Sex-specific associations of insulin-like peptides in cord blood with size at birth

Placentae of small appropriately-grown-for-gestational-age neonates exhibit sexually dimorphic transcriptomic changes representative of placental insufficiency

INTRODUCTION

Previous studies have reported that neonates less than the 25th BWC especially if they were male, were more likely to be associated with birth complications suggesting small neonates often identified as appropriately grown are at risk of adverse outcomes. We have questioned whether smaller neonates not typically categorized as "small for gestational age" may not reach their genetically determined growth due to placental insufficiency.

METHODS

RNA-Seq was performed on the Illumina NovaSeq 600 using term placentae from neonates that were less than the 10th birthweight centile (BWC) (n = 39), between the 10th and the 30th BWC (n = 15) or greater than the 30th BWC (n = 23). Bioinformatic analyses were conducted and statistical significance was assessed at a level of P < 0.05 for single comparisons or FDR <0.05 unless otherwise noted.

RESULTS

Gene set enrichment analysis revealed differences between BWC groups and in relation to the sex of the placenta. Genes associated with hypoxia, inflammatory responses, estrogen responsive genes, and androgen responsive genes were enriched (FDR <0.1) for in placentae of neonates <10th BWC regardless of sex and also in male placentae of neonates between the 10th-30th BWC. Female placenta of neonates between the 10th-30th BWC were comparable to placentae of neonates >30th BWC.

DISCUSSION

These findings provide evidence that small male neonates may be at a greater risk of an adverse outcome than females due to changes in gene expression that are associated with placental dysfunction. The current data raises questions of whether placental pathology for smaller appropriately grown neonates should be scientifically and clinically examined in more depth.

Fetoplacental oxygen homeostasis in pregnancies with maternal diabetes mellitus and obesity

Despite improvements in clinical management, pregnancies complicated by pre-existing diabetes mellitus, gestational diabetes mellitus or obesity carry substantial risks for parent and offspring. Some of the endocrine and metabolic changes in parent and fetus in diabetes mellitus and obesity lead to fetal oxygen deficit, mostly due to insulin-induced accelerated fetal metabolism. The human fetus deals with reduced oxygenation through a wide range of adaptive responses that act at various levels in the placenta as well as the fetus. These responses ensure adequate oxygen delivery to the fetus, increase the oxygen transport capacity of fetal blood and redistribute oxygen-rich blood to vital organs such as the brain and heart. The liver has a central role in adapting to reduced oxygenation by increasing its oxygen extraction and stimulating erythropoietin synthesis to increase haematocrit. The type of adaptive response depends on the onset and duration of hypoxia and the severity of the metabolic disturbance. In pregnancies characterized by diabetes mellitus or obesity, these adaptive systems come under additional strain owing to the increased maternal supply of glucose and resultant fetal hyperinsulinaemia, both of which stimulate oxidative metabolism. In the rare situation that the adaptive responses are overwhelmed, stillbirth can ensue.

The impact of fetal sex on risk factors for gestational diabetes and related adverse pregnancy outcomes

AIMS

To investigate whether fetal sex affects the impact of classical GDM risk factors on the diagnosis of gestational diabetes (GDM) as well as on related adverse pregnancy outcomes.

METHODS

This retrospective observational study concerned 206,917 singleton live births born to 170,126 women aged 15-45 over the years 2010-2018 in Tuscany, Italy. GDM was identified by administrative data-sources in 21,613 pregnancies (10.5%) by assessing, through multiple logistic models, whether fetal sex modified the risk of GDM driven by maternal risk factors, and whether it modified the risk of adverse outcomes such as prematurity (birth ≤ 37th gestational week), large for gestational age (LGA), unplanned caesarean sections, or 5-min-Apgar-index ≤ 7 in pregnancies with GDM.

RESULTS

GDM was diagnosed in 21,613 pregnancies (10.5%). Male fetal sex predicted a higher adjusted risk of GDM: OR = 1.05(95% CI: 1.01-1.07); p < 0.0009. In pregnancies with female sex, pre-pregnancy obesity amplified the risk of GDM: OR = 1.09(95% CI: 1.01-1.19); p =  0.04. In pregnancies with GDM, carrying a female fetus increased the risk of LGA associated with pregestational obesity OR = 1.45(95% CI: 1.15-1.81); p = 0.001, and in primiparous pregnancies, it protected mothers from the risk of unplanned caesarean sections OR = 0.80(95%CI: 0.67-0.92); p = 0.001.

CONCLUSIONS

While male fetal sex is associated with rise in the risk of GDM, giving birth to a girl amplifies the excess GDM risk driven by pregestational obesity, thus increasing the risk of LGA in pregnancies with GDM. Additionally, female fetal sex in pregnancies with GDM seems to protect from the risk of unplanned caesarean sections in primiparous pregnancies.

Predictors of neonatal adiposity and associations by fetal sex in women with gestational diabetes mellitus and normal glucose-tolerant women

AIMS

To determine predictors of neonatal adiposity and differences in associations by fetal sex in women with gestational diabetes mellitus (GDM), normal-weight and overweight (BMI ≥ 25 kg/m²) normal glucose-tolerant women (NGT).

METHODS

Skinfold thickness was measured in 576 newborns, and cord blood leptin, c-peptide and lipids in 327 newborns in a multi-centric prospective cohort study.

RESULTS

Compared to neonates of normal-weight NGT women (327), neonates of women with GDM (97) were more often large-for-gestational age (LGA) (16.5% vs 8.6%, p = 0.024) ,but the macrosomia rate (8.2% vs 5.8%, p = 0.388), sum of skinfolds (13.9 mm ± 2.9 vs 13.3 mm ± 2.6, p = 0.067), neonatal fat mass (1333.0 g ± 166.8 vs 1307.3 g ± 160.9, p = 0.356), and cord blood biomarkers were not significantly different. Compared to neonates of normal-weight NGT women, neonates of overweight NGT women (152) had higher rates of macrosomia (12.5% vs 5.8%, p = 0.012), LGA (17.1% vs 8.6%, p = 0.006), higher sum of skinfolds (14.3 mm ± 2.6 vs 13.2 mm ± 2.6, p < 0.001), neonatal fat mass (1386.0 g ± 168.6 vs 1307.3 g ± 160.9, p < 0.001), % neonatal fat mass > 90th percentile (15.2% vs 7.1%, p < 0.001), without significant differences in cord blood biomarkers. Maternal BMI, fasting glycemia, triglycerides, gestational weight gain, cord blood leptin ,and cord blood triglycerides were independent predictors for neonatal adiposity. Gestational weight gain was positively associated with adiposity in boys only.

CONCLUSION

Compared to neonates of normal-weight NGT women, neonates of GDM women have higher LGA rates but similar adiposity, while neonates of overweight NGT women have increased adiposity. Limiting gestational weight gain might be especially important in the male fetus to reduce neonatal adiposity.

Adipose tissue development and lipid metabolism in the human fetus: The 2020 perspective focusing on maternal diabetes and obesity

During development, the human fetus accrues the highest proportion of fat of all mammals. Precursors of fat lobules can be found at week 14 of pregnancy. Thereafter, they expand, filling with triacylglycerols during pregnancy. The resultant mature lipid-filled adipocytes emerge from a developmental programme of embryonic stem cells, which is regulated differently than adult adipogenesis. Fetal triacylglycerol synthesis uses glycerol and fatty acids derived predominantly from glycolysis and lipogenesis in liver and adipocytes. The fatty acid composition of fetal adipose tissue at the end of pregnancy shows a preponderance of palmitic acid, and differs from the mother. Maternal diabetes mellitus does not influence this fatty acid profile. Glucose oxidation is the main source of energy for the fetus, but mitochondrial fatty acid oxidation also contributes. Indirect evidence suggests the presence of lipoprotein lipase in fetal adipose tissue. Its activity may be increased under hyperinsulinemic conditions as in maternal diabetes mellitus and obesity, thereby contributing to increased triacylglycerol deposition found in the newborns of such pregnancies. Fetal lipolysis is low. Changes in the expression of genes controlling metabolism in fetal adipose tissue appear to contribute actively to the increased neonatal fat mass found in diabetes and obesity. Many of these processes are under endocrine regulation, principally by insulin, and show sex-differences. Novel fatty acid derived signals such as oxylipins are present in cord blood with as yet undiscovered function. Despite many decades of research on fetal lipid deposition and metabolism, many key questions await answers.

Sex differences in infant health following ART-treated, subfertile, and fertile deliveries

PURPOSE

Among infants following ART-treated, subfertile, and fertile deliveries to determine (1) the presence and magnitude of sex differences in health outcomes and (2) whether the presence of sex differences varied among maternal fertility groups.

METHODS

Retrospective cohort analysis of infants born in Massachusetts (MA) in 2004-2013 who were conceived by ART. The Society for Assisted Reproductive Technology Clinic Outcome Reporting System was linked to the Pregnancy to Early Life Longitudinal data system, which links birth certificates to hospital discharge records for MA mothers and infants. Included were singletons born via ART-treated, subfertile, and fertile deliveries. Multivariable logistic regression was used to model the association between infant sex and health outcomes, controlling for maternal demographic and health characteristics.

RESULTS

A total of 16,034 ART-treated, 13,277 subfertile, and 620,375 fertile singleton live births were included. For all three groups, males had greater odds of being preterm (AOR range 1.15-1.2), having birth defects (AOR range 1.31-1.71), experiencing respiratory (AOR range 1.33-1.35) and neurologic (AOR range 1.24-1.3) conditions, and prolonged hospital stay (AOR range 1.19-1.25) compared to females. The interaction between maternal fertility group and infant sex for all infant outcomes was nonsignificant, denoting that the presence of sex differences among fertile, subfertile, and ART groups did not vary.

CONCLUSION

Sex differences in birth outcomes of infants following ART-treated, subfertile, and fertile deliveries exist but the magnitude of these differences does not vary among these maternal fertility groups.

Gestational diabetes mellitus

Hyperglycaemia that develops during pregnancy and resolves after birth has been recognized for over 50 years, but uniform worldwide consensus is lacking about threshold hyperglycaemic levels that merit a diagnosis of 'gestational diabetes mellitus' (GDM) and thus treatment during pregnancy. GDM is currently the most common medical complication of pregnancy, and prevalence of undiagnosed hyperglycaemia and even overt diabetes in young women is increasing. Maternal overweight and obesity, later age at childbearing, previous history of GDM, family history of type 2 diabetes mellitus and ethnicity are major GDM risk factors. Diagnosis is usually performed using an oral glucose tolerance test (OGTT), although a non-fasting, glucose challenge test (GCT) is used in some parts of the world to screen women for those requiring a full OGTT. Dietary modification and increased physical activity are the primary treatments for GDM, but pharmacotherapy, usually insulin, is used when normoglycaemia is not achieved. Oral hypoglycaemic agents, principally metformin and glibenclamide (glyburide), are also used in some countries. Treatment improves immediate pregnancy outcomes, reducing excess fetal growth and adiposity and pregnancy-related hypertensive disorders. GDM increases the risk of long-term complications, including obesity, impaired glucose metabolism and cardiovascular disease, in both the mother and infant. Optimal management of mother and infant during long-term follow-up remains challenging, with very limited implementation of preventive strategies in most parts of the world.