Transepidermal water loss in infants born at 24 and 25 weeks of gestation

The rate of evaporation of water from the skin of 13 infants born at 24 (n = 3) and 25 (n     

Prostaglandin concentrations in ovine maternal and fetal tissues at late gestation

Maternal and fetal sheep organs were measured for their concentrations of prostaglandins (PG) E2, F2 alpha, 13,14-dihydro-15-keto PGF2 alpha (PGFM), 6-keto PGF1 alpha (hydrolysis produce of PGI2), and 6-keto PGE1 (enzymatic product of PGI2) by radioimmunoassay at day 131 of pregnancy (0.90 gestation). It was observed that the concentrations of PGFM were greater (p less than 0.01) in maternal endometrium than in any other maternal tissue or any other PG measured in endometrium. The lowest concentrations of PG in maternal tissues were in the myometrium, while PGE2 and 6-keto PGF1 alpha were present in maternal lungs in high concentrations. Fetal prostaglandin concentrations were high in the chorioallantois, fetal portion of the cotyledons and amnion, while they were very low in the kidney, liver, and lung. Fetal lung concentrations were lower than maternal lung concentrations (p less than 0.01) for all PG measured. In fetal aorta and ductus arteriosus, 6-keto PGF1 alpha concentrations were significantly greater (p less than 0.05) than all other measured PG, while in umbilical artery and vein 6-keto PGF1 alpha levels were equal to PGE2 levels. 6-Keto PGE1 concentrations were consistently among the lowest in all tissues measured. These results suggest that the endometrium may serve as a metabolic barrier to PG diffusing from the chorioallantois to the myometrium, that the capacity of pulmonary tissue to produce PG may increase with age, that the fetal membranes and cotyledons may be one major source of circulating PG in the fetus, and that 6-keto PGF1 alpha is the major metabolite of PGI2 in ovine tissues.     

The blood flow velocity waveform in the fetal descending aorta; its relationship to fetal heart rate pattern, eye and body movements in normal pregnancy at 27-28 weeks of gestation

In 13 normal pregnancies at 27-28 weeks of gestation the blood flow velocity waveform at the lower thoracic level of the fetal descending aorta was studied in relation to fetal heart rate pattern (FHRP), fetal eye movements (FEM) and fetal body movements (FBM). State parameter combinations in which high fetal heart rate (FHR) variability was present, were associated with a significant reduction in pulsatility index (PI) as compared with periods in which low FHR variability was present, irrespective of FEM and FBM, indicating a reduced peripheral vascular resistance. At 27-28 weeks of gestation FHR variability and PI might be linked to baroreceptor sensitivity. PI values derived from combinations FHRP-A, FEM(-), FBM(-) and FHRP-B, FEM(+), FBM(+) showed a significant inverse relationship (P less than 0.05) with FHR. FHR and FHR variability should be taken into account when studying flow velocity waveforms in the fetal descending aorta at 27-28 weeks of gestation.     

Mediators of behavioral problems in 7-year-old children born after 24 to 28 weeks of gestation

We tested the hypothesis that prematurity acts through its association with neuromotor and intellectual functioning to explain behavior problems at school age. Sixty-one extremely preterm (EP) very low birth weight (VLBW) children (< 29 wk and < 1,500 g) born in 1987-1990 and 44 normal birth weight children (NBW) (> 37 wk and > 2,500 g) were matched for age, sex, and socioeconomic status (SES). Mediator variables were evaluated at a hospital at 5 years and 9 months. Behaviors were evaluated at school at 7 years by peers, teachers, and parents. When compared with NBW children, EP/VLBW children had poorer IQ and neuromotor development. At school, EP/VLBW children were evaluated by peers as more sensitive/ isolated, and by teachers and parents as more inattentive and hyperactive than NBW. When mediators were introduced, the previously significant relation between prematurity and behavior problems disappeared. Hyperactive and inattentive behaviors were explained by a specific working memory factor for the latter, and by a general intellectual delay for the former, whereas sensitive/isolated behaviors were best explained by neuromotor delays. Inattentive behaviors were also related to family adversity. At school age, extreme prematurity had thus an indirect effect on behaviors via specific and nonspecific intellectual and neuromotor delays.     

36周胎龄人胎脑不同部位神经干细胞变化特征研究

目的观察同胎龄不同部位人胎脑神经干细胞(NSCs)的变化特征。方法收集胎龄36周的水囊引产胎儿15例,采用免疫组织化学技术对人胎脑海马、纹状体、室下区、额叶、颞叶、枕叶、顶叶等部位NSCs的分布、形态、生长方式以及数量进行检测。结果36周胎脑海马、纹状体、室下区、额叶、颞叶、枕叶、顶叶等部位均存在NSCs,NSCs呈圆形、椭圆形、星形、多角形及梭形,以圆形及星形多见;细胞0～4个突起不等,胞浆丰富,核呈圆形,染色质疏松,1～2个核仁不等。可见NSCs呈群状、集落样、对称分裂、单个存在等生长方式。海马、室下区、纹状体、额叶、颞叶、顶叶、枕叶等7个部位NSCs逐渐减少。结论36周胎龄不同部位NSCs在分布、形态、生长方式及数量上存在差异。     

The effects of maternal hyperoxia on fetal breathing movements, body movements and heart rate variation in growth retarded fetuses.

In hypoxemic intrauterine growth-retarded fetuses (IUGR) there is a reduction in the incidence of fetal movements and in fetal heart rate variation. A causal relationship with the impairment of fetal oxygenation has been suggested. In 16 IUGR fetuses and in 13 normally grown fetuses maternal hyperoxygenation was applied for 40 min to increase fetal PO2 levels. All IUGR fetuses had abnormal Doppler blood velocity waveforms of the umbilical artery suggesting an impaired uteroplacental exchange. The effect of hyperoxygenation on fetal breathing and body movements and on fetal heart rate was evaluated. In the IUGR fetuses there was a significant increase in fetal breathing and body movements and in heart rate variation during hyperoxygenation as compared to the preceding control period of 40 min. No significant changes in fetal breathing and body movements were found in the normally grown control fetuses. A surprising observation was the increase of the number of heart rate decelerations after discontinuation of the maternal hyperoxygenation. It is concluded that in IUGR fetuses the increase in fetal heart rate variation and the increase in the incidence of breathing and body movements during maternal hyperoxygenation substantiates the relationship between these variables and the oxygenation status of the fetus.     

Influence of fetal breathing movements on pulmonary hemodynamics in fetal sheep

During fetal development, pulmonary vascular resistance (PVR) is high, and, as a result, blood flow through the fetal lungs is low. Although PVR markedly decreases at the time of birth, the factors that regulate pulmonary blood flow (PBF) and PVR before and immediately after birth are not clear. Our aim was to examine the relationship between episodes of fetal breathing movements (FBM) and pulmonary hemodynamics during late gestation to further understand the relationship among lung luminal volume, phasic changes in intrapulmonary pressure, and PVR before birth. In chronically catheterized fetal sheep (120-128 d gestation; n = 5; term approximately 147 d), PBF and PVR were measured during periods of FBM and apnea. Episodes of FBM were divided into periods of accentuated (amplitude of >3.5 mm Hg change in tracheal pressure) and nonaccentuated periods of FBM. During accentuated episodes of FBM, mean PBF was increased to 159.5 +/- 23.4% (p < 0.0025) of the preceding apneic period and was associated with a 19.1 +/- 5.2% reduction in PVR. In addition, during accentuated episodes of FBM, the retrograde flow of blood through the left pulmonary artery was reduced to 90.1 +/- 1.0% of the preceding apneic period, which most likely contributed to the increase in mean PBF at this time. Although a change in PBF and PVR could not be detected during nonaccentuated FBM, compared with the preceding apneic period, PBF was linearly and positively correlated with the amplitude (change in pressure) of FBM. We conclude that PVR is decreased and PBF is increased during accentuated episodes of FBM, possibly as a result of phasic reductions in intrapulmonary pressures.     

The association between fetal body movements, eye movements and heart rate patterns in pregnancies between 25 and 30 weeks of gestation

Fetal eye movements, fetal body movements and fetal heart rate patterns were studied in healthy fetuses between 25 and 30 weeks of gestation in 21 recordings with a mean recording time of 83.5 min. In contrast with the older fetus, prolonged periods of absence as well as presence of fetal eye or body movements were uncommon. Especially absence of body movements for more than 15 min is extremely rare at this age. These findings emphasize that for the interpretation of fetal biophysical tests, gestational age should be taken into account. A linkage was demonstrated between fetal eye movements and fetal heart rate pattern and between fetal body movements and fetal heart rate pattern, but not between fetal eye movements and fetal body movements. The existence of fetal behavioural states could not be demonstrated.     

Effects of maternal anxiety on perception of fetal movements in late pregnancy

BACKGROUND: To determine whether maternal state and trait anxiety levels affect maternal perception of fetal movements in the third trimester. METHOD: Forty healthy pregnant nulliparous women not on medication and with a singleton, uncomplicated pregnancy were studied. Maternal anxiety was assessed using the Spielberger State-Trait Anxiety Inventory (STAI, Form-Y) at 36 gestational weeks. At term (37- 40 gestational weeks), fetal movements were recorded simultaneously by the mother and by an ultrasound observer. The ultrasound transducer was positioned to include a cross-section of the fetal trunk and of at least one fetal limb. The ultrasound observer pressed a push-button for as long as she saw a fetal movement on the ultrasound screen. The screen was placed out of sight of the pregnant woman, who pressed another push-button for as long as she felt a fetal movement. The signals were fed into two different channels of a cardiotocograph. Fetal heart rate (FHR) was recorded throughout the examination and classified as FHR patterns A, B, C, or D. Examination time was 120 min. Agreement between maternally recorded and sonographically recorded fetal movements was determined manually for each FHR pattern and was compared between women with low and high state and trait anxiety. The low state anxiety group had STAI scores ranging from 20 to 31, and the high state anxiety group had STAI scores from 32 to 57. The corresponding values for the low and high trait anxiety groups were 20 to 29 and 30 to 54. RESULTS: The agreement between maternally perceived and ultrasonographically recorded fetal movements did not differ between women with low and high state and trait anxiety in any FHR pattern. CONCLUSION: This study does not support that maternal anxiety--within the normal range--affects perception of fetal movements in late pregnancy.     

Effects of maternal starvation on hepatocyte proliferation in the late gestation fetal rat

Fetal growth retardation, a common end point for a variety of conditions affecting mother and fetus, is associated with reduced liver mass. We have performed studies to determine the mechanism for decreased liver mass in a maternal starvation model of fetal growth restriction in the rat. Pregnant dams were deprived of food for 48 h before delivery on embryonic day 19 (E19). Fetal body weight was not affected. However, fetal liver weight was reduced by approximately 15%. Immunostaining of fetal liver for proliferating cell nuclear antigen and flow cytometry on isolated fetal hepatocytes showed G1 cell cycle arrest in samples from starved dams. Based on our prior studies showing attenuated hepatic insulin signaling in the late gestation fetal rat, we tested the hypothesis that G1 arrest in our model might be due to altered nutrient signaling. Fetal plasma amino acid analyses showed no decrease in branched-chain amino acids, but arginine concentrations were decreased in fetuses of fasted mothers. Reduced arginine in E19 fetal hepatocyte culture media was associated with decreased DNA synthesis. Whereas levels of cyclins D and E were unchanged in fetal hepatocytes exposed to low arginine, cyclin E-dependent kinase activity was reduced. Low arginine also induced changes in the translational machinery, indicative of impaired signaling through the nutrient sensing kinase mammalian target of rapamycin. Our results are consistent with the hypothesis that restricted nutrient availability signals to the hepatocyte cell cycle in fetuses of fasted mothers, thereby accounting for decreased hepatocyte proliferation and liver mass.     

The umbilical artery blood flow velocity waveform in relation to fetal breathing movements, fetal heart rate and fetal behavioural states in normal pregnancy at 37 to 39 weeks

In 19 normal pregnancies between 37 and 39 weeks of gestation, the blood flow velocity waveform (FVW) of the umbilical artery was studied in relation to fetal breathing movements, fetal heart rate (FHR) and the fetal heart rate patterns (FHRPs) A and B. FHRP A is stable, with a narrow oscillation bandwidth, FHRP B shows a wider oscillation bandwidth. Although for state-assessment it is necessary to record three variables simultaneously, the linkage of these variables in the near-term healthy fetus is such, that FHRP A and B may be used for the assignment of behavioural states 1F and 2F. The FVW was characterized by the Pulsatility-Index (PI). Presence of fetal breathing movements strongly disturbed the regularity of the FVW. A significant inverse relationship between FHR and PI was established. A weighted regression coefficient was calculated: PI decreases 0.0075 with an increase of FHR of 1 beat per minute (PI140 = PI / 0.0075(FHR - 140]. The PI was higher during periods of FHRP A as compared to FHRP B. However, this difference disappeared, when the influence of FHR was taken into account by normalising all PIs to a standard heart rate level of 140 bpm. One should perform the umbilical artery blood flow measurements in absence of fetal breathing--(causing irregularity of the FVW) and body movements (because of accompanying FHR accelerations) and FHR should be taken into account when evaluating the FVWs.     

The effect of maternal hyperglycemia on gross body movements in human fetuses at 32–34 weeks' gestation

This study demonstrated that fetal gross body movements were not significantly altered by fluctuations in maternal plasma glucose concentration. Fetuses moved episodically a relatively constant amount of time whether mother received water orally, 50 g of glucose orally or a 25 g bolus of glucose intravenously. In addition, depending on the length of the observational epoch, the incidence of fetal gross body movements differed. As the length of the observational period increased, the chance of finding no fetal gross body movements decreased and at intervals of 24 min duration, fetal gross body movements were absent in only 2% of 24 min periods examined, irrespective of whether they had received water orally, 50 g of glucose orally or 25 g of glucose intravenously. It is concluded that maternal carbohydrate intake was not an important determinant of fetal body movements in healthy fetuses at 32–34 weeks' gestation.     

Stimulatory effect of theophylline on regulation of fetal breathing movements

We have performed the fetal CO2 response test on eight mature lambs in utero and have found that theophylline is a respiratory stimulant over a wide range of PaO2 and pHa. Theophylline produces significant increase in slope of P100, Pmax, and VEq response curves and significant increase in P100, Pmax, f, and VEq responses at PaCO2, 65 torr. It also produces significant lowering of the naturally high fetal absolute threshold to CO2, i.e., PaCO2 at which breathing starts during the CO2 test. "Offset" threshold, i.e., PaCO2 when breathing stops after the test, is the same with and without theophylline and equal to absolute threshold with theophylline. Our studies indicate that: (1) theophylline lowers fetal threshold and increases sensitivity to CO2; (2) increased sensitivity is expressed mainly by heightened Pmax (i.e., the equivalent of tidal volume) with some contribution of f particularly at high PaCO2; (3) decreased CO2 threshold is best assessed by determination of absolute threshold rather than the conventional x-axis intercept method; (4) the low offset threshold is consistent with our understanding that arousal is a requisite for generation and maintenance of fetal breathing; (5) theophylline is as effective a respiratory stimulant during fetal acidemia and hypoxemia as it is under normal conditions; and (6) a number of serious reservations must be held regarding use of theophylline during low pHa, low PaO2 states.     

Preterm delivery and calculation of survival rate below 28 weeks of gestation

AIM: To estimate the number of still- and live-births below 28 wk of gestation in a 2-y period in Denmark, and to determine how the calculated survival rates vary using three different denominators: 1) the number of infants actively treated in the Neonatal Care Units, NNUs, 2) the number of all live-born infants, and 3) the number of all births, including stillbirths. METHODS: The number of stillbirths and live-born infants at 20 to 27 wk of gestation was estimated over a 2-y period in Denmark. Data on live-born infants and survival rates were obtained from a national prospective study and the National Births Register. The number of women hospitalized owing to spontaneous abortion was obtained from The Danish National Health Register; the number of stillbirths was calculated from these data. RESULTS: The estimated number of both still- and live-births was similar in every week from 20 to 27 wk of gestation; approximately 1 per 1000 live-births at each gestational week. At from 23 to 25 wk of gestation the overall chances of survival varied significantly depending on the denominator: actively treated infants 46% (CI 95%; 37%-54%), all live-born infants 34% (CI 95%; 27%-41%), all births including stillbirths 14% (CI 95%: 11-17%). CONCLUSION: The chances of survival for the intrauterine fetus below 26 wk of gestation are significantly lower than the reported survival rates from the NNUs. The low percentage of fetuses delivered before 26 wk of gestation classified as live-born renders the reported birth-rates sensitive to differences in the way "live-born" is interpreted.     

Effects of behavioural states on cardiac output in the healthy human fetus at 36-38 weeks of gestation

Doppler velocity waveforms from atrioventricular valves were recorded in 20 healthy fetuses at 36--38 weeks of gestation during both behavioural states 1F (quiet sleep) and 2F (active sleep). No significant changes were found in the ratios between the velocities during early passive ventricular filling and active ventricular filling (E/A ratios) at the level of both mitral and tricuspid valves when the measurements obtained during states 1F and 2F were compared. Moreover, during state 2F the left ventricular output increased and the right ventricular output decreased, resulting in a marked modification of the right to left cardiac output ratio. Our data suggest a redistribution of cardiac output in favour of the left side of the heart during state 2F.     

Quantitated fetal heart rhythm at 20, 32 and 38 weeks of gestation and dependence on rest-activity patterns.

Quantitative parameters of fetal heart rate (FHR) were automatically analysed at 20, 32 and 38 weeks of pregnancy. FHR was obtained both by the fetal ECG method and by wide range Doppler ultrasound with autocorrelation. At 32 and 38 weeks, FHR was studied in relation to fetal rest-activity according to the fetal behavioural state concept (coincidence 1F and 2F). Basal fetal heart rate was significantly higher at 20 weeks of gestation than at 32 and 38 weeks. The number of accelerations increased significantly from 20 weeks to 32 and 38 weeks for C2F periods. Parameters of FHR variability, i.e. ID, ABB, LTI indices and bandwidth, were higher during periods C2F compared to periods C1F. Lowest values of all four parameters were found at 20 weeks gestation. The ID index, which is a measure of short-term variability increased significantly between 32 to 38 (C2F). The absolute values of ID, ABB and LTI were lower for ultrasound recordings than for the fetal ECG.     

Hypocarbia during the first 24 postnatal hours and white matter echolucencies in newborns < or = 28 weeks gestation

The purpose of the present study was to test the hypothesis that newborns < or = 28 wk gestation who have a PCO(2) measurement in the lowest gestational age-specific quartile (hypocarbia) on the first day of life are not at increased risk for ultrasonographic white matter echolucency (EL) after adjustment for confounders. The sample consisted of 799 infants < or = 28 wk gestation born during 1991-1993. Forty-eight infants with EL were classified as cases and compared with 751 controls, i.e. those without EL. We performed univariable comparisons, stratified analyses, and multivariable logistic regression. In the univariable analyses, hypocarbia on the first day of life was associated with an increased EL risk. The odds ratios for the hypocarbia-EL relationship were prominently elevated in the strata of infants who did not have other major risk factors for EL (e.g. gestational age 26-28 wk, normothyroxinemia, no characteristics of antenatal infection). In the multivariable analyses, the association diminished after adjustment with a hypocarbia propensity score (odds ratio = 1.7; 95 % confidence interval, 0.8-3.2) or with potential confounders.