Fetal Demand Research Articles

Understanding the Genetic Landscape of Gestational Diabetes: Insights into the Causes and Consequences of Elevated Glucose Levels in Pregnancy.

Background/Objectives: During pregnancy, physiological changes in maternal circulating glucose levels and its metabolism are essential to meet maternal and fetal energy demands. Major changes in glucose metabolism occur throughout pregnancy and consist of higher insulin resistance and a compensatory increase in insulin secretion to maintain glucose homeostasis. For some women, this change is insufficient to maintain normoglycemia, leading to gestational diabetes mellitus (GDM), a condition characterized by maternal glucose intolerance and hyperglycaemia first diagnosed during the second or third trimester of pregnancy. GDM is diagnosed in approximately 14.0% of pregnancies globally, and it is often associated with short- and long-term adverse health outcomes in both mothers and offspring. Although recent studies have highlighted the role of genetic determinants in the development of GDM, research in this area is still lacking, hindering the development of prevention and treatment strategies. Methods: In this paper, we review recent advances in the understanding of genetic determinants of GDM and glycaemic traits during pregnancy. Results/Conclusions: Our review highlights the need for further collaborative efforts as well as larger and more diverse genotyped pregnancy cohorts to deepen our understanding of the genetic aetiology of GDM, address research gaps, and further improve diagnostic and treatment strategies.

Relative uteroplacental insufficiency of labor.

Relative uteroplacental insufficiency of labor (RUPI-L) is a clinical condition that refers to alterations in the fetal oxygen "demand-supply" equation caused by the onset of regular uterine activity. The term RUPI-L indicates a condition of "relative" uteroplacental insufficiency which is relative to a specific stressful circumstance, such as the onset of regular uterine activity. RUPI-L may be more prevalent in fetuses in which the ratio between the fetal oxygen supply and demand is already slightly reduced, such as in cases of subclinical placental insufficiency, post-term pregnancies, gestational diabetes, and other similar conditions. Prior to the onset of regular uterine activity, fetuses with a RUPI-L may present with normal features on the cardiotocography. However, with the onset of uterine contractions, these fetuses start to manifest abnormal fetal heart rate patterns which reflect the attempt to maintain adequate perfusion to essential central organs during episodes of transient reduction in oxygenation. If labor is allowed to continue without an appropriate intervention, progressively more frequent, and stronger uterine contractions may result in a rapid deterioration of the fetal oxygenation leading to hypoxia and acidosis. In this Commentary, we introduce the term relative uteroplacental insufficiency of labor and highlight the pathophysiology, as well as the common features observed in the fetal heart rate tracing and clinical implications.

A genetically small fetus impairs placental adaptations near term.

The placenta is a gatekeeper between the mother and fetus, adapting its structure and functions to support optimal fetal growth. Studies exploring adaptations of placentae that support the development of genetically small fetuses are lacking. Here, using a mouse model of impaired fetal growth, achieved by deleting insulin-like growth factor 2 (Igf2) in the epiblast, we assessed placental nutrient transfer and umbilical artery (UA) blood flow during late gestation. At embryonic day (E) 15.5, we observed a decline in the trans-placental flux of glucose and system A amino acids (by using 3H-MeG and 14C-MeAIB), proportionate to the diminished fetal size, whereas UA blood flow was normal. However, at E18.5, the trans-placental flux of both tracers was disproportionately decreased and accompanied by blunted UA blood flow. Feto-placental growth and nutrient transfer were more impaired in female conceptuses. Thus, reducing the fetal genetic demand for growth impairs the adaptations in placental blood flow and nutrient transport that normally support the fast fetal growth during late gestation. These findings have important implications for our understanding of the pathophysiology of pregnancies afflicted by fetal growth restriction.

Non-invasive in-utero quantification of vascular reactivity in human placenta.

Placental vascular reactivity (PlVR) indicates the ability of the placental vasculature to match blood supply to fetal demand. Many pregnancy disorders alter the characteristics of PlVR, resulting in suboptimal oxygen delivery, although current understanding is limited by the lack of non-invasive, repeatable methods to measure PlVR in utero. Our objective was to quantify PlVR by measuring the placental response to transient changes in maternal carbon dioxide (CO2) using blood-oxygen-level-dependent (BOLD) magnetic resonance imaging (MRI). We hypothesized that PlVR will increase with gestational age to meet the changing demands of a growing fetus, and that PlVR will be driven by a maternal response to changes in CO2 concentration. This was a cross-sectional study of 35 women with a healthy singleton pregnancy, of whom 31 were included in the analysis. The median gestational age was 32.6 (range, 22.6-38.4) weeks. Pregnant women were instructed to follow audiovisual breathing cues during a MRI scan. Maternal end-tidal CO2 (EtCO2) was measured concurrently with resting placental BOLD MRI for a total of 7-8 min. Preprocessing of magnetic resonance images consisted of manual delineation of placental anatomy and motion correction. In each placental voxel, vascular reactivity was computed using a coherence-weighted general linear model between MRI signal and EtCO2 stimulus. Global PlVR was computed as the mean of voxel-wise PlVR values across the placenta. PlVR, quantified by the placental response to induced, transient changes in maternal CO2, was consistently measured in utero using BOLD MRI. PlVR increased non-linearly with advancing gestational age (P < 0.001) and was higher on the fetal side of the placenta. PlVR was associated positively with fetal brain volume after accounting for gestational age. PlVR did not show any significant associations with maternal characteristics. We present, for the first time, a non-invasive paradigm to quantify PlVR in ongoing human pregnancies without the use of exogenous gases or contrast agents. Our findings suggest that PlVR is driven by a fetal response to changes in maternal CO2. Ease of translation to the clinical setting makes PlVR a promising biomarker for the identification and management of high-risk pregnancies. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Characterization of placentome vascular perfusion in relation to pregnancy associated glycoproteins throughout gestation in pregnant beef heifers

During pregnancy, blood flow to the uterus changes to support fetal demand. Placentomes serve as vascular attachment sites on the placenta for exchange of gases, nutrients, and metabolic products. Non-invasive methods of ultrasonography and biomarkers have been described to assess placental health and fetal viability. Pregnancy associated glycoproteins (PAGs) are produced by the ruminant placenta and are detected in maternal circulation. In cattle, changes in circulating PAG concentrations are associated with embryonic and fetal outcomes. The objective of this study was to determine the association between placentome blood perfusion and circulating PAG concentrations as they relate to the health of the developing fetus. We hypothesized that placentome perfusion and PAG concentration will be positively correlated and associated with neonatal outcome. A prospective, observational study was designed using 26 pregnant, nulliparous, Angus heifers in which PAG concentration and placentome blood perfusion were assessed throughout gestation, with assessment of calving characteristics following parturition. Placentome blood perfusion was visualized at 30-day intervals via transrectal Doppler ultrasonography with power flow function. Ultrasound images were analyzed using ImageJ software to determine the percent area of perfusion and integrated pixel densities. Venous blood was collected and PAG concentrations were determined via serum PAG enzyme-linked immunoassay. Mean placentome blood perfusion increased as gestation advanced. PAG concentrations demonstrated the expected temporal trend, increasing with gestation length, and were positively linearly correlated with placentome perfusion (P < 0.0001). The relationship identified between circulating PAG concentration and placentome blood perfusion suggests the use of transrectal power flow Doppler ultrasonography as a noninvasive technique to determine placental blood flow morphometrics to assess conceptus wellbeing throughout pregnancy.

Differential 5'-tRNA Fragment Expression in Circulating Preeclampsia Syncytiotrophoblast Vesicles Drives Macrophage Inflammation.

The relationship between placental pathology and the maternal syndrome of preeclampsia is incompletely characterized. Mismatch between placental nutrient supply and fetal demands induces stress in the syncytiotrophoblast, the layer of placenta in direct contact with maternal blood. Such stress alters the content and increases the release of syncytiotrophoblast extracellular vesicles (STB-EVs) into the maternal circulation. We have previously shown 5'-tRNA fragments (5'-tRFs) constitute the majority of small RNA in STB-EVs in healthy pregnancy. 5'-tRFs are produced in response to stress. We hypothesized STB-EV 5'-tRF release might change in preeclampsia. We perfused placentas from 8 women with early-onset preeclampsia and 6 controls, comparing small RNA expression in STB-EVs. We used membrane-affinity columns to isolate maternal plasma vesicles and investigate placental 5'-tRFs in vivo. We quantified 5'-tRFs from circulating STB-EVs using a placental alkaline phosphatase immunoassay. 5'-tRFs and scrambled RNA controls were added to monocyte, macrophage and endothelial cells in culture to investigate transcriptional responses. 5'-tRFs constitute the majority of small RNA in STB-EVs from both preeclampsia and normal pregnancies. More than 900 small RNA fragments are differentially expressed in preeclampsia STB-EVs. Preeclampsia-dysregulated 5'-tRFs are detectable in maternal plasma, where we identified a placentally derived load. 5'-tRF-Glu-CTC, the most abundant preeclampsia-upregulated 5'-tRF in perfusion STB-EVs, is also increased in preeclampsia STB-EVs from maternal plasma. 5'-tRF-Glu-CTC induced inflammation in macrophages but not monocytes. The conditioned media from 5'-tRF-Glu-CTC-activated macrophages reduced eNOS (endothelial NO synthase) expression in endothelial cells. Increased release of syncytiotrophoblast-derived vesicle-bound 5'-tRF-Glu-CTC contributes to preeclampsia pathophysiology.

Specialist perinatal palliative care: a retrospective review of antenatal referrals to a children’s palliative care service over 14 years

BackgroundPerinatal palliative care is an emerging branch of children’s palliative care. This study sought to better understand the pattern of antenatal referrals and the role of a specialist paediatric palliative care (PPC) team in supporting families throughout the antenatal period.MethodsA single-centre retrospective chart review of all antenatal referrals to a quaternary children’s palliative care service over a 14-year period from 2007 to 2021.ResultsOne hundred fifty-nine antenatal referrals were made to the PPC team over a 14-year period, with increasing referrals over time. Referrals were made for a broad spectrum of diagnoses with cardiac conditions (29% of referrals) and Trisomy 18 (28% of referrals) being the most prevalent. 129 referrals had contact with the PPC team prior to birth and 60 had a personalised symptom management plan prepared for the baby prior to birth. Approximately one third (48/159) died in utero or were stillborn. Only a small number of babies died at home (n = 10) or in a hospice (n = 6) and the largest number died in hospital (n = 72). 30 (19% of all referrals) were still alive at the time of the study aged between 8 months and 8 years.ConclusionsSpecialist PPC teams can play an important role in supporting families during the antenatal period following a diagnosis of a life-limiting fetal condition and demand for this service is increasing. A large proportion of the cases referred will not survive to the point of delivery and a number of babies may survive much longer than predicted. PPC teams can be particularly helpful navigating the uncertainty that exists in the antenatal period and ensuring that plans are made for the full spectrum of possible outcomes.

Practice variation in timing of antenatal corticosteroid administration in early-onset fetal growth restriction: Asecondary analysis of the Dutch STRIDER study.

In early-onset fetal growth restriction the fetus fails to thrive in utero due to unmet fetal metabolic demands. This condition is linked to perinatal mortality and severe neonatal morbidity. Maternal administration of corticosteroids in high-risk pregnancies for preterm birth at a gestational age between 24 and 34 weeks has been shown to reduce perinatal mortality and morbidity. Practice variation exists in the timing of the administration of corticosteroids based on umbilical artery monitoring findings in early-onset fetal growth restriction. The aim of this study was to examine differences in neonatal outcomes when comparing different corticosteroid timing strategies. This was a post-hoc analysis of the Dutch STRIDER trial. We examined neonatal outcomes when comparing institutional strategies of early (umbilical artery pulsatility index >95th centile) and late (umbilical artery shows absent or reversed end-diastolic flow) administration of corticosteroids. The primary outcomes were neonatal mortality and a composite of neonatal mortality and neonatal morbidity, defined as bronchopulmonary dysplasia, intraventricular hemorrhage, necrotizing enterocolitis or retinopathy of prematurity. We also analyzed predictors for adverse neonatal outcomes, including gestational age at delivery, birthweight, maternal hypertensive disorders, and time interval between corticosteroids and birth. A total of 120 patients matched our inclusion criteria. In 69 (57.5%) the early strategy was applied and in 51 (42.5%) patients the late strategy. Median gestational age at delivery was 28 4/7 (± 3, 3/7) weeks. Median birthweight was 708 (± 304) g. Composite primary outcome was found in 57 (47.5%) neonates. No significant differences were observed in the primary outcome between the two strategies (neonatal mortality adjusted odds ratio [OR] 1.22, 95% CI 0.44-3.38; composite primary outcome adjusted OR 1.05, 95% CI 0.42-2.64). Only gestational age at delivery was a significant predictor for improved neonatal outcome (adjusted OR 0.91, 95% CI 0.86-0.96). No significant differences in neonatal outcomes were observed when comparing early and late strategy of antenatal corticosteroid administration on neonatal outcomes in pregnancies complicated by early-onset fetal growth restriction. We found no apparent risk contribution of interval between corticosteroid administration and delivery in multivariate analysis. Gestational age at delivery was found to be an important predictor of neonatal outcome.

Formation and Acquisition of Bone Mass: A Commitment of the Obstetrician-Gynecologist in an Interdisciplinary Program

This article provides an overview of the process of bone mass development and acquisition, starting from gestation until reaching peak bone mass, as well as the presence of certain disorders. Bone mass formation has been studied at various stages of development, from pregnancy, childhood, adolescence, and adulthood, where the greatest increase occurs to achieve peak bone mass. The increase in bone mass begins during the gestation process as a period of high fetal calcium demand and continues from birth through childhood and infancy, experiencing its maximum growth during adolescence until reaching the peak of bone mass in adulthood, around 20-30 years of age. Approximately 70% of bone mass is inherited from parents, while the remaining percentage is acquired through the processes of gestation, development, and growth, where environmental factors, nutrition, exercise, avoidance of toxic substances, and maintaining overall health contribute to achieving the highest concentration of bone mass. This becomes a reserve to respond to bone loss that typically starts around the age of 40, with the greatest loss during the transition to menopause and later, at a slower rate, during old age.

A Decrease in Maternal Iron Levels Is the Predominant Factor Suppressing Hepcidin during Pregnancy in Mice.

In order to supply adequate iron during pregnancy, the levels of the iron regulatory hormone hepcidin in the maternal circulation are suppressed, thereby increasing dietary iron absorption and storage iron release. Whether this decrease in maternal hepcidin is caused by changes in factors known to regulate hepcidin expression, or by other unidentified pregnancy factors, is not known. To investigate this, we examined iron parameters during pregnancy in mice. We observed that hepatic iron stores and transferrin saturation, both established regulators of hepcidin production, were decreased in mid and late pregnancy in normal and iron loaded dams, indicating an increase in iron utilization. This can be explained by a significant increase in maternal erythropoiesis, a known suppressor of hepcidin production, by mid-pregnancy, as indicated by an elevation in circulating erythropoietin and an increase in spleen size and splenic iron uptake. Iron utilization increased further in late pregnancy due to elevated fetal iron demand. By increasing maternal iron levels in late gestation, we were able to stimulate the expression of the gene encoding hepcidin, suggesting that the iron status of the mother is the predominant factor influencing hepcidin levels during pregnancy. Our data indicate that pregnancy-induced hepcidin suppression likely occurs because of reductions in maternal iron reserves due to increased iron requirements, which predominantly reflect stimulated erythropoiesis in mid-gestation and increased fetal iron requirements in late gestation, and that there is no need to invoke other factors, including novel pregnancy factor(s), to explain these changes.

Characterization of placentome vascular perfusion in relation to pregnancy associated glycoproteins throughout gestation in pregnant beef heifers

During pregnancy, blood flow to the uterus and placenta changes to support fetal demand. The placentomes serve as vascular attachment sites for exchange of gases, nutrients and fetal metabolic products. In human and veterinary medicine, non-invasive methods of ultrasonography and biomarkers have been described to assess placental health and fetal viability. Pregnancy associated glycoproteins (PAGs) are produced by the ruminant placenta and detected in maternal circulation. Current literature suggests that changes in circulating PAG con­centrations may be a useful biomarker for assessing placental health. The objective of this study is to determine the associa­tion between placentome blood perfusion and circulating PAG concentrations as they relate to the health of the developing fetal calf. The hypothesis states that placentome perfusion and PAG concentration will be positively correlated and associated with neonatal outcome.

Reticulocyte haemoglobin equivalent (ret-he) as a marker of bioavailability of iron in pregnant female- a study of 75 cases in a tertiary care centre

Abstract Background: Anaemia is the most frequent derailment of physiology in the world throughout the life of a woman. Women in the gestational period have a higher risk of presenting with iron-deficiency anaemia. The anaemia may occur due to inadequate intake of dietary iron, greater foetal demand and haemodilution, a physiological anaemia common in pregnant women in which changes in the maternal organism, such as changes in blood volume and factors associated with haemostasis, decrease haemoglobin concentration. The aim of study is to utilize Ret-He as a marker of bioavailability of iron in pregnant female. Material and Methods: This was a retrospective and prospective study carried out for a duration of 1 years and included total of 75 cases referred to Pathology Department, M. P. Shah Govt. Medical College and Guru Gobind Singh Hospital, Jamnagar- Gujarat. Clinical history, RET-He and other important parameters as well as findings of all the concerned pregnant females were collected. Results:Age of pregnant females varied from 19 years to 42 years. Mean age being 25.2 years. The reference ranges of RET-Hewas between 32.1 and 38.8 pg with a median of 34.17 pg. Hb and/or ferritin level were low in 3 pregnant women in 1st trimester with anaemia, 7 in 2nd and in 16 patients in 3rd trimester. Conclusions: Early diagnosis of iron deficiency anaemia in pregnancy is essential to prevent damage to both maternal and foetal health. In this study, we showed that the RET-He presents an excellent supplementary tool for the diagnosis of iron deficiency in pregnant women. Keywords: Anaemia, Iron deficiency, Pregnancy diagnosis, Reticulocytes, RET-He.

Effect of energy nutrition in the last third of gestation in beef cows on the productive and reproductive performance of their progeny

The present thesis evaluated the impact of restrictive and non-restrictive energy nutrition in beef cows in the last third of gestation on the productive and reproductive performance of the progeny. In addition, the effect of consumption of low-energy diets in pregnant cows in the last third of gestation on their own productive and reproductive variables was considered. Thirty-one multiparous, fixed-time inseminated, gestating British cows were assigned on day -90 (day 0 = calving) to two levels of energy intake relative to maintenance requirements until calving: i- 125 % (ALTO; n = 15) and ii- 75 % (BAJO; n = 16). At calving, energy-restricted cows had higher concentration of non-esterified fatty acids (AGNE) (P &lt; 0.01) and lower insulin concentration (P &lt; 0.03) relative to unrestricted cows. During lactation, restricted cows had lower body condition (P &lt; 0.05) and lower AGNE concentration (P = 0.05) with respect to non-restricted cows. Milk production was not significantly affected (P &gt; 0.05) by energy restriction. Regarding the characteristics evaluated in placentas, they were not affected by the treatments. Live weight (BW), morphometry and calf behaviour at birth were not significantly affected by the treatments. In contrast, energy restriction of cows affected PV at weaning (P &lt; 0.05) and daily liveweight gain (GD) at weaning (P &lt; 0.05) of (F1). From weaning to puberty, the GD and PV of the (F1) was not affected by the treatments. Similarly, the variables of (F2) were not affected by the treatments. In the present study, the undernourished cows mobilized body reserves and maintained milk production. Energy-restricted cows mobilized pre- and postpartum body reserves sufficient to supply fetal and milk production demands. Possibly, breeding cows grazing native range may develop similar resilient mechanisms, at least for the conditions of the present work. Specifically, there was no evident effect on calf growth and development parameters.

Organic Aciduria Disorders in Pregnancy: An Overview of Metabolic Considerations.

Organic acidurias are a heterogeneous group of rare inherited metabolic disorders (IMDs) caused by a deficiency of an enzyme or a transport protein involved in the intermediary metabolic pathways. These enzymatic defects lead to an accumulation of organic acids in different tissues and their subsequent excretion in urine. Organic acidurias include maple syrup urine disease, propionic aciduria, methylmalonic aciduria, isovaleric aciduria, and glutaric aciduria type 1. Clinical features vary between different organic acid disorders and may present with severe complications. An increasing number of women with rare IMDs are reporting successful pregnancy outcomes. Normal pregnancy causes profound anatomical, biochemical and physiological changes. Significant changes in metabolism and nutritional requirements take place during different stages of pregnancy in IMDs. Foetal demands increase with the progression of pregnancy, representing a challenging biological stressor in patients with organic acidurias as well as catabolic states post-delivery. In this work, we present an overview of metabolic considerations for pregnancy in patients with organic acidurias.

Pregnancy after Bariatric Surgery: Nutrition Recommendations and Glucose Homeostasis: A Point of View on Unresolved Questions.

Obesity is increasing in all age groups and, consequently, its incidence has also risen in women of childbearing age. In Europe, the prevalence of maternal obesity varies from 7 to 25%. Maternal obesity is associated with short- and long-term adverse outcomes for both mother and child, and it is necessary to reduce weight before gestation to improve maternal and fetal outcomes. Bariatric surgery is an important treatment option for people with severe obesity. The number of surgeries performed is increasing worldwide, even in women of reproductive age, because improving fertility is a motivating factor. Nutritional intake after bariatric surgery is dependent on type of surgery, presence of symptoms, such as pain and nausea, and complications. There is also a risk of malnutrition after bariatric surgery. In particular, during pregnancy following bariatric surgery, there is a risk of protein and calorie malnutrition and micronutrient deficiencies due to increased maternal and fetal demand and possibly due to reduction of food intake (nausea, vomiting). As such, it is necessary to monitor and manage nutrition in pregnancy following bariatric surgery with a multidisciplinary team to avoid any deficiencies in each trimester and to ensure the well-being of the mother and fetus.

Cyanotic Congenital Heart Disease in Pregnancy: A Review of Pathophysiology and Management.

The advancement of medical treatment and surgical technique, along with the invention of cardiopulmonary bypass, has allowed for long-term survival of patients with cyanotic congenital heart disease (CHD)-with many women with CHD now reaching child-bearing age and wishing to become pregnant. Pregnancy in these women is a major concern as the physiologic adaptations of pregnancy, including an increased circulating volume, increased cardiac output, reduced systemic vascular resistance, and decreased blood pressure, place a substantial load on the cardiovascular system. These changes are essential to meet the increased maternal and fetal metabolic demands and allow for sufficient placental circulation during gestation. However, in women with underlying structural heart conditions, they place an additional hemodynamic burden on the maternal body. Overall, with appropriate risk stratification, pre-conception counseling, and management by specialized cardiologists and high-risk obstetricians, most women with surgically corrected CHDs are expected to carry healthy pregnancies to term with optimization of both maternal and fetal risks. In this article, we describe the current understanding of 5 cyanotic CHDs-Tetralogy of Fallot, Transposition of the Great Arteries, Truncus Arteriosus, Ebstein's Anomaly, and Eisenmenger Syndrome-and explore the specific hemodynamic consequences, maternal and fetal risks, current guidelines, and outcomes of pregnancy in women with these conditions.

Late gestational nutrient restriction in primiparous beef females: nutrient partitioning among the dam, fetus, and colostrum during gestation.

Fall-calving primiparous crossbred beef females [body weight (BW): 451 ± 28 (SD) kg; body condition score (BCS): 5.4 ± 0.7] were allocated by fetal sex and expected calving date to receive either 100% (control; CON; n = 13) or 70% (nutrient restricted; NR; n = 13) of metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to calving. Heifers were individually-fed chopped poor quality hay and supplemented to meet targeted nutritional planes based on estimated hay intakes. Dam BW, BCS, backfat, and metabolic status were determined pre-treatment, every 21 d (BW and metabolic status) or 42 d (BCS and backfat) during gestation, and post-calving. At birth, calf BW and size were measured, and total colostrum from the most full rear quarter was collected pre-suckling. Data were analyzed with nutritional plane, treatment initiation date, and calf sex (when P < 0.25) as fixed effects. Gestational metabolites included day and nutritional plane × day as repeated measures. During late gestation, CON dams gained (P < 0.01) maternal (non-gravid) BW and maintained (P ≥ 0.17) BCS and backfat, while NR dams lost (P < 0.01) maternal BW, BCS, and backfat. Circulating glucose, urea N, and triglycerides were less (P ≤ 0.05) in NR dams than CON at most late gestational timepoints after treatment initiation. Circulating non-esterified fatty acids were greater (P < 0.01) in NR dams than CON. Post-calving, NR dams weighed 63.6 kg less (P < 0.01) and were 2.0 BCS less (P < 0.01) than CON. At 1 h post-calving, NR dams had less (P = 0.01) plasma glucose and tended to have less (P = 0.08) plasma triglycerides than CON. Nutrient restriction did not affect (P ≥ 0.27) gestation length, calf birth weight, or calf size at birth. Colostrum yield was 40% less (P = 0.04) in NR dams than CON. Protein and immunoglobulin concentrations were greater (P ≤ 0.04), but free glucose and urea N concentrations were less (P ≤ 0.03), in colostrum of NR dams than CON. Colostrum total lactose, free glucose, and urea N were less (P ≤ 0.03) in NR dams than CON, but total protein, triglycerides, and immunoglobulins were not affected (P ≥ 0.55). In summary, beef heifers experiencing late gestational nutrient restriction prioritized partitioning nutrients to fetal growth and colostrum production over maternal growth. During undernutrition, fetal and colostral nutrient demands were largely compensated for by catabolism of maternal tissue stores.

Challenges in Thyroid Function Testing: Interferences and Clinical Implications

In recent decades, significant advancements have been made in the methodologies used for evaluating thyroid dysfunctions. These advancements include the development of radioimmunoassays, immunometric assays, and liquid chromatography coupled with mass spectrometry. The main thyroid function tests include thyroid-stimulating hormone (TSH) and the measurement of triiodothyronine (T3) and thyroxine (T4), including their total and free fractions. Over time, different generations of TSH tests have been developed, starting from radioimmunoassays to immunometric assays, and more recently, tests utilizing fluorophores and chemiluminescent molecules. The third-generation tests are currently the most widely used due to their high sensitivity and specificity. Thyroid-stimulating hormone is preferred as the initial test for evaluating thyroid function since it has a log-linear relationship with free T4 levels, enabling the identification of subclinical hypothyroidism and subclinical hyperthyroidism. The reference range for normal TSH levels is typically between 0.45 and 4.5 mIU/L. However, there can be variations in TSH levels based on factors such as sex, age, and ethnicity. Specific reference values may be required for certain populations, such as the elderly, pregnancy, and neonates. In the elderly, an increase in TSH levels is expected. In the neonatal period, TSH levels are high after birth and take a few weeks to normalize. During pregnancy, various physiological changes occur, leading to alterations in thyroid hormones to meet fetal demands. Laboratory interferences in thyroid hormone assays must be considered to ensure accurate results. Biotin interference can lead to falsely low TSH and falsely high free T3 and T4 levels. Macro-thyrotropin can cause elevated TSH levels with normal thyroid hormone levels. Heterophilic antibodies can also cause false results. Additionally, the evaluation of autoantibodies and markers used in thyroid cancer follow-up needs special attention. Patients experiencing conditions like trauma, particularly in severe cases, may undergo changes in thyroid hormone levels, even without having a specific thyroid disease, which is called low triiodothyronine syndrome. In conclusion, it is essential to be aware of potential laboratory interferences and consider individual variations to ensure accurate interpretation and appropriate management of patients.

Serum sulfate level and Slc13a1 mRNA expression remain unaltered in a mouse model of moderate vitamin D deficiency.

Sulfate is essential for healthy foetal growth and neurodevelopment. The SLC13A1 sulfate transporter is primarily expressed in the kidney where it mediates sulfate reabsorption and maintains circulating sulfate levels. To meet foetal demands, maternal sulfate levels increase by twofold in pregnancy via upregulated SLC13A1 expression. Previous studies found hyposulfataemia and reduced renal Slc13a1 mRNA expression in rodent models with either severe vitamin D deficiency or perturbed vitamin D signalling. Here we investigated a mouse model of moderate vitamin D deficiency. However, serum sulfate level and renal Slc13a1 mRNA expression was not decreased by a moderate reduction in circulating vitamin D level. We confirmed that the mouse Slc13a1 5'-flanking region was upregulated by 1,25(OH)2D3 using luciferase assays in a cultured renal OK cell line. These results support the presence of a functional VDRE in the mouse Slc13a1 but suggests that moderate vitamin D deficiency does not impact on sulfate homeostasis. As sulfate biology is highly conserved between rodents and humans, we proposed that human SLC13A1 would be under similar transcriptional regulation by 1,25(OH)2D3. Using an online prediction tool we identified a putative VDRE in the SLC13A1 5'-flanking region but unlike the mouse Slc13a1 sequence, the human sequence did not confer a significant response to 1,25(OH)2D3 in vitro. Overall, this study suggests that moderate vitamin D deficiency may not alter sulfate homeostasis. This needs to be confirmed in humans, particularly during pregnancy when vitamin D and sulfate levels need to be maintained at high levels for healthy maternal and child outcomes.

Fetal growth patterns as early markers of fetal programming

The Barker hypothesis1 postulates that some organs and functions undergo programming during fetal life, setting in motion adaptative responses with delayed effects into adulthood. Although there is mounting evidence on the association between fetal exposure to some insults and permanent changes in postnatal life, the underlying mechanisms are not well understood, but could include epigenetic mechanisms involving gene imprinting. Imprinted genes have a role in placental development, regulating fetal demand, and the placental supply of maternal nutrients.