SGA Fetuses Research Articles

Placental Expression of Peroxisome Proliferator-Activated Receptor γ (PPARγ): Relation to Placental and Fetal Growth

The nuclear receptor peroxisome proliferator activated receptor γ (PPARγ) contributes to placental development and thus to the maternofetal transfer of oxygen and nutrients that allow for prenatal growth. We tested the hypothesis that placental PPARγ expression relates to placental and fetal growth. Placentas (n = 116) were collected at term delivery of singleton infants who were born small- (SGA), appropriate- (AGA), or large-for-gestational-age (LGA) (n = 32 SGA, 55 AGA, and 29 LGA). Placentas and newborns were weighed at birth. Real-time PCR was used to assess placental expression of PPARγ as compared to the housekeeping gene GAPDH. PPARγ expression in placentas from AGA and LGA infants was nearly 2-fold higher than in placentas from SGA infants. Placental PPARγ expression associated positively to placental and/or fetal weight at birth, particularly within the SGA subpopulation (P = 0.001). PPARγ expression was found to be low in placentas of SGA fetuses and to associate positively to fetal and placental weights within this subpopulation.

Twin Pregnancies and Aortic Intima Media Thickness: A New Model

Objective: Previously we showed that aorta intima-media thickness (aIMT) in IUGR fetuses with Doppler abnormalities is higher than in AGA. The aim of the present study is to validate this finding in twin pregnancies with the co-twin affected by IUGR or SGA.Methods: Prospective longitudinal study has been performed in our University hospital between January 2009 and February 2011. IUGR co-twin was defined as fetuses with estimated fetal weight (EFW) < 10th percentile with abnormal Doppler velocimetry (umbilical artery PI > 2 SD) and SGA fetuses with EFW< 10th percentile and normal Doppler velocimetry. aIMT was evaluated during routine third trimester ultrasonography.Results: Sixty-three twin pregnancies were enrolled in the study. Among them 80 twins were AGA, 20 IUGR and 26 SGA. Median GA at birth was 35 weeks (range 32-36), and median birth weight 1665 g (range1246-1840), 2172 g (range 1838-2333), 2295 (range 1910-2550) in IUGR, SGA and AGA, respectively, showing a statistical difference between IUGR vs AGA (p< 0.0001) and vs SGA (p=0.003). Median gestational age at aIMT measurements was 30 weeks (range 29-32). There was a significative difference in aIMT between IUGR, SGA and AGA.Conclusions: aIMT is higher in IUGR compared to SGA vs AGA and in SGA vs AGA fetuses, highlighting that Doppler velocimetry and birth weight are predictors of aorta stiffness. Moreover, to our knowledge this is the first study considering aIMT in twin pregnancies, which may be considered a model of study to detect early cardiovascular markers in the same environment.

OP31.06: Pregnancy complications and neonatal outcome in spontaneous and assisted reproductive twin pregnancies

between IUGR and SGA (P = 0.003), IUGR and AGA (P < 0.0001), SGA and AGA P < 0.003). IUGR showed a significant difference in perinatal morbidity between SGA and AGA (P < 0.0001). Conclusions: The present study highlights that aIMT is higher in IUGR compared to SGA vs. AGA and in SGA vs. AGA fetuses, highlighting that Doppler velocimetry and birth weight are predictors of aorta stiffness. Moreover, to our knowledge this is the first study considering aIMT in twin pregnancies, which may be considered a model of study to consider early cardiovascular markers in the same environment.

OP31.04: Marginal umbilical cord insertion in sIUGR monochorionic twins does not correlate with TTTS and optimal timing of delivery avoid adverse perinatal outcome

between IUGR and SGA (P = 0.003), IUGR and AGA (P < 0.0001), SGA and AGA P < 0.003). IUGR showed a significant difference in perinatal morbidity between SGA and AGA (P < 0.0001). Conclusions: The present study highlights that aIMT is higher in IUGR compared to SGA vs. AGA and in SGA vs. AGA fetuses, highlighting that Doppler velocimetry and birth weight are predictors of aorta stiffness. Moreover, to our knowledge this is the first study considering aIMT in twin pregnancies, which may be considered a model of study to consider early cardiovascular markers in the same environment.

OC12.04: Increased umbilical artery pulsation in fetal growth restriction increases the risk of ST‐depression of the fetal electrocardiogram during labor

CD and CD for NRFS alone or in combination with MCA Doppler was assessed by decision tree analysis. Results: Retrograde net blood flow in aortic isthmus was observed in 8.3% (14/169) of the cases and only within the group of fetuses with MCA vasodilation (PI < 5th centile). Among the overall study population, cases with reversed aortic isthmus blood flow were associated with a significantly higher risk of CD (85.7% vs. 36.8%, P < 0.001) and CD for NRFS (85.7% vs. 24.5%, P < 0.001) than those with antegrade blood flow. Decision tree analysis indicated that incorporation of aortic isthmus showed an additional predictive value to brain Doppler abnormalities. Among the group with MCA vasodilation, reversed aortic isthmus blood flow allowed discrimination of cases with high or moderate risk of CD (85.7% vs. 54.5%, P < 0.01) and CD for NRFS (85.7% vs. 40.9%, P < 0.05). Conclusions: Identification of aortic isthmus reversed blood flow identifies a subgroup of term SGA fetuses with middle cerebral artery vasodilation with the highest risk of emergency cesarean delivery for non-reassuring fetal status.

A hospital-based birth weight analysis using computerized perinatal data base for a Chinese population

Objectives. We aimed to construct birth weight-for-gestational age nomograms based on a computerized perinatal data base in a hospital-based Chinese population.Methods. Retrospectively collected 28,052 singleton deliveries at Women and Children's Medical Center, Guangzhou, China. Standard curves of birth weight from 27 to 43 week's gestation were computed. The nomograms included the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles and standard deviations.Results. 79.9% pregnant women delivered between 38, 39, and 40 gestational week, and the mean birth weights are 3160, 3282, and 3388 g, respectively. Preterm birth is 5.7%. In general, male birth weights are greater than females at each gestational week. The hospital-based Chinese population birth weight is lower than that of North American and Scandinavian population.Conclusions. A different standard birth weight is needed for different population. A hospital-based birth weight curve by gestational week is established, which can be a useful tool to estimate intrauterine fetal growth to define SGA or LGA fetuses.

Cerebral blood perfusion and neurobehavioral performance in full-term small-for-gestational-age fetuses

The purpose of this study was to evaluate changes in cerebral blood perfusion and middle cerebral artery (MCA) Doppler in full-term small-for-gestational-age fetuses (SGA) and to explore their association with neonatal neurobehavioral performance. Frontal brain perfusion that was measured by fractional moving blood volume (FMBV) and MCA Doppler pulsatility index were assessed in 60 SGA fetuses with normal umbilical artery Doppler results that were matched with adequate-for-gestational-age fetuses. Neonates were evaluated with the Neonatal-Behavioral-Assessment-Scale (NBAS). The proportion of SGA fetuses with increased FMBV (35% vs 5%; P < .001) and decreased MCA Doppler pulsatility index (15% vs 1.7%; P < .01) was significantly higher. SGA fetuses showed poorer NBAS scores in all areas. Increased FMBV identified SGA fetuses with the highest risks of abnormal NBAS in social-interactive (odds ratio, 7.8), attention (odds ratio, 22.8), and state-organization (odds ratio, 25.0). Abnormal MCA Doppler identified SGA with abnormal scores in motor area (odds ratio, 10.7). Increased brain blood perfusion discriminates SGA fetuses that are at risk for abnormal neurobehavior.

Doppler Velocimetry In Normal And Hypertensive Pregnancy

Objectives: This study was conducted to find doppler velocimetric indices of the uterine and umbilical artery in normotensive and hypertensive pregnancy and to detect SGA fetuses with abnormal velocimetric index.Study design: Two hundred women of third trimester in antenatal clinic were studied: hypertensive and normotensive 100 each. Baseline investigations and doppler velocimetry of both the uterine arteries and umbilical artery was done. Statistical analysis of data was done using the EPI-info 6 (CDC (US) / WHO). Result: The mean SD ratio of Uterine Artery decreased from 6.15 at 32-34 weeks to 3.06 at 38-40 weeks in the hypertensive group. Abnormal uterine artery doppler findings were reported in 55% of hypertensives. In the hypertensive group 92.10% of cases with SGA babies and 32.25% of cases with AGA babies had abnormal uterine artery Doppler findings.Conclusion: Abnormal doppler findings of the uterine and umbilical are more common in SGA fetuses.

602: Genome-wide array-based copy number profiling in placentas from unexplained stillbirth

While precise estimates vary, karyotypic abnormalities are present in 6-12% of stillbirths (SB). However, due to inherent limitations of the conventional cytogenetic techniques of FISH and karytoype, the contribution of genomic aberrations is likely underrepresented. We hypothesized that use of high-resolution genomic profiling by aCGH may overcome such limitations, and simultaneously allow for assessment of genomic copy number variants (CNV). We thus sought to determine by aCGH whether structural variants in placental tissue accompany SB in a prospectively attained, well-characterized case-control cohort. Prospectively acquired SB cases >22 weeks underwent amniocentesis for karyotype, maternal toxicology, serology and vaginal microbiology. At delivery multiple placental biopsies were obtained alongside fetal blood sampling, microbial sampling, complete placental histology and fetal autopsy. Classification of ”unexplained” SB was by strict criteria after multidisciplinary audit and included both appropriate (AGA) and small (<10th%) for gestational age (SGA). Placental DNA was extracted and tested by Illumina HumanCNV370-Duo chip to enable whole genomic CNV coverage. 24 SB meeting criteria for “unexplained SB” were studied by aCGH. These included 11 AGA and 13 SGA fetuses. Comparative analysis against AGA (n=10) and SGA (n=14) liveborns was performed. A total of 32 CNVs larger than 100 kb were detected in 18 placentas: 9/24 SB and 9/24 control placentas. Of the 32 detected CNVs, 24 were copy number gains and 8 were copy number losses. The detected CNVs were associated with different chromosomes and their sizes ranged from 142 kb to 2.9 Mb. Evaluation of stillbirths with aCGH using placental tissue is feasible, and enables whole-genome profiling of unexplained stillbirths. Our findings illustrate the power of such approaches to identify genomic variants, and lay the groundwork for future population-based analysis.

Gender Specificity of Body Adiposity and Circulating Adiponectin, Visfatin, Insulin, and Insulin Growth Factor-I at Term Birth: Relation to Prenatal Growth

Fetal development is thought to be gender specific for adiposity and circulating insulin and IGF-I but not adipokinemia, as judged by serum visfatin and adiponectin at term birth. We studied the potential relationship between these gender specificities and fetal growth. The study was conducted at a university hospital. Subjects included 96 strictly matched neonates born appropriate for gestational age (AGA; 24 girls, 24 boys) or small for gestational age (SGA; 24 girls, 24 boys). Outcomes included serum insulin, IGF-I, visfatin, total and high-molecular-weight (HMW) adiponectin, osteocalcin at term birth, and neonatal body composition by absorptiometry. Cord insulin and IGF-I levels were higher in girls than boys (P < or = 0.01), in both the AGA and SGA subpopulation. In AGA newborns, fat and lean mass were each gender specific (P < 0.0001), whereas visfatin and total and HMW adiponectin were not. Conversely, in SGA newborns, visfatin and HMW adiponectin were gender specific (higher levels in girls), whereas body adiposity was not. In SGA fetuses, the distribution of adiponectin isoforms was in both genders shifted toward HMW (P < 0.005 vs. AGA). Cord osteocalcin did not differ by either gender or birth weight. At term birth, the gender specificity of adiposity and circulating visfatin and HMW adiponectin appeared to depend on prenatal growth, whereas the gender specificity of insulin and IGF-I levels did not. The fetal shift in adiponectin isoforms may contribute to explain why SGA newborns tend to be hypersensitive to insulin.

Screening for Intrauterine Growth Restriction

Fetal chromosomal and structural anomalies, prematurity and poor placentation account for 90% of poor perinatal outcome. The first two causes are discussed elsewhere in this issue. Poor placentation is responsible for developing of preeclampsia and/ or intrauterine growth restriction (IUGR). As preeclampsia is also discussed elsewhere in this issue, in this article we will focus on screening for IUGR particularly with ultrasound. IUGR is defined by failure of the fetus to achieve its genetically predetermined growth potential.1 In clinical practice neonates with a birthweight at or below the 10th percentile and fetuses with an ultrasound estimated weight at or below the 10th percentile for gestational age are considered small (small for gestational age-SGA). The vast majority of these fetuses are not malnourished and do not show increased perinatal morbidity and mortality. A small number of SGA fetuses will be malnourished and IUGR.2 IUGR complicates approximately 5 to 10% of pregnancies (depending on the definition used) and is a major contributor of poor perinatal outcome and long-term consequences.3-6

P41.08: Abnormal uterine artery Doppler flow velocimetry detected after the 34th week does not affect pregnancies complicated by fetal growth restriction

artery PI, had increased risk for Cesarean section and lower birth weight, lower gestational age at delivery, lower apgar scores and higher need for neonatal intensive care. Uterine Doppler test have a positive prediction value of 58% to predict adverse perinatal outcome and therefore it could be useful to assess SGA fetus with normal umbilical Doppler. CPR at diagnosis of SGA was not useful to assess the subsequent adverse outcome.

SMALL FOR GESTATIONAL AGE FETUS

Objective: To evaluate the role of Colour Doppler Ultrasound in the management of small forgestational age fetus. SGA or IUGR. Design: Descriptive study. Place &amp; duration of study: Study performed in theDeptt. of Radiology &amp; Deptt. of Gynae. &amp; Obstetrics in Allied Hospital, Faisalabad from August 2005 to July 2006.Material &amp; Methods: This study was carried out on 45 patients admitted through antenatal clinic having suspicion ofcarrying small for gestational age fetus. A brief clinical record including age, parity, nutritional status, intercurrent illness,per-vaginum bleeding, history of drug intake, smoking, past obstetrical history was recorded. Methods involved inscreening SGA fetuses were measurement of Symphyseal Fundal Height chart &amp; Ultrasound biometry, Biophysicalprofile (BPP), Cardiotocography (CTG), Middle cerebral and Umbilical Arteries Doppler studies were performed afteradmission in the management of SGA fetuses. All these information were recorded in a specially designed Performa.Results: Out of 45 SGA fetuses 15(33.3%) were constitutionally small, 20(44.4%) had history of pre-eclampsia,2(4.4%) had cardiac disease, 3(6.6%) had placental abnormalities, 5(11.1%) had multiple gestations. Gestation ofpatients ranged between 30-36 weeks. Umbilical Artery Doppler was used as the primary surveillance tool. Smallfetuses with normal Doppler and anomaly scan were managed on out-patient basis with fortnightly Doppler ultrasound.15 patients (33.3%) with normal end-diastolic flow were delivered at 37 weeks. 20 patients (44.47%) with absent orreversed end-diastolic flow were delivered at 34-35 weeks. 10 patients (22.2%) at 30 weeks gestation with abnormalDoppler study were managed on CTG (Cardiotocography) &amp; biophysical profile over a period ranging between 1-14days. Perinatal mortality was 8.8% (4 cases) mostly due to extreme prematurity. Conclusion: Doppler ultrasound isa very helpful tool in the management of small for gestational age fetuses &amp; it reduces perinatal morbidity &amp; Mortality.

Intrauteriner Tod des Feten bei präkonzeptionellem Diabetes, Gestationsdiabetes und Schwangerschaften ohne diabetische Stoffwechsellage. Ergebnisse der Perinatalstatistik Niedersachsen

The prevalence of intrauterine fetal death as well as the relevant risk factors in pregnancies of women with preconceptional and gestational diabetes mellitus and non-diabetic women were investigated. The data of the Perinatal Registry of Lower Saxony between 1987 and 1999 for pregnancies of women with preconceptional diabetes mellitus (PDM, n = 3351), gestational diabetes mellitus (GDM, n = 3954) and women without diabetes mellitus (non-diabetic pregnancies, NDM, n = 887,779) were retrospectively analysed. Intrauterine fetal death occurred in 46 women with PDM (1.35 %), 32 women with GDM (0.79 %) and 2756 non-diabetic women (0.31 %). The odds ratio (OR, 95 % CI) for PDM vs. NDM was 4.468 (3.332 - 5.992; p < 0.01) and for GDM vs. NDM it was 2.595 (1.829 - 3.682; p < 0.01). The percentage of death, which occurs before the 32nd week of gestation, was 13 % in pregnancies with PDM, 12.5 % in pregnancies with GDM and 27.7 % in non-diabetic pregnancies. 50 % of fetal deaths in the PDM group, 43.8 % of those in the GDM group and 39.3 % of those in the NDM group occurred after the 36th week of gestation. The percentages of dead fetuses who were under the 10th percentile of growth (small for gestational age, SGA), in pregnancies with PDM, GDM and NDM were 15.2 %, 6.3 %, and 28.7 %, respectively. The percentages of dead fetuses above the 90th percentile of growth (large for gestational age, LGA) were 41.3 % (PDM), 37.5 % (GDM), and 8.7 % (NDM), (p < 0.01 for PDM vs. NDM and for GDM vs. NDM). The risk of intrauterine fetal death in pregnancies of diabetic women is still increased. It seems that especially the LGA fetuses of diabetic mothers and SGA fetuses of non-diabetic mothers are at greater risk of intrauterine death.

OP07.25: Hemoglobin concentration in SGA fetuses with abnormal umbilical artery Doppler delivered at &lt; 33 weeks' gestation

OP07.25: Hemoglobin concentration in SGA fetuses with abnormal umbilical artery Doppler delivered at &lt; 33 weeks' gestation

Predictive value of a single early fetal weight estimate in normal pregnancies

Objectives To evaluate the accuracy of ultrasound-based fetal weight estimates made at 28–34 weeks of gestation in predicting small- and large-for-gestational-age infants (SGA, LGA) at term. Methods Two-hundred and fifty-nine patients with a healthy, singleton pregnancy in whom fetal biometry measurements were routinely performed between 28 and 34 weeks’ gestation, were recruited at term delivery. The sonographic estimated fetal weight (EFW) and the birth weight were converted to percentiles on the basis of locally developed growth charts and compared. Multivariate linear stepwise regression analysis was used to predict the birth weight and birth weight percentile. The resulting equation (projectile formula) was used to determine the calculated birth weight, and that value was compared with the actual birth weight. The Bland and Altman plot and Passing and Bablok regression were used to compare between the calculated birth weight and the actual birth weight. Results Mean gestational age at ultrasound examination was 32 ± 1.6 weeks (28–34), and mean age at delivery was 39 ± 1.7 weeks (37–42). The multivariate correlation between the calculated birth weight and the birth weight ( R 2 = 0.524) was higher than the correlation between the sonographic EFW and the birth weight ( R 2 = 0.083). Both the sonographic EFW and the calculated birth weight are characterized by low positive predictive values in predicting SGA or LGA infants. The calculated birth weight was more accurate in excluding SGA and LGA infants (negative predictive values of 99.5% and 100%, respectively). On method comparison tests, the calculated birth weight was not significantly different than the actual birth weight. Conclusions Fetal weight estimation at the early third trimester poorly predicts the birth weight centile at term. It remains uncertain, however, if it would be useful to use the calculated birth weight in pregnancies with clinically suspected SGA or LGA fetuses.

Middle cerebral artery peak systolic velocity and ductus venosus pulsatility index – Which is best in predicting perinatal mortality of SGA fetuses with abnormal umbilical artery?

It has been suggested that abnormal ductus venosus (DV) pulsatility index (PI) is a better predictive parameter of adverse perinatal outcome than umbilical artery (UA) PI. Recently, it has been reported that middle cerebral artery (MCA) peak systolic velocity (PSV) predicts perinatal mortality better than MCA-PI. The aim of this study was to compare the performance of MCA-PSV and DV-PI in predicting perinatal mortality.

OC20.03: Middle cerebral artery peak systolic velocity—a new Doppler parameter in the evaluation of SGA fetuses with an abnormal umbilical artery

Fetal “brain sparing” is suspected in SGA fetuses when there is a low middle cerebral artery (MCA) pulsatility index (PI) value. It has been suggested that the MCA peak systolic velocity (PSV) is increased in a subset of SGA fetuses (UOG 1998; 12 : 39). The aims of this study were A) to determine if there is a relationship between MCA-PSV and perinatal mortality in preterm SGA fetuses, who have also an abnormal umbilical artery velocimetry, and B) to compare the performance of the MCA-PI and MCA-PSV in predicting perinatal mortality. The study population consisted of patients diagnosed to have SGA (EFW or AC < 10th percentile) and an abnormal UA velocimetry (PI outside the reference range or absent/reverse flow). Middle cerebral artery PSV and PI for each fetus were considered abnormal when they fell outside the reference range. Neonatal hemoglobin was determined at birth. Comparison of proportions was conducted using two-tailed Fisher's exact test. P < 0.05 was considered statistically significant. Among the 26 fetuses who met the inclusion criteria, gestational age at delivery ranged between 24 weeks and 32.5 weeks' gestation. The median interval between the last examination and delivery was 1 day. Twenty-two fetuses had an abnormal MCA-PI and 15 had an abnormal MCA-PSV. For a specific gestational age, fetuses with abnormal MCA-PSV values had a higher perinatal mortality than those with MCA-PSV values within the reference range [9/15 (60%) vs. 1/11 (9.1%); odds ratio (OR), 15; 95% CI, 1.5 to 149; P = 0.014]. In contrast, the perinatal mortality for fetuses with abnormal MCA-PI values was not significantly different from those with normal MCA-PI values [9/22 (40.9%) vs. 1/4 (25%); OR, 2; 95% CI, 0.18 to 23, P = 1]. None of the newborns in whom hemoglobin was determined had anemia (n = 18). 1) A high MCA-PSV in preterm SGA fetuses with an abnormal UA Doppler velocimetry is strongly associated with perinatal mortality; 2) a high MCA-PSV predicts perinatal mortality better than a low MCA-PI; 3) we speculate that the mechanism responsible for the increased MCA-PSV reflects an elevated blood pressure and increased blood flow; and 4) we propose that MCA-PSV may be valuable in the clinical assessment of SGA fetuses who have an abnormal UA velocimetry.

Fetal response to maternal exercise in pregnancies with uteroplacental vascular insufficiency

To determine the fetal response to sub-maximal maternal exercise at 22-26 weeks in pregnancies with abnormal uterine artery Doppler. A prospective matched cohort-control study was undertaken. Twelve singleton pregnancies with bilateral uterine artery notching and mean uterine pulsatility index (PI) values >1.45 at 22-26 weeks of gestation were evaluated. Matched controls (n = 23) were clinically normal and had normal uterine artery Doppler. Maternal and fetal cardiovascular responses to 5 minutes of steady state cycling at 10% and at 15% of maximum predicted work rate were evaluated by ultrasound/Doppler. Baseline characteristics were similar between the 2 groups. No differences in either resting or in exercise-induced maternal or fetal cardiac parameters were found between the 2 groups. There was no difference between the basline umbilical artery PI values for cases and controls but the difference became significant post exercise (P = .02 after the 10% load and P = .006 after the 15% load). Of the 12 cases, 6 subsequently developed preeclampsia, 5 had SGA fetuses, 2 of which developed absent end-diastolic flow velocity (AEDF) and early-onset intrauterine growth restriction (IUGR). Mean gestational age at delivery was 33 weeks vs. 40 weeks in the controls (P = .001). 3/12 (25%) cases developed transient (AEDF) in umbilical artery Doppler after the exercise that recovered after cessation of exercise, compared with none of the controls. 2/3 of these subsequently developed AEDF and IUGR. Sub-maximal steady state exercise may have transient deleterious effects in a subset of women with uteroplacental vascular insufficiency. These findings may impact on advice regarding physical activity in this sub-group of women. Dynamic testing such as maternal exercise may be of value in identifying pregnancies that adapt poorly to uteroplacental vascular insufficiency.

Fetal brain/liver volume ratio and umbilical volume flow parameters relative to normal and abnormal human development.

To estimate fetal brain volume from head circumference and published postmortem data; to determine normal values for the fetal brain/liver volume ratio relative to gestational age; to establish the relationship between the brain/liver volume ratio and fetal circulatory parameters during normal and restricted (SGA) fetal growth. This was a cross-sectional study involving a total of 47 uncomplicated pregnancies appropriate-for-gestational age (AGA) and 23 pregnancies resulting in the delivery of a SGA fetus. At enrollment gestational age ranged between 20 and 36 weeks in both groups. Umbilical venous cross-sectional area and time-averaged velocity for calculation of volume flow as well as velocity waveforms from the umbilical artery, middle cerebral artery and ductus venosus, were recorded. Fetal liver volume measurements were obtained using three-dimensional ultrasound. Fetal brain volume was estimated from fetal head volume following comparison with published postmortem data on fetal brain weight. A significant correlation was observed between prenatally estimated fetal head volume and postmortem fetal brain volume. Fetal brain volume was approximately half that of fetal head volume. The normal fetal brain/liver volume ratio demonstrated a significant reduction with gestational age (R = -0.54; P < 0.001). The normal mean +/- standard deviation (SD) fetal brain/liver volume ratio (3.4 +/- 0.7) was significantly different (P < 0.001) from the mean fetal brain/liver volume ratio in the SGA group (n = 23) (5.9 +/- 1.9). A significant difference existed for mean umbilical venous volume flow between AGA (104.7 +/- 26.9 mL/min/kg) and SGA (59.6 +/- 22.7 mL/min/kg) fetuses. In the SGA fetus, there was a significant inverse relationship (P < 0.001) between fetal weight-related umbilical venous volume flow and fetal brain/liver volume ratio. In a subset of 16 SGA and 16 AGA fetuses matched for gestational age, a significant difference existed for umbilical artery pulsatility index (2.30 +/- 1.52 vs. 0.99 +/- 0.19), fetal middle cerebral artery pulsatility index (1.3 +/- 0.4 vs. 2.1 +/- 0.3) and late diastolic flow velocity in the fetal ductus venosus (6.9 +/- 14.2 cm/s vs. 23.9 +/- 8.8 cm/s), but not for peak systolic, early diastolic and time-averaged velocity in the ductus venosus. Sonographic estimates of fetal brain volume can be obtained. The fetal brain/liver volume ratio is a predictor of fetal outcome in the growth-restricted fetus. An inverse relationship exists in SGA fetuses between brain/liver volume ratio and fetal weight-related umbilical venous blood flow.