Neonatal transverse cerebellar diameter in normal and growth-restricted infants

OBJECTIVE: To assess the transverse cerebellar diameter (TCD) in preterm and term neonates with normal growth or growth restriction. METHODS: TCD was sonographically measured after birth in 404 neonates born between 23 and 42 weeks of gestation. The study included two groups: Group 1: 334 appropriately grown for gestational age (AGA) neonates (both birthweight (BW) and head circumference (HC) were between the 3rd and 97th centiles), which were subdivided into two subgroups according to the HC measurements. Group 2: 70 small for gestational age (SGA) neonates (BW <3rd centile), were further divided into three subgroups according to HC measurements. RESULTS: In Group 1 of AGA neonates, a linear growth function was observed between the TCD and GA (R = 0.914, P < 0.00001, TCD = 0.279 + 0.142 X GA), and between TCD and HC (R = 0.886, P < 0.00001, TCD = -0.333 + 1.777 X HC). The percentage of neonates with normal TCD (> or =10th centile) was more than 85% of the AGA and asymmetric SGA subgroups, and 60.7% of the microcephalic SGA subgroup (P < 0.02). CONCLUSIONS: This study provides normative data of neonatal TCD across gestational age. TCD measurement via sonography is a new adjunctive criterion for objectively assessing gestational age in infants when a precise determination of gestational age is necessary. This is very important since utility of the TCD is effective for both AGA and asymmetric SGA infants.     

Internal jugular vein blood flow in normal and growth-restricted fetuses

OBJECTIVE: To assess internal jugular vein blood flow patterns during the second half of pregnancy in normal and growth-restricted fetuses. METHODS: We did Doppler ultrasound studies of internal jugular veins and the inferior vena cavas longitudinally on 21 normal singleton fetuses from 20 weeks to term, and on eight growth-restricted fetuses with absent end-diastolic flow at the umbilical artery (UA). The three components of the venous flow velocity waveforms were used to calculate peak velocity ratio: Peak systolic velocity (S wave) minus reverse peak velocity (R wave) divided by peak velocity during early diastole (D wave) and velocity time integral ratio: systolic velocity time integral minus reverse velocity time integral divided by velocity time integral during early diastole. Statistical analysis of longitudinal measurements used K-related samples Friedman test; groups were compared with Mann-Whitney U test and chi(2) test. RESULTS: In normal fetuses we found significant increases in peak velocity ratio and velocity time integral ratio of internal jugular veins and the inferior vena cavas throughout gestation. The mean +/- standard deviation (SD) of the internal jugular veins peak velocity ratio (1.12 +/- 0.4 versus 1.46 +/- 0.15, P <.05) and velocity time integral ratio (1.1 +/- 0.2 versus 1.55 +/- 0.17, P <.05) were significantly lower in growth-restricted fetuses compared with normal fetuses at 28-32 weeks' gestation but inferior vena cava indices were not. None of the eight growth-restricted fetuses had umbilical venous pulsations or changes in inferior vena cava or ductus venosus blood flow patterns. All had arterial pH above 7.15 at birth. CONCLUSION: Growth-restricted fetuses with absent end-diastolic velocity in the UA have changes in internal jugular vein blood flow patterns that probably indicate increased cerebral blood flow, more evidence of redistribution of blood flow in growth-restricted fetuses that can be used to maintain them.     

Differences in fat and lean mass proportions in normal and growth-restricted fetuses

OBJECTIVE: The purpose of this study was to assess fetal subcutaneous fat and lean mass areas as predictors of fetal growth restriction. STUDY DESIGN: Seventeen severe fetal growth-restricted (abdominal circumference, < 2 SD) fetuses and 20 control fetuses underwent ultrasound measurements of subcutaneous fat, lean mass, and standard biometry. Thigh subcutaneous fat and lean mass were measured on enlarged ultrasound axial images (subcutaneous fat area = total cross sectional area - lean mass area [bone + muscle areas]). Subcutaneous fat and lean mass areas were expressed as a percentage of the total cross-sectional area and were normalized to femur length and head circumference. Measurements were modeled as a function of fetal growth-restriction status and week of gestation with multiple linear regression. RESULTS: Fetal growth-restriction fetuses showed reductions in fat and lean mass (in standard biometry) and showed a disproportionate reduction in fat mass compared with lean mass. These were all associated significantly with fetal growth restriction. CONCLUSION: Fetal growth-restricted fetuses have reduced subcutaneous fat and lean mass compared with control fetuses; a further reduction occurs in subcutaneous fat concentration compared with the reduction in lean mass when fat is normalized for body size, with either head circumference or femur length. Fat-to-bone proportions may be useful in distinguishing the small for gestational age fetus who is truly fetal growth restriction from the constitutionally small fetus.     

Simultaneous measurements of umbilical venous, fetal hepatic, and ductus venosus blood flow in growth-restricted human fetuses

OBJECTIVE: The purpose of this study was to evaluate the changes in the distribution of the umbilical venous blood flow to the liver and to the ductus venosus in intrauterine growth-restricted human fetuses in relationship with dilation of the ductal isthmic diameter. STUDY DESIGN: Umbilical venous flow, ductus venosus blood flow, and blood flow to the fetal liver were measured in 56 severely intrauterine growth-restricted fetuses with an abnormal pulsatility index of the umbilical artery and were compared with 137 normal control fetuses. Percentages of umbilical venous blood flow through the ductus venosus and to the fetal hepatic lobes were calculated. Z-scores for control fetuses and intrauterine growth-restricted fetuses were constructed by the evaluation of the inverted smoothed percentiles. The distributions of the Z-scores was compared with a 1-sample t-test. RESULTS: The ductus venosus blood flow that was corrected for fetal weight was increased significantly in intrauterine growth-restricted fetuses compared with control fetuses (P=0); the median values (interquartile range) for comparable ages of gestation was 41.3 mL/min/kg (range, 26.2-64.0 mL/min/kg) and 30.8 mL/min/kg (range, 19.9-42.8 mL/min/kg), respectively. As a consequence, ductus venosus shunting was increased in intrauterine growth-restricted fetuses compared with control fetuses (P =0). In 23 of 30 intrauterine growth-restricted fetuses, the percentage of umbilical blood flow that was shunted through the ductus was>90th percentile of control fetuses. Ductal diameters were significantly greater in growth-restricted fetuses than in control fetuses (P =.0001). The percentage of blood flow to the right lobe showed a significant reduction (P =.0223), with evidence of reversed blood flow from the right lobe and portal system into the ductus venosus that was provided both by volume blood flow calculations and by direct pulsed Doppler waveform direction. CONCLUSION: In severe intrauterine growth-restricted fetuses, Doppler examination of blood flow volume proved a significant increase in the shunting of umbilical vein blood flow through the ductus venosus that was associated with the dilation of the ductal isthmic diameter. These changes provide a relatively constant blood flow to the heart and brain at the expense of fetal hepatic perfusion.     

Doppler, cardiotocography, and biophysical profile changes in growth-restricted fetuses

OBJECTIVE: To assess from diagnosis to delivery the Doppler studies of the umbilical artery, middle cerebral artery, umbilical vein, ductus venosus, and amniotic fluid index of fetuses with idiopathic growth restriction. METHODS: A total of 145 singleton growth-restricted fetuses with abnormal umbilical artery pulsatility indexes were studied. Cesarean delivery was performed because of abnormal biophysical profile or nonreassuring fetal heart rate pattern. RESULTS: There were 4 fetal and 50 neonatal deaths. Two growth-restricted groups were identified: Group A (n = 44) included fetuses in whom all measures became abnormal preceding an abnormal biophysical profile or nonreassuring nonstress test. Group B (n = 101) included fetuses in whom 1 or more measures were normal at the time of cesarean delivery. There was no statistically significant difference in perinatal morbidity and mortality between the 2 groups. Neonatal death was increased in fetuses with umbilical artery reversed flow (odds ratio 2.34, 95% confidence interval 1.16-4.73; P < .05) and ductus venosus reversed flow (odds ratio 4.18, 95% confidence interval 2.01-8.69; P < .05). A significant correlation was also found between low birth weight and adverse perinatal outcome. CONCLUSION: In fetuses with idiopathic growth restriction, 1) low birth weight, 2) umbilical artery reversed flow, and 3) ductus venosus absent or reversed flow are associated with an increased perinatal morbidity and mortality.     

Weight estimation for low birth weight fetuses and macrosomic fetuses in Chinese population

Objective  

Compared with normal birth weight fetuses (2,500–4,000 g), accurate fetal weight estimation for fetuses with low or excessive weight is considered more important for fetal compromise prediction and labor management. New formulas were developed to estimate weight for low birth weight (LBW) fetuses and macrosomic fetuses, respectively.     

Fetal facial expressions in small-for-gestational-age and growth-restricted fetuses

Objective: To evaluate the frequencies of fetal facial expressions among appropriate-for-gestational-age (AGA), small-for-gestational-age (SGA), and growth-restricted (FGR) fetuses.

Methods: Four-dimensional (4D) ultrasound was used to examine the facial expressions of 50 AGA, 25 SGA, and six FGR fetuses between 28 and 35 weeks of gestation. The frequencies of seven facial expressions during 15-minute recordings were assessed. Comparison of facial expressions among the three groups was performed.

Results: Mouthing was the commonest facial expression at 28–35 weeks, and the frequency of mouthing was significantly higher than those of the other six facial expressions in AGA fetuses. Mouthing was the most frequent facial expression, but there was no significant difference in the frequency among mouthing, smiling and blinking in SGA fetuses. Moreover, mouthing displayed a significantly higher frequency than the other facial expressions, except for yawning, smiling, and blinking in FGR fetuses. However, there was no significant difference in the frequency of each facial expression among the three groups.

Conclusions: Our results suggest that the frequencies of fetal facial expressions are not decreased in either SGA or FGR pregnancies. The absence of a decrease in the frequency of each fetal expression in FGR fetuses may be due to increased brain blood flow because of the brain-sparing effect. Moreover, accelerated maturation and development of the brain function, especially the central dopamine system, might be suspected in SGA and FGR fetuses.     

The relationship between fetal activity and behavioral states and fetal breathing movements in normal and growth-retarded fetuses

The incidence of fetal breathing was studied during the course of behavioral state observations on 28 low-risk fetuses between 32 and 40 weeks' gestational age and on 12 growth-retarded fetuses between 36 and 40 weeks. Real-time ultrasound scanners were used to detect fetal eye, body, and breathing movements, and the fetal heart rate was recorded continuously. The mean duration of the observation sessions was 110 minutes. The mean incidence of fetal breathing was greater during periods of fetal activity (body and eye movements present, greater heart rate variability) than during quiescence (body and eye movements absent, narrowed heart rate variability) at all gestational ages studied in both low-risk and growth-retarded fetuses. During periods when one of the state variables (body movements, eye movements, heart rate pattern) was in its active condition while the other two were quiet, or the reverse, the incidence of fetal breathing was intermediate between those found when all three state variables were in agreement. After behavioral states had developed, at 38 and 40 weeks, the mean incidence of fetal breathing in the low-risk fetuses was greater during active states than during the quiet state. There was no apparent increase in the degree of linkage between fetal breathing and other expressions of fetal activity after the emergence of behavioral states.     

Caliber of the coronary sinus in fetuses with cardiac defects with and without left persistent superior vena cava and in growth-restricted fetuses with heart-sparing effect

OBJECTIVE: To assess reference ranges for fetal coronary sinus (CS) diameter and to compare them with values from fetuses showing heart defects with and without left superior vena cava (LSVC) as well as with severe intrauterine growth retardation and heart-sparing effect on color Doppler. METHODS: The coronary sinus was visualized on two-dimensional ultrasound in a plane slightly caudal to the apical four-chamber view. For the normal range of the size of the CS in relation to gestational age, data was collected from 108/114 (95%) normal fetuses with good visualization between 20 weeks' gestation and term. Abnormal conditions comprised two groups: group 1 consisted of 52 fetuses with heart anomalies, including three subgroups: 11 fetuses with isolated LSVC emptying into the coronary sinus, 12 fetuses with LSVC associated with structural heart defects and 29 fetuses with structural heart defects but without LSVC. Group 2 consisted of 11 fetuses with severe intrauterine growth retardation and dilated coronary arteries as seen by color Doppler ultrasound. RESULTS: Under normal conditions, there was a significant increase in the CS diameter with advancing gestational age (1.2-2.7 mm). Significant dilatation was found only in the two groups with LSVC (range 2.7-6.5 mm), independent of whether the finding was isolated or associated with cardiac defects. CONCLUSION: CS visualization and measurements are easily feasible in the human fetus in the apical four-chamber view. Significant dilatation of the CS is a sign of LSVC. The examiner should be aware of this condition as such dilatation is commonly falsely diagnosed as atrial or atrioventricular septal defect.     

The variability of fetal breathing movements in normal human fetuses at term

With the use of a B-scan phase-locked tracking system, 108 observations of fetal breathing were performed on 97 normal antenatal patients at term. One hundred thirty-three recorded segments of fetal breathing movements were obtained. Breath-to-breath variability was analyzed in 79 segments and expressed as a coefficient of variability. The mean coefficient of variability was 28.6% ± 13.2%, and a histogram plot revealed a normal distribution. All fetuses had normal antepartum testing and all Apgar scores and neonatal courses were normal. The potential application of human fetal breathing variability as a test for fetal health is discussed.     

The outcome of macrosomic fetuses in a low risk primigravid population.

OBJECTIVES: To ascertain whether fetal macrosomia is associated with increased maternal and neonatal morbidity in uncomplicated, singleton, vertex deliveries at term in primigravid women. METHODS: This was a retrospective population based survey of 8617 deliveries over an 11-year period. These were stratified into three birthweight categories: 2500-3999 g (n=7854), 4000-4499 g (n=666) and > or =4500 g (n=97). Outcome variables included maternal characteristics, delivery details, maternal and perinatal morbidity data. RESULTS: Increased BMI and incidence of Caucasian ethnicity and non-smoking were significantly greater in macrosomic compared with non-macrosomic infants (P<0.001). Increasing birthweight (especially > or =4.5 kg) was associated with significantly (P<0.001) lower rates of spontaneous onset of labor, spontaneous vertex deliveries and significantly higher rates (P<0.001) of maternal and neonatal morbidity. CONCLUSIONS: This study supports the notion of expectant management in suspected fetal macrosomia in low risk primigravid women until 40 weeks gestation. Thereafter, the safest mode of delivery is controversial, with some evidence pointing to elective cesarean section as a viable alternative in these women. A prospective RCT is needed to evaluate the best management option in terms of fetal and maternal outcome in cases of suspected macrosomia after 40 weeks' gestation.