The transition from fetus to neonate--an endocrine perspective

The transition from fetus to neonate involves three phases: late gestation, parturition and the processes needed to establish independent homoeostatic regulation after separation from the placenta. These phases are regulated by a series of fetal and placental endocrine events. Glucocorticoids have an important role in the preparation for birth, including involvement in lung and cardiac development, and the maturation of enzymes in a variety of pathways. Fetal cortisol production is, in turn, also under hormonal control. Parturition is a complex process, which is still poorly understood in humans. The final steps are largely dependent on the effect of prostaglandin F2 alpha on the myometrium associated with increased oxytocin activity. The transition to birth is accompanied by changes in respiration, circulation, glucose homoeostasis, and the onset of independent oral feeding and thermoregulation. Several examples of endocrine components of the transition from fetal to neonatal life are reviewed here: the role of prostanoids, the onset of thermogenesis, and changes in the thyroid hormone and growth hormone axes. The effects of hormone levels on prematurity and growth retardation are also discussed.     

Serial change in myocardial tissue Doppler imaging from fetus to neonate

Background

Our goal was to evaluate the serial change in myocardial performance from fetus to neonate using tissue Doppler imaging (TDI).

Method and results

There were 37 term infants in the present study. The TDI sensor was placed at the level of the lateral mitral annulus (M-TDI), inter-ventricular septum (IVS-TDI) and the lateral tricuspid annulus (T-TDI). We measured TDI parameters from fetus to neonate. On univariate analysis, E′ (cm/s), A′ (cm/s), and S′ (cm/s) of three ventricular walls of TDI parameters excluding E′ IVS-TDI significantly decreased during the transition from fetal to neonatal circulation. E′/A′ ratio, E/E′ ratio and myocardial performance index (MPI) of three ventricular walls of TDI parameters excluding T-TDI MPI significantly increased during the transition from fetal to neonatal circulation. When multiple linear regression analysis with a step-wise procedure during the transition from fetus to neonate for TDI parameters was applied to variables, significant differences were noted for predicting decreases in M-TDI S′ (6.55 to 3.97, p < 0.001) and IVS-TDI A′, (6.69 to 4.69, p < 0.001), and increases in IVS-TDI E′/A′ ratio (0.77 to 1.02, p < 0.001) and IVS-TDI E/E′ ratio (8.25 to 13.65, p < 0.001).

Conclusion

In conclusion, we found that the myocardial performances of both ventricles decreased during the transition from fetus to neonate using TDI parameters. In particular, left ventricular systolic performance was affected more than when fetal circulation changed to neonate circulation. Our findings suggest that serial change in TDI can give new information to estimate myocardial performance of the neonate.     

Resuscitation at the limits of viability – an Irish perspective

Background:  Advances in neonatal care continue to lower the limit of viability. Decision making in this grey zone remains a challenging process.
Objective:  To explore the opinions of healthcare providers on resuscitation and outcome in the less than 28-week preterm newborn.
Design/Methods:  An anonymous postal questionnaire was sent to health care providers working in maternity units in the Republic of Ireland. Questions related to neonatal management of the extreme preterm infant, and estimated survival and long-term outcome.
Results:  The response rate was 55% (74% obstetricians and 70% neonatologists). Less than 1% would advocate resuscitation at 22 weeks, 10% of health care providers advocate resuscitation at 23 weeks gestation, 80% of all health care providers would resuscitate at 24 weeks gestation. 20% of all health care providers would advocate cessation of resuscitation efforts on 22–25 weeks gestation at 5 min of age. 65% of Neonatologists and 54% trainees in Paediatrics would cease resuscitation at 10 min of age. Obstetricians were more pessimistic about survival and long term outcome in newborns delivered between 23 and 27 weeks when compared with neonatologists. This difference was also observed in trainees in paediatrics and obstetrics.
Conclusion:  Neonatologists, trainees in paediatrics and neonatal nurses are generally more optimistic about outcome than their counterparts in obstetrical care and this is reflected in a greater willingness to provide resuscitation efforts at the limits of viability.     

Consequences for fetus and neonate of maternal red cell allo-immunisation

AIMS—To study the distribution of clinically important red cell antibodies in pregnancy, and the associated fetal and neonatal morbidity and mortality.
METHODS—The case notes of women with clinically important red cell antibodies identified in their serum during pregnancy were reviewed.
RESULTS—During a 12 month period 22 264 women were referred for antenatal screening. Clinically important red cell antibodies were detected in 244 (1%). Of these, 100 were anti-D and 144 were non-RhD antibodies. There were three intrauterine deaths, three fetuses required intrauterine transfusion, 10 neonates were transfused, 27 others had phototherapy, and 27 with a positive direct antiglobulin test received no treatment. Early fetal losses occurred in the presence of both high and low levels of anti-D.
CONCLUSIONS—Anti-D remains the most common clinically important antibody in pregnancy, and accounts for the greatest fetal and neonatal morbidity and mortality. Of the other antibodies detected, anti-c was associated with most neonatal morbidity. The production of many of the non-D antibodies detected could be avoided by the use of selected red cells when transfusing pre-menopausal women.

     

The neonate with an abdominal mass

Abdominal masses in neonates reflect a wide spectrum of diseases,from lesions that can cause significant morbidity and mortality,to conditions readily corrected surgically, to entities which maybe safely observed. It is incumbent upon the infant's physician to determine the nature of the mass in a timely, safe, and cost-effective manner.     

从胎儿到新生儿的过渡

胎儿从宫内的“寄生”生活,到子宫外的独立生活的过渡发生在娩出过程及出生后数天内。这种过渡是决定新生儿生命质量的重要过程,在分娩室的急救中除了先天性异常外,绝大部分与这种过渡中发生的意外有关。因此了解生命中这一关键时段的病理生理基础,是十分重要的。1　妊娠期胎儿与孕母的依存1 1　母体对胎儿的接纳　胎儿的遗传物质有一半来自父亲,因此胎儿对于孕妇来说是半个异体同种移植物,妊娠是母体对胎儿的接纳与容受过程。从受精开始发生了一系列的生理改变,涉及各系统,特别是免疫系统,产生对胎儿抗原的免疫抑制,使胎儿不被排斥,得以在…     

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目的了解不同年龄小儿胃酸度变化的特点。方法用便携式pH动态监测仪(Medtronic)对982例不同年龄儿童进行空腹胃pH值测定。结果空腹胃pH值在新生儿期(128例)、~1岁组(288例)、~3岁组(182例)、~7岁组(210例)、~15岁组(174例)分别为2·32±0·90、1·92±0·58、1·66±0·63、1·70±0·48、1·59±0·47。2周不到的新生儿(77例)与大于2周的新生儿(51例)空腹胃pH值分别为2·30±0·92、2·35±0·88,其差异无统计学意义。新生儿组与各组间的差异有统计学意义(P均<0·001);~1岁组与各组间的差异也有统计学意义(P均<0·001)。,而~3岁组、~7岁组和~15岁组之间的差异则无统计学意义(P>0·05)。结论新生儿期胃内已呈酸性环境,但其胃pH值高于婴幼儿及年长儿;随着年龄的增长,胃pH值逐渐降低,1岁以后已接近成人水平;提示酸相关性疾病可发生于包括新生儿在内的儿童。     

Lactogenesis. The transition from pregnancy to lactation

The most important factors in initiation of the cascade of changes in the mammary epithelium that constitute lactogenesis stage II seem to be a prepared mammary epithelium, progesterone withdrawal, maintained plasma prolactin (in most species), and removal of milk from the breast within an undefined interval after birth. Although the molecular mechanisms by which prolactin regulates milk protein synthesis are the subject of intense and productive studies, the specific mechanisms by which progesterone and milk removal interact with the mammary epithelial cell at parturition have not been studied, perhaps because no in vitro model system exists that mimics lactogenesis stage II, or because of the complexity of the changes that must be coordinated during this process, or because of a lack of general understanding of the complex progression of changes in the function of the breast as it goes from the quiescent state of pregnancy to the active secretory state of lactation. With new technologies designed to investigate the biology of complex systems arising from the growing knowledge of the genome of human and animal species and the growing availability of animal and tissue culture models for these processes, physicians can expect a rapid increase in the molecular understanding of lactogenesis in the near future. These fundamental studies must be coupled with good prospective clinical studies if physicians are to obtain a useful, comprehensive understanding of lactogenesis in women.     

Changes in plasma arginine vasopressin during transition from fetus to newborn following minimal trauma delivery of lambs and goats

Vasopressin in umbilical arterial and venous blood is high at delivery and may be important in the maintenance of arterial pressure and absorption of lung liquid. We used chronically instrumented near-term fetal lambs and goats to investigate the changes in plasma vasopressin that occur during perinatal cardiovascular transition following cesarean section without labor. Plasma arginine vasopressin was more than 5 times greater 15 min following birth than immediately prior to clamping the umbilicus, and it fell progressively over the ensuing 2-5 h to levels not significantly different from before birth. Fifteen min after delivery, neither arterial pressure, blood gases, nor pH appeared to account for the increase.     

The needs of looked after children from an adverse childhood experience perspective

There has been considerable interest in the association of Adverse Childhood Experiences (ACEs) and health and social care outcomes in adulthood. One way of thinking about the needs of looked after children is through an Adverse Childhood Experiences lens as looked after children have commonly been exposed to very high rates of ACEs. This paper makes the case that the association between exposure to ACEs and poor adult outcomes in the general population is heightened in looked after children and care leavers who have the same outcomes as the general population, but more often and at an earlier age.     

Hormone ontogeny in the ovine fetus: XIX: The effect of a potent luteinizing hormone-releasing factor agonist on gonadotropin and testosterone release in the fetus and neonate

To investigate further the role of the hypothalamic luteinizing hormone releasing factor (LRF) pulse generator and the pituitary LRF receptor in the regulation of gonadotropin secretion and gonadal steroidogenesis in the ovine (O) fetus and neonatal lamb, we measured the increment (the difference between the concentration of plasma LH at time 0 and peak LH) in oLH (delta oLH) and oFSH (delta oFSH) responses to a potent LRF agonist, D-Trp6Pro9NEt-LRF (LRF-A), after consecutive daily doses in 17 ovine fetuses (six females, 11 males) and in 15 neonatal lambs (six females, nine males). Seven of the lambs had been studied as fetuses. In addition, plasma concentrations of testosterone (T) and androstenedione (delta 4A) were measured in nine male fetuses. After a stimulatory response to the first dose of LRF-A, the mean delta oLH and delta oFSH responses in the 106- to 118-d gestation fetuses of both sexes were significantly suppressed by the fourth dose and in the neonatal lamb by the second dose. Suppression was sustained throughout the duration of LRF-A therapy which included the gestational interval when the fetal pituitary exhibits its greatest responsiveness to an acute dose of synthetic LRF. The duration of oLH and oFSH suppression after cessation of LRF-A therapy was studied by measuring the delta oLH and delta oFSH responses to LRF before and at intervals after LRF-A therapy. In the fetus, the delta oLH and delta oFSH responses remained significantly decreased 7-8 d after the agonist was discontinued.(ABSTRACT TRUNCATED AT 250 WORDS)