[Antenatal exposure to corticosteroids for fetal lung maturation and its repercussion on weight, length and head circumference in the newborn infant]

Impact of corticosteroid exposure on preterm labor in neonates eventually born at term

OBJECTIVE

To evaluate the impact of antenatal corticosteroid therapy (ACS) on birth outcomes in term infants exposed during pregnancy.

STUDY DESIGN

Exposed newborns were compared with non-exposed controls in a 1 to 2 design. Multivariate analysis was used to assess the effect of ACS exposure on neonatal outcomes.

RESULT

408 newborns were included (136 exposed to ACS, 272 non-exposed). Mean ± SD head circumference (HC) was 33.7 ± 1.4 vs 34.3 ± 1.6 cm, p = 0.001 in exposed vs controls; birth weight was 3.1 ± 0.4 vs 3.3 ± 0.4 kg, p = 0.0001; and birth height was 47.9 ± 2.1 vs. 49.1 ± 2.0 cm, p < 0.0001. Hypocalcemia (4.4 vs 0.7%, p = 0.019) and feeding difficulties (5.1 vs 1.5%, p = 0.047) were significantly more common in exposed newborns. Multivariate analysis for HC showed a significant independent association with ACS exposure (β = -0.5, p = 0.009).

CONCLUSION

Term newborns exposed to ACS have lower birth HC and higher risk of neonatal complications.

CLINICAL TRIAL REGISTRATION

NCT05640596.

Antenatal dexamethasone retarded fetal long bones growth and development by down-regulating of insulin-like growth factor 1 signaling in fetal rats

OBJECTIVE

Dexamethasone (DEX), a synthetic glucocorticoid, has been widely used as a medication for premature delivery. However, the side effects of antenatal DEX treatment on fetal bone development, as well as the underlying mechanisms still remain to be elucidated. Here, we aimed to explore the effects and the related mechanisms of antenatal DEX exposure during late pregnancy on fetal bone growth and development.

METHODS

Pregnant Sprague-Dawley rats were randomly divided into DEX group and vehicle group from gestational day 14 (GD14). Pregnant rats in DEX group were intraperitoneally injected once with DEX (200 µg/kg body weight) on GD14, 16, 18, and 20. The vehicle group rats were administered the same amount of normal saline at the same time. Pregnant rats were anesthetized at GD21 to harvest fetal femurs for analysis.

RESULTS

Antenatal DEX treatment delayed fetal skeletal growth via inhibiting extracellular matrix (ECM) synthesis and downregulating insulin-like growth factor 1 (IGF1) signaling. Several components of IGF1 signaling pathway, including IGF1 receptor, insulin receptor substrate, as well as serine-threonine protein kinase, were down-regulated in fetal growth plate chondrocytes following DEX treatment.

CONCLUSION

This study indicated that antenatal DEX treatment-retarded fetal skeletal growth was associated with the down-regulation of IGF1 signaling in growth plate chondrocytes, providing important information about the impact of antenatal DEX application four courses on premature infant.

Antenatal glucocorticoid treatment affects hippocampal development in mice

Synthetic glucocorticoids are administered to pregnant women at risk for preterm delivery, to enhance fetal lung maturation. The benefit of this treatment is well established, however caution is necessary because of possible unwanted side effects on development of different organ systems, including the brain. Actions of glucocorticoids are mediated by corticosteroid receptors, which are highly expressed in the hippocampus, a brain structure involved in cognitive functions. Therefore, we analyzed the effects of a single antenatal dexamethasone treatment on the development of the mouse hippocampus. A clinically relevant dose of dexamethasone (0.4 mg/kg) was administered to pregnant mice at embryonic day 15.5 and the hippocampus was analyzed from embryonic day 16 until adulthood. We investigated the effects of dexamethasone treatment on anatomical changes, apoptosis and proliferation in the hippocampus, hippocampal volume and on total body weight. Our results show that dexamethasone treatment reduced body weight and hippocampal volume transiently during development, but these effects were no longer detected at adulthood. Dexamethasone treatment increased the number of apoptotic cells in the hippocampus until birth, but postnatally no effects of dexamethasone treatment on apoptosis were found. During the phase with increased apoptosis, dexamethasone treatment reduced the number of proliferating cells in the subgranular zone of the dentate gyrus. The number of proliferative cells was increased at postnatal day 5 and 10, but was decreased again at the adult stage. This latter long-term and negative effect of antenatal dexamethasone treatment on the number of proliferative cells in the hippocampus may have important implications for hippocampal network function.

Animal models for small for gestational age and fetal programming of adult disease

Fetal growth retardation is a fetal adaptation in response to inadequate supply of oxygen and/or nutrients. Animal models of intrauterine growth retardation are an invaluable tool to question the genetic, molecular and cellular events that determine fetal growth and development. Rodent and non-litter bearing animals are mammalian system with similar embryology,anatomy and physiology to humans. Utilization of these systems has led to a greater understanding of the pathophysiology and consequences of intrauterine growth retardation. These observations are comparable to that observed in humans born small for gestational age, and are of interest because of the known association between poor fetal growth and development of adult disease. All the experimental manipulations described here have altered a number of metabolic and physiological variables, but the pattern of alterations seems to vary with the procedure and species employed. This review describes animal models for intrauterine growth retardation and assesses their potentials and limitations at aiming to improve strategies for the prevention of adult disease.