Metabolism is the fundamental process that sustains life. The heart, in particular, is an organ of high energy demand, and its energy substrates have been studied for more than a century. In recent years, there has been a growing interest in understanding the role of metabolism in the early differentiation of pluripotent stem cells and in cancer research. Studies have revealed that metabolic intermediates from glycolysis and the tricarboxylic acid cycle act as co-factors for intracellular signal transduction, playing crucial roles in regulating cell behaviors. Mitochondria, as the central hub of metabolism, are also under intensive investigation regarding the regulation of their dynamics. The metabolic environment of the fetus is intricately linked to the maternal metabolic status, and the impact of the mother\'s nutrition and metabolic health on fetal development is significant. For instance, it is well known that maternal diabetes increases the risk of cardiac and nervous system malformations in the fetus. Another notable example is the decrease in the risk of neural tube defects when pregnant women are supplemented with folic acid. These examples highlight the profound influence of the maternal metabolic environment on the fetal organ development program. Therefore, gaining insights into the metabolic environment within developing fetal organs is critical for deepening our understanding of normal organ development. This review aims to summarize recent findings that build upon the historical recognition of the environmental and metabolic factors involved in the developing embryo.

BACKGROUND: Craniofacial microsomia (CM) is characterized by changes in the first and second branchial arches. It is a clinical condition whose etiology is still uncertain, but studies have shown that genetic, nutritional, and environmental factors can result in disorders of blastogenesis of the branchial arches. This study evaluates gestational aspects, focusing on possible risk factors associated with CM.
METHODS: This is a case-control study conducted with patients monitored at a medical genetics service and compared to a control group of patients without evidence of malformations, born in a mother and child hospital, both located in Porto Alegre, Southern Brazil. Mothers\' data were obtained using questionnaires and by reviewing medical records. The sample consisted of 43 patients with CM (cases) and 129 patients without evidence of malformations (controls), paired by sex, totaling three controls for each case. Data analysis was performed using the two-tailed Fisher\'s exact test, Pearson\'s chi-square test, and the t-test.
RESULTS: We identified several factors associated with the development of CM, including the use of abortion methods by the mothers of these babies (p = .001), maternal diabetes (p = .009), advanced maternal age (p = .035), and a history of vaginal bleeding (p < .001). Furthermore, these patients exhibited a tendency to be born prematurely (p = .027), with low birth weight (p = .007), and lower Apgar scores (p = .003) when compared to healthy infants. Using a multivariate model, the use of abortion methods (p = .003) and vaginal bleeding (p = .032) remained independently associated with craniofacial microsomia.
CONCLUSIONS: We have identified several risk factors for the development of CM, including a propensity for premature birth, low birth weight, and respiratory difficulties. Additionally, women of advanced maternal age and/or those who used abortion methods and/or have diabetes have a higher risk of giving birth to a baby with CM. This information can be valuable in clinical practice, especially for the prevention of future cases.

Mounting evidence suggests metabolism instructs stem cell fate decisions. However, how fetal metabolism changes during development and how altered maternal metabolism shapes fetal metabolism remain unexplored. We present a descriptive atlas of in vivo fetal murine metabolism during mid-to-late gestation in normal and diabetic pregnancy. Using 13C-glucose and liquid chromatography-mass spectrometry (LC-MS), we profiled the metabolism of fetal brains, hearts, livers, and placentas harvested from pregnant dams between embryonic days (E)10.5 and 18.5. Our analysis revealed metabolic features specific to a hyperglycemic environment and signatures that may denote developmental transitions during euglycemic development. We observed sorbitol accumulation in fetal tissues and altered neurotransmitter levels in fetal brains isolated from hyperglycemic dams. Tracing 13C-glucose revealed disparate fetal nutrient sourcing depending on maternal glycemic states. Regardless of glycemic state, histidine-derived metabolites accumulated in late-stage fetal tissues. Our rich dataset presents a comprehensive overview of in vivo fetal tissue metabolism and alterations due to maternal hyperglycemia.

Intra-uterine growth restriction (IUGR) is a common cause of fetal/neonatal morbidity and mortality and is associated with increased offspring predisposition for cardiovascular disease (CVD) development. Mitochondria are essential organelles in maintaining cardiac function, and thus, fetal cardiac mitochondria could be responsive to the IUGR environment. In this study, we investigated whether in utero fetal cardiac mitochondrial programming can be detectable in an early stage of IUGR pregnancy. Using a well-established nonhuman IUGR primate model, we induced IUGR by reducing by 30% the maternal diet (MNR), both in males (MNR-M) and in female (MNR-F) fetuses. Fetal cardiac left ventricle (LV) tissue and blood were collected at 90 days of gestation (0.5 gestation, 0.5 G). Blood biochemical parameters were determined and heart LV mitochondrial biology assessed. MNR fetus biochemical blood parameters confirm an early fetal response to MNR. In addition, we show that in utero cardiac mitochondrial MNR adaptations are already detectable at this early stage, in a sex-divergent way. MNR induced alterations in the cardiac gene expression of oxidative phosphorylation (OXPHOS) subunits (mostly for complex-I, III, and ATP synthase), along with increased protein content for complex-I, -III, and -IV subunits only for MNR-M in comparison with male controls, highlight the fetal cardiac sex-divergent response to MNR. At this fetal stage, no major alterations were detected in mitochondrial DNA copy number nor markers for oxidative stress. This study shows that in 90-day nonhuman primate fetuses, a 30% decrease in maternal nutrition generated early in utero adaptations in fetal blood biochemical parameters and sex-specific alterations in cardiac left ventricle gene and protein expression profiles, affecting predominantly OXPHOS subunits. Since the OXPHOS system is determinant for energy production in mitochondria, our findings suggest that these early IUGR-induced mitochondrial adaptations play a role in offspring\'s mitochondrial dysfunction and can increase predisposition to CVD in a sex-specific way.

Trace minerals are essential nutrients that have many biologic functions, many of which are related to metabolic activities, immune function, and antioxidant capacity. The pregnant dam provides essential nutrients to support fetal development, including trace minerals. Milk is known to be an insufficient source of many trace minerals during the early nursing neonatal period. The fetal liver is capable of concentrating minerals to generate a reserve for use during postnatal life; however, the sufficiency of this reserve is dependent upon maternal mineral status. Appropriate mineral supplementation in the gestational diet is critical to supporting fetal development, maintaining adequate antioxidant capacity to survive the birthing process, and sustain immune function and growth of the newborn animal.

BACKGROUND: Abnormal fetal growth is associated with adverse perinatal and long-term outcomes. The pathophysiological mechanisms underlying these conditions are still to be clarified. Nerve growth factor (NGF) and neurotrophin-3 (NT-3) are two neurotrophins that are mainly involved in the neuroprotection process, namely promotion of growth and differentiation, maintenance, and survival of neurons. During pregnancy, they have been correlated with placental development and fetal growth. In this study, we aimed to determine the early 2nd trimester amniotic fluid levels of NGF and NT-3 and to investigate their association with fetal growth.
METHODS: This is a prospective observational study. A total of 51 amniotic fluid samples were collected from women undergoing amniocentesis early in the second trimester and were stored at -80 °C. Pregnancies were followed up until delivery and birth weight was recorded. Based on birth weight, the amniotic fluid samples were divided into three groups: appropriate for gestational age (AGA), small for gestational age (SGA), and large for gestational age (LGA). NGF and NT-3 levels were determined by using Elisa kits.
RESULTS: NGF concentrations were similar between the studied groups; median values were 10.15 pg/mL, 10.15 pg/mL, and 9.14 pg/mL in SGA, LGA, and AGA fetuses, respectively. Regarding NT-3, a trend was observed towards increased NT-3 levels as fetal growth velocity decreased; median concentrations were 11.87 pg/mL, 15.9 pg/mL, and 23.5 pg/mL in SGA, AGA, and LGA fetuses, respectively, although the differences among the three groups were not statistically significant.
CONCLUSIONS: Our findings suggest that fetal growth disturbances do not induce increased or decreased production of NGF and NT-3 in early second trimester amniotic fluid. The trend observed towards increased NT-3 levels as fetal growth velocity decreased shows that there may be a compensatory mechanism in place that operates in conjunction with the brain-sparing effect. Further associations between these two neurotrophins and fetal growth disturbances are discussed.

BACKGROUND: Fetal growth disturbances place fetuses at increased risk for perinatal morbidity and mortality. As yet, little is known about the basic pathogenetic mechanisms underlying deranged fetal growth. Apelin is an adipokine with several biological activities. Over the past decade, it has been investigated for its possible role in fetal growth restriction. Most studies have examined apelin concentrations in maternal serum and amniotic fluid in the third trimester or during neonatal life. In this study, apelin concentrations were examined for the first time in early second-trimester fetuses. Another major regulator of tissue growth and metabolism is insulin.
METHODS: This was a prospective observational cohort study. We measured apelin and insulin concentrations in the amniotic fluid of 80 pregnant women who underwent amniocentesis in the early second trimester. Amniotic fluid samples were stored in appropriate conditions until delivery. The study groups were then defined, i.e., gestations with different fetal growth patterns (SGA, AGA, and LGA). Measurements were made using ELISA kits.
RESULTS: Apelin and insulin levels were measured in all 80 samples. The analysis revealed statistically significant differences in apelin concentrations among groups (p = 0.007). Apelin concentrations in large for gestational age (LGA) fetuses were significantly lower compared to those in AGA and SGA fetuses. Insulin concentrations did not differ significantly among groups.
CONCLUSIONS: A clear trend towards decreasing apelin concentrations as birthweight progressively increased was identified. Amniotic fluid apelin concentrations in the early second trimester may be useful as a predictive factor for determining the risk of a fetus being born LGA. Future studies are expected/needed to corroborate the present findings and should ideally focus on the potential interplay of apelin with other known intrauterine metabolic factors.

Gestational Diabetes Mellitus (GDM) carries an increased risk for adverse perinatal and longer-term cardiometabolic consequences in offspring. This study evaluated the utility of maternal anthropometric, metabolic and fetal (cord blood) parameters to predict offspring anthropometry up to 1 year in pregnancies with GDM.
In this prospective analysis of the MySweetheart study, we included 193/211 women with GDM that were followed up to 1 year postpartum. Maternal predictors included anthropometric (pre-pregnancy BMI, gestational weight gain (GWG), weight and fat mass at the 1st GDM visit), and metabolic parameters (fasting insulin and glucose, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), Quantitative insulin-sensitivity check index (QUICKI), HbA1c, triglycerides, and high-density lipoprotein (HDL) at the 1st visit and HbA1c at the end of pregnancy). Fetal predictors (N=46) comprised cord blood glucose and insulin, C-Peptide, HOMA-IR, triglycerides and HDL. Offspring outcomes were anthropometry at birth (weight/weight z-score, BMI, small and large for gestational age (SGA,LGA)), 6-8 weeks and 1 year (weight z-score, BMI/BMI z-score, and the sum of 4 skinfolds).
In multivariate analyses, birth anthropometry (weight, weight z-score, BMI and/or LGA), was positively associated with cord blood HDL and HbA1c at the 1st GDM visit, and negatively with maternal QUICKI and HDL at the 1st GDM visit (all p ≤ 0.045). At 6-8 weeks, offspring BMI was positively associated with GWG and cord blood insulin, whereas the sum of skinfolds was negatively associated with HDL at the 1st GDM visit (all p ≤0.023). At 1 year, weight z-score, BMI, BMI z-score, and/or the sum of skinfolds were positively associated with pre-pregnancy BMI, maternal weight, and fat mass at the 1st GDM visit and 3rd trimester HbA1c (all p ≤ 0.043). BMI z-score and/or the sum of skinfolds were negatively associated with cord blood C-peptide, insulin and HOMA-IR (all p ≤0.041).
Maternal anthropometric, metabolic, and fetal metabolic parameters independently affected offspring anthropometry during the 1st year of life in an age-dependent manner. These results show the complexity of pathophysiological mechanism for the developing offspring and could represent a base for future personalized follow-up of women with GDM and their offspring.

Higher maternal body mass index (BMI) and abnormal glucose metabolism during early pregnancy are associated with congenital heart defects in the offspring, but the exact mechanisms are unknown.
We evaluated the association between maternal first trimester metabolic profile and transposition of the great arteries (TGA) in the offspring in a matched case-control study with 100 TGA mothers and 200 controls born in Finland during 2004-2014. Cases and controls were matched by birth year, child sex, and maternal age and BMI. Serum samples collected between 10- and 14-weeks of gestation were analyzed for 73 metabolic measures. Conditional logistic regression was used to assess the risk for TGA in the offspring, and a subgroup analysis among mothers with high BMI was conducted.
Higher concentrations of four subtypes of extremely large very-low-density lipoprotein (VLDL) particles and one of large VLDL particles were observed in TGA mothers. This finding did not reach statistical significance after multiple testing correction. The pooled odds ratio (OR) of the all metabolic variables was slightly higher in TGA mothers in the subgroup with maternal BMI over 25 (OR 1.25) and significantly higher in the subgroup with maternal BMI over 30 (OR 1.95) compared to the original population (OR 1.18).
Our findings indicate that an abnormal maternal early pregnancy metabolic profile might be associated with TGA in the offspring, especially in obese mothers. A trend indicating altered VLDL subtype composition in TGA pregnancies warrants further research.

Fetal exposure in adverse environmental factors during intrauterine life can lead to various biological adjustments, affecting not only in utero development of the conceptus, but also its later metabolic and endocrine wellbeing. During human gestation, maternal bone turnover increases, as reflected by molecules involved in bone metabolism, such as vitamin D, osteocalcin, sclerostin, sRANKL, and osteoprotegerin; however, recent studies support their emerging role in endocrine functions and glucose homeostasis regulation. Herein, we sought to systematically review current knowledge on the effects of aforementioned maternal bone biomarkers during pregnancy on fetal intrauterine growth and metabolism, neonatal anthropometric measures at birth, as well as on future endocrine and metabolic wellbeing of the offspring. A growing body of literature converges on the view that maternal bone turnover is likely implicated in fetal growth, and at least to some extent, in neonatal and childhood body composition and metabolic wellbeing. Maternal sclerostin and sRANKL are positively linked with fetal abdominal circumference and subcutaneous fat deposition, contributing to greater birthweights. Vitamin D deficiency correlates with lower birthweights, while research is still needed on intrauterine fetal metabolism, as well as on vitamin D dosing supplementation during pregnancy, to diminish the risks of low birthweight or SGA neonates in high-risk populations.