nontoxic, fluorescent seed material for airflow characterization experiments. Poly(styrene-co-styrenesulfonate) was used as the PSL matrix to promote KR620 incorporation. Additionally, a bicarbonate buffer and poly(diallyldimethylammonium chloride), polyD, cationic polymer were added to the reaction solution to stabilize the pH and potentially influence the electrostatic interactions between the PSLs and dye molecules. A design of experiments (DOE) approach was used to efficiently investigate the variation of these materials. Using a 4-factor, 2-level response surface design with a center point, a series of experiments were performed to determine the dependence of these factors on particle diameter, diameter size distribution, fluorescent emission intensity, and KR620 retention. Using statistical analysis, the factors and factor interactions that most significantly affect the outputs were identified. These particles enabled velocity measurements to be made much closer to walls and surfaces than previously. Based on these results, KR620-doped PSLs may be utilized to simultaneously measure the velocity and mixing concentration, among other airflow parameters, in complex flows.

Perfluorochemicals: their applications and benefits to cell culture.

The properties of perfluorochemical liquids, particularly their high gas solubility, enables them to be exploited in cell biotechnology. They can facilitate respiratory-gas delivery to prokaryotic and eukaryotic cells in culture; in some systems, they can stimulate production of biomass, yields of commercially important cellular products and, for plant systems, expression of totipotency. The recoverability, and hence recycleability, of perfluorochemicals from aqueous systems makes their routine use a commercially feasible option. This article reviews the applications and beneficial effects of perfluorochemicals in cultured microbial, animal and plant cells, including both aerobic and anaerobic systems.

Perfluorinated blood substitutes and artificial oxygen carriers.

Blood transfusion is a remarkably safe, routine clinical procedure. However, the need for sophisticated blood processing, storage and cross-matching, coupled with increasing concerns about the safety of blood products, has fuelled the search for safe and efficacious substitutes. Candidate materials based on modified haemoglobin (including recombinant molecules) or highly inert, respiratory gas-dissolving perfluorinated liquids (perfluorochemicals) have been developed. The latter are immiscible in aqueous systems and must, therefore, be injected as emulsions. Second-generation perfluorochemical emulsions are available and in clinical trials as temporary intravascular oxygen carriers during surgery, thereby reducing patient exposure to donor blood. One commercial product is currently under Phase III clinical evaluation, with regulatory approval expected within 1 2 years. Other biomedical applications for perfluorochemicals and their emulsions include their use as pump-priming fluids for cardiopulmonary bypass, lung ventilation fluids, anti-cancer agents, organ perfusates and cell culture media supplements, diagnostic imaging agents and ophthalmologic tools. Novel applications for perfluorochemicals as immunomodulating agents are also being explored.

Tissue-specific regulation by vitamin D status of nuclear and mitochondrial gene expression in kidney and intestine.

Vitamin D is responsible, through the actions of its metabolite, 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25-(OH)2D3], for the generation of a wide array of biological responses, particularly in the intestine, kidney, and bone. 1 alpha,25-(OH)2D3 is known to interact with its nuclear receptor to mediate the regulation of gene transcription. Although many genes and gene products have been shown to be regulated by 1 alpha,25-(OH)2D3 (e.g. calbindin-D28K in the intestine and kidney; collagen, osteocalcin,and osteopontin in bone), their recognition has been largely the result of empirical testing. In this report we have used subtractive hybridization analysis of complementary DNA libraries prepared from messenger RNA (mRNA) isolated from the intestine and kidney of vitamin D-replete or vitamin D-deficient chicks to identify genes for novel proteins whose steady state mRNA levels are regulated by dietary vitamin D status. In the kidney we observed the down-regulated expression of at least seven mitochondrially encoded transcripts and the up-regulated expression of five nuclear encoded genes, two of which are metallothionein and the beta-subunit of aldolase. In the intestine, six mitochondrially encoded transcripts are up-regulated, and seven nuclear encoded transcripts were either up- or down-regulated. Thus, in addition to identifying new nuclear encoded genes whose mRNAs are regulated by vitamin D status, our approach has demonstrated the tissue-specific regulation of mitochondrial gene expression in the intestine and kidney.

Time-trend analysis of plasma cortisol concentrations in the fetal sheep in relation to parturition.

Using a cortisol RIA carefully validated for specificity in fetal ovine plasma, we studied plasma cortisol time-trend changes in eight chronically catheterized sheep fetuses in the last 22 days of gestation before the spontaneous onset of labor. Best fit exponential type curves were drawn for each individual fetus to define the time before the onset of labor at which fetal plasma cortisol was rising at different rates. Fetal plasma cortisol increased at a rate of 0.5 ng ml-1 day-1 as early as 17.1 days before labor in one fetus, whereas the mean value for all eight fetuses occurred 11.8 +/- 1.0 (SEM) days before labor. The rate of increase doubled to 1.0 ng cortisol ml-1 day-1 as early as 14.4 days before labor in one fetus, whereas the mean value for all eight fetuses occurred 9.3 +/- 0.9 days before labor. These findings suggest that the regulatory mechanisms responsible for the prelabor increase in fetal cortisol production are activated earlier in gestation than we previously thought.