The hemodynamic effects of maternal hypo- and hyperoxygenation in healthy term pregnancies

OBJECTIVE: To evaluate the hemodynamic effects of maternal hypo- and hyperoxygenation in normal term pregnancy. METHODS: Ten healthy women between 35-41 weeks' gestation were exposed to 10% oxygen in inspired air for 10 minutes and, after a 5-minute recovery period, to a stepwise increase in oxygenation with 50 and 100% oxygen for 10 minutes. Maternal ventilation, hemodynamics, and oxygenation were assessed noninvasively, and maternal and fetal vascular responses were assessed with pulsed-wave color Doppler velocimetry. Computerized cardiotocography was used for fetal heart rate (FHR) analysis. RESULTS: Substantial maternal hypoxia was achieved and accompanied by a statistically significant rise in the maternal heart rate (from 89 +/- 11 to 104 +/- 16 beats per minute) and systolic blood pressure (from 123 +/- 13 to 131 +/- 13 mmHg). Doppler measurements demonstrated a statistically significant decline in the pulsatility index (PI) of the maternal internal carotid artery (from 1.8 +/- 0.3 to 1.5 +/- 0.4) and an increase in the uterine artery PI (from 0.60 +/- 0.12 to 0.72 +/- 0.13). Baseline FHR, heart rate variability, and Doppler velocimetry in the umbilical artery and the middle cerebral artery showed no statistically significant changes. Hyperoxia did not cause changes in the maternal circulation, but the FHR decreased significantly (from 142 +/- 12 to 133 +/- 11 beats per minute). CONCLUSION: Acute short-term hypoxia modifies the maternal circulation, suggesting redistribution of maternal blood flow, but exerts no detectable effects on the healthy fetus. Maternal hyperoxygenation induces no apparent adverse effects.     

Experimentally contaminated reabsorbable meshes: their evolution in abdominal wall defects

The effect of maternal hyperglycemia on fetal regional circulation in appropriate for gestational age and small for gestational age fetuses was evaluated. Color Doppler flow imaging and pulsed Doppler ultrasonographic assessments were made on 15 appropriate for gestational age and 19 small for gestational age fetuses, ranging from 33 to 40 weeks' gestation before, 60 minutes, and 120 minutes after a maternal 75 g glucose load. The pulsatility index (PI) was calculated for middle cerebral artery, descending aorta, splenic artery, renal artery, femoral artery, and umbilical artery. Simultaneously, maternal plasma glucose concentration was measured. Baseline PI value (1.50 +/- 0.31) for middle cerebral artery in small for gestational age fetuses was significantly lower than that (1.89 +/- 0.37) in appropriate for gestational age fetuses (p < 0.05); however, there were no significant differences in baseline PI values for other arteries in both groups. In appropriate for gestational age fetuses, the mean PI decreased from 1.89 +/- 0.37 to 1.47 +/- 0.33 at 60 minutes, and to 1.55 +/- 0.32 at 120 minutes (p < 0.05), but no changes were found in the other arteries. In small for gestational age fetuses, there was no significant change in PI value for each artery before and after maternal glucose load. Maternal hyperglycemia induces a significant decrease in cerebrovascular resistance in appropriate for gestational age fetuses but not in small for gestational age fetuses. These results provide a foundation for evaluating the effect of maternal hyperglycemia on fetal regional circulation.     

Successful medical management of isolated renal zygomycosis: case report and review

OBJECTIVE: Determination of gestational age-related fluctuations in heart rate in the umbilical artery of the early human fetus. METHODS: Doppler velocity recordings from human umbilical artery were obtained, in a cross-sectional study design in 137 singleton pregnancies at 10-20 weeks of gestation. After exclusion criteria were applied, data on 117 normal pregnancies were available and subdivided into group I: 10-12 weeks (n = 49); group II: 13-16 weeks (n = 43); and group III: 17-20 weeks (n = 25). Blood flow velocity waveforms were reconstructed from Doppler audio signals. Variability in heart rate was calculated using Fast Fourier Transforms (FFT). Individual heart rate variability power spectra were subdivided into frequency bands. RESULTS: Fetal heart rate variability decreases at 10-20 weeks and demonstrates a shift to lower frequencies at 17-20 weeks. CONCLUSIONS: Fetal heart rate variability is related to gestational age and shows a shift to lower frequencies which may reflect autonomic functional development.     

Color Doppler ultrasound of uterine, fetoplacental and fetal blood vessels in the 2nd trimester in normal pregnancies

We investigated 69 healthy women with normal pregnancy and delivery in order to establish normal values for the second trimester of gestation. In a cross-sectional study we measured the pulsatility index (PI), the maximal systolic velocity (V-MAX) and the mean velocity (V-MEAN) in the uterine arteries (UAA), the umbilical artery (UA), the fetal thoracic aorta (FTA) and the middle cerebral artery (MCA) from the 14th to the 24th week of gestation. A regression analysis shows a significant slope of the PI of UAA and UA (p < 0.01), whereas in contrast to the UA there is no significant difference of the median values of the UAA-PI from the 18th week of gestation. With progressive gestation V-MEAN of UAA increases more (p < 0.001) than V-MAX (p < 0.05) as a result of the increasing diastolic blood flow. In the UA there is also a significant rising trend of V-MAX and V-MEAN (p < 0.0001). No significant changes of the PI of FTA and MCA are seen, although there is a slight increasing trend. After the 20th week in the MCA a marked tendency to high PI-values is observed, whereas there is a change between different flowpatterns prior to the 20th week. V-MAX and V-MEAN of FTA increases significantly, but there is no change in the MCA. Our results for UAA and UA correspond to the known morphologic changes in the utero- and fetoplacental vessels in the second trimester and are comparable to other results. Particularly the physiology of the cerebral perfusion needs to be investigated more intensively. These normal values provide a good basis for early and complex assessment of a disturbed perfusion in the second trimester.     

The influence of the maternal heart rate on the uterine artery pulsatility index in the pregnant ewe

We investigated the influence of the maternal heart rate on the uterine artery pulsatility index in pregnant ewes. We used an external pacemaker to alter the heart rate of 5 pregnant ewes at 16-17 weeks of pregnancy and examined the effect of changes in the maternal heart rate on the uterine artery flow velocity waveforms and the pulsatility index, as determined by Doppler velocimetry. The uterine artery pulsatility index showed a significant negative correlation with the maternal heart rate. There were no significant changes in other hemodynamic parameters. The maternal heart rate had a significant influence on the uterine artery pulsatility index.     

The response regulator-like protein Pos9/Skn7 of Saccharomyces cerevisiae is involved in oxidative stress resistance

To assess the standard curves of pulsatility index (PI) in different segments of middle cerebral artery (MCA): initial segment (MI) and subcortical segment (M2); to determine the variation of the flow velocity waveforms (FVW) of the M1 and M2 segments of MCA in presence of fetal distress and to establish the possible correlation between the two segments of MCA. 50 normal pregnancies from 25 weeks of gestation to term and 20 pregnancy with alteration of fetal growth rate were investigated with serial records of the FVW of the M1 and M2 segments of the MCA and of the umbilical artery (UA) with a colour Doppler system. Severe fetal distress was associated to cerebral-placental ratio below 1 (C/P < 1). The perinatal outcome was established on the basis: 1) abnormal intrapartum CTG, 2) emergency cesarean section, 3) Apgar score at 1st and 5th minute after birth and 4) birth eight centiles. In normal pregnancy P1 of M2 was always higher than that of M1: therefore M2/M2 resulted below 1, with a maximum peak near 32 weeks of gestation. In presence of moderate fetal distress only P1 of M2 was reduced (M1/M2 > 1). It exists a significant difference of PI in M1 and M2 segments of fetal MCA during gestation: thus MCA so it is important to identify the tract of fetal MCA when recording its FVW. Moreover we suppose that an initial "cerebral sparing" effect exists in order to protect the cortex by the initial hypoxic injury: this is shown by a M1/M2 > 1. The progression of fetal distress results in a greater haemodynamic modification, the so called "brain sparing" which is usually present when C/P < 1.     

Effect of dehydroepiandrosterone sulfate on uterine artery flow velocity waveforms in term pregnancy

OBJECTIVE: To investigate the interrelation between estrogen synthesis by the fetoplacental unit and uteroplacental hemodynamics in term pregnancy. METHODS: Transvaginal color Doppler flow imaging and pulsed Doppler ultrasonographic assessments were made on ten normal full-term pregnant women before and 3, 5, 10, 30, and 60 minutes after the administration of a 200-mg intravenous dose of dehydroepiandrosterone sulfate (DHAS) in 20 mL of 5% dextrose. Ten normal full-term pregnant women received 20 mL of 5% dextrose as controls. The pulsatility index (PI) values for the uterine artery, heart rate, and mean arterial pressure were recorded. Plasma estradiol (E2) was measured before and 10 minutes after the infusion. RESULTS: In the DHAS group, uterine artery PI decreased from baseline by 26% (P < .05) after 5 minutes, and the mean reduction was 36% (P < .05) after 10 minutes and 15% (P < .05) after 30 minutes. The PI returned to the baseline value 60 minutes later. In the control group, there was no change in uterine artery PI. No change was found in heart rate or mean arterial blood pressure in the control or DHAS groups. The mean plasma E2 increased from 22.3 +/- 6.6 to 56.2 +/- 24.1 ng/mL (P < .05) 10 minutes after the infusion in DHAS subjects, whereas there was no significant change in plasma E2 in the controls. CONCLUSION: Dehydroepiandrosterone sulfate induces a significant decrease in the uterine artery PI, which suggests a possible decrease in uterine vascular impedance in term pregnancy.     

Effect of antenatal administration of thyrotrophin releasing hormone on fetal flow velocity waveforms

AIM: To determine whether antenatal administration of thyrotrophin releasing hormone (TRH), to promote lung maturation, alters blood flow through the fetal middle cerebral, umbilical artery, or ductus arteriosus and through the maternal uterine arteries. METHODS: The effect of transplacentally administered TRH on the fetal circulation was prospectively evaluated in 30 patients between 24 and 34 weeks' gestation. TRH (400 micrograms) was given to the mother intravenously either as a bolus or an infusion. Fetal effects were determined by measuring the maximum velocity and pulsatility index (PI) in middle cerebral artery, ductus arteriosus, uterine artery and umbilical artery Doppler waveforms. Measurements were made immediately before, and 10 and 60 minutes after maternal TRH administration. RESULTS: Intravenous injection of TRH had no significant effect on PI in the uterine, umbilical, or middle cerebral artery and the ductus arteriosus within 60 minutes of administration in either group. CONCLUSION: The antenatal use of TRH in conjunction with steroids for fetal lung maturity does not affect utero-placental or fetal haemodynamic variables, as measured by Doppler. These findings, therefore, do not support the suggestion that antenatal intravenous administration of TRH either as bolus or infusion may have immediate adverse vascular effects in the fetus.     

Maternal and fetal nitric oxide synthesis is decreased in pregnancies with small for gestational age infants

Our purpose was to evaluate whether maternal and fetal nitric oxide synthesis in pregnancies with small for gestational age (SGA) infants are different from those in pregnancies with appropriate for gestational age (AGA) infants. Maternal and fetal circulating nitrate and nitrite concentrations were compared between 30 pregnancies with AGA and 10 pregnancies with SGA at birth. End-products of nitric oxide synthesis were measured in maternal and cord venous blood samples using a fluorometric assay. Umbilical artery blood pH and PO2 were also measured. Maternal circulating nitrite and nitrate concentrations (6.91 +/- 1.27 microM) in pregnancies with SGA were significantly lower than those (11.69 +/- 1.33 microM) in pregnancies with AGA (P = 0.015). Fetal circulating nitrite and nitrate concentrations (7.54 +/- 1.09 microM) in pregnancies with SGA were also significantly lower than those (11.24 +/- 1.08 microM) in pregnancies with AGA (P = 0.024). There were no significant differences in umbilical artery blood pH and PO2 between the two groups. These results suggest that maternal and fetal nitric oxide synthesis are decreased in pregnancies with SGA infants.     

Use of colour and spectral Doppler ultrasound examination in gynaecology

Objective: To review and sum up the published literature on gynecological Doppler ultrasound examination. Methods: Publications on gynecological Doppler ultrasound examination already known by the author, publications found in the bibliographic database Medline, and publications found in the reference lists of available studies were read, and relevant information was extracted and summarized. Results: Reference data representative of normal findings at transvaginal color and spectral Doppler ultrasound examination of the uterine and ovarian arteries have been established in healthy pre- and post-menopausal women and in normal early pregnancies. Blood flow velocities in the uterine and ovarian arteries change during the normal menstrual cycle and are very different in pre- and post-menopausal women. Lower blood flow velocities and higher pulsatility index (PI) values have been recorded in the ovarian arteries after the menopause. Uterine artery blood flow velocities increase and uterine artery PI values and resistance index (RI) values decrease with gestational age in the first trimester. There is not yet an established role of the gynecological Doppler ultrasound examination in clinical practice. It remains unclear whether the gynecological Doppler ultrasound examination contributes substantially to the clinical management of early pregnancy complications or infertility problems, to the differential diagnosis of pelvic masses or uterine pathology. Conclusions: Large prospective studies-preferably randomized controled trials-are needed to determine the clinical value of the gynecological Doppler ultrasound examination. Copyright 1997 Elsevier Science Ireland Ltd.     

Maternal and uteroplacental haemodynamic state in pre-eclamptic patients during spinal anaesthesia for Caesarean section

We have studied the effects of crystalloid (Ringer's acetate 1 litre) preloading and subsequent spinal anaesthesia in 12 pre-eclamptic parturient patients undergoing elective Caesarean section. Maternal placental uterine artery circulation was measured using a pulsed colour Doppler technique with simultaneous measurement of maternal haemodynamic state. Despite preloading, mean maternal systolic arterial pressure (SAP) decreased significantly and marked maternal hypotension (SAP < 80% of baseline value) was recorded in two patients after induction of spinal anaesthesia. Mean central venous pressure increased significantly after preload, but decreased to baseline shortly after induction of spinal anaesthesia. Mean pulsatility index (PI) in the uterine artery did not change during preload or spinal block. In one patient, uterine artery PI increased significantly when SAP decreased to 71% of the baseline value, 14 min after induction of spinal anaesthesia. These results suggest that preload with crystalloid solution does not prevent maternal hypotension in pre-eclamptic patients, and that changes in uterine artery velocity waveforms were minor when SAP was 80% or more of baseline during spinal anaesthesia. These changes did not appear to have any major effect on the clinical condition of the neonate, as assessed by Apgar score and umbilical artery pH values.     

Gait patterns in children with hemiplegic spastic cerebral palsy

Our objective was to study uterine and umbilical artery flow resistance during the oxytocin challenge test (OCT). The study population was 21 women with suspected placental insufficiency; one woman was excluded because of a positive OCT with reactive fetal heart rate pattern. We carried out simultaneous electronic fetal heart rate monitoring and Doppler velocimetry of uterine and umbilical artery flow during the OCT. The uterine artery flow resistance increased significantly during contractions in both OCT-positive (n = 5) and OCT-negative (n = 15) cases compared with basal values, but the increase was significantly higher in positive cases. The umbilical artery flow resistance increased significantly during contractions in OCT-positive cases, but was almost unchanged in negative cases. During uterine inactivity, there were no differences between the groups for any vessel. This study showed that fetal heart rate decelerations during the OCT are associated with rapid and exaggerated increases of vascular resistance in both uterine and umbilical arteries. The causal relationship is unknown, but the findings indicate pathophysiological mechanisms revealed only during uterine contractions.     

Effect of dehydroepiandrosterone sulfate on fetal middle cerebral artery flow velocity waveforms in term pregnancy

OBJECTIVE: To investigate whether bolus injection of dehydroepiandrosterone sulfate (DHAS) is associated with changes in fetal middle cerebral artery flow velocity waveforms in term pregnancy. METHODS: Ten normal full-term pregnant women received the administration of a 200-mg intravenous dose of DHAS in 20 ml of 5% dextrose. Ten normal full term pregnant women received 20 ml 5% dextrose as controls. Color Doppler flow imaging and pulsed Doppler ultrasonographic assessments were made on fetuses in each group before and 10 min, 30 min, 60 min, 90 min. and 120 min after DHAS or dextrose administration. The pulsatility index (PI) values for the middle cerebral artery, and umbilical artery, and fetal heart rate were recorded. RESULTS: In the DHAS group, middle cerebral artery PI decreased from baseline by 24% (p<.05) after 10 min, and the mean reduction was 22% (p<.05) after 30 min. The PI returned to the baseline value 60 min later. In the control group, there was no change in middle cerebral artery PI. No change was found in umbilical artery PI or fetal heart rate in the control or DHAS group. CONCLUSION: DHAS induces a significant decrease in the fetal middle cerebral artery PI, which suggests a possible decrease in fetal cerebral vascular impedance in term pregnancy.     

Ultrasonographic and hormonal monitoring of pregnancy in the saddle back tamarin, Saguinus fuscicollis

Ultrasonography was used in six saddle back tamarin females (Saguinus fuscicollis) to diagnose pregnancy, monitor the patterns of uterine growth and embryonic/foetal development and examine the incidence loss of single embryos/foetuses. Pregnancy was reliably diagnosed 17 days after conception, 10 days earlier than by plasma progesterone measurement. The patterns of uterine and embryonic/foetal growth paralleled those reported for the common marmoset, including a delay in embryonic development. The results support the hypothesis of retardation of organogenesis in most callitrichid species. Individual embryos could be reliably identified from day 50 of pregnancy; a loss of single embryos/foetuses after this stage did not occur. All pregnancies were carried to term, resulting in five times twins and one singleton. The smaller litter size compared to the common marmoset may be due to loss of single embryos at earlier stages of pregnancy or to a lower ovulation rate.     

Transcranial assessment of maternal cerebral blood flow velocity in patients with pre-eclampsia

BACKGROUND: To clarify the cerebral hemodynamics in pre-eclamptic pregnant women, we investigated the blood flow velocity of the cerebral arteries. METHODS: The mean blood flow velocity and pulsatility index (PI) of the middle cerebral artery (MCA) and internal carotid artery (ICA) in normal pregnant women (n = 35) and pre-eclamptic patients (n = 18) were examined transcranially using pulsed-wave Doppler technique with a 2 MHz probe. In two pre-eclamptic women with post-partum visual disturbance, we examined the mean blood flow velocity and PI of the MCA and ICA every day. RESULTS: The mean blood flow velocity of the MCA in the pre-eclamptic patients (89.7 +/- 20.5 cm/s) was significantly higher than that in the normal pregnant women (53.6 +/- 16.9 cm/s) (p < 0.05). PI of the MCA in the former group (0.67 +/- 0.13) was significantly lower than that in the latter (0.78 +/- 0.02) (p < 0.05). There was no significant difference between these two groups in these variables of the ICA. In the two patients with visual disturbance, the mean blood flow velocity of the MCA was increased before the onset of visual disturbance and decreased gradually following the disappearance of this symptom. In these patients, spasm of the MCA was confirmed by magnetic resonance angiography. CONCLUSIONS: In pre-eclamptic patients, we found increased MCA mean velocity before the onset of visual disturbance. Transcranial Doppler may be useful for the evaluation of cerebral hemodynamics and the prediction of eclampsia.     

Abnormal patterns of mucin secretion in ileal neobladder mucosa: evidence of preneoplastic lesion?

We used transcranial Doppler (TCD) to investigate whether there are cerebral circulation differences between young and elderly subjects in response to postprandial postural changes. Preprandial and postprandial systolic and diastolic blood pressure, heart rate, mean middle cerebral artery (MCA) velocity (Vmean MCA), systolic/diastolic MCA velocity ratio (Vs/Vd MCA) and pulsatility index (PI) were determined in 15 healthy elderly subjects (mean age 74.3 +/- 6.5 years) and in 10 younger subjects (mean age 31.6 +/- 7. 2 years) in the supine position and after a postural change. As compared with young subjects, elderly ones showed a greater postprandial systolic pressure decline (p < 0.05) associated with a significant decrease of Vmean MCA (p < 0.05), and a greater increase of Vs/Vd and PI (p < 0.05 both). We conclude that, as compared with young subjects, elderly ones have reduced cerebrovascular adaptive response to pressure modifications induced by postprandial postural changes.     

Cholera toxin acts as a potent adjuvant for the induction of cytotoxic T-lymphocyte responses with non-replicating antigens

OBJECTIVE: To evaluate the relation between the development of the uteroplacental circulation as assessed by Doppler velocimetry and the maternal blood relaxin concentration. METHODS: Transvaginal color Doppler investigation of the uteroplacental circulation was performed in 42 healthy women at 6-15 weeks' gestation before termination of pregnancy for psychosocial reasons. The resistance index (RI), pulsatility index (PI), and maximum peak velocity were recorded at the level of the main uterine artery, and the presence of intervillous flow was noted. Relaxin, hCG, 17 beta-estradiol (E2), and progesterone levels were measured in maternal venous blood. RESULTS: Limited intervillous flow was noted from 10 weeks' gestation and continuous intervillous flow from 12 weeks. An inverse relation was observed between the circulating levels of both E2 and progesterone and uterine artery RI and PI, whereas the relaxin level correlated positively with uterine RI and PI. Estradiol and progesterone levels also correlated positively with uterine peak systolic velocity and intervillous blood flow. Multiple linear regression analysis indicated that both hormones contributed to the decrease in downstream resistance to uterine blood flow with advancing gestational age, as assessed by uterine RI. In addition, relaxin contributed to the uterine RI and PI and to the intervillous blood flow. CONCLUSION: These data suggest that relaxin, E2, and progesterone may influence the changes in uterine blood flow that occur in early pregnancy. The role played by E2 and progesterone in the development of the uteroplacental circulation may be modulated by relaxin, constituting a novel function for this ovarian peptide.     

Premenstrual dysphoric disorder: controversies surrounding the diagnosis

OBJECTIVE: To evaluate the umbilical and uterine arterial Doppler flow velocity waveform systolic to diastolic (S/D) ratios performed at 24-30 weeks gestation for predicting fetal growth retardation (IUGR). METHODS: A prospective double blind study was conducted in 118 cases of high risk singleton pregnant women. The umbilical and uterine arterial S/D ratios were measured at 24-30 gestational weeks and the pregnancy outcomes were followed up. RESULTS: The prevalence of IUGR in our study population was 16.9%. At 24-30 weeks gestation, the S/D ratio of both umbilical artery and uterine artery in IUGR pregnant women were significantly higher than those in normal pregnant women, while the fetal biometric measurements were normal in all the 118 cases. The sensitivity, specificity and positive predictive value of umbilical arterial S/D ratio to predict IUGR were 80.0%, 83.7% and 50.0% with a Kappa index of 0.51 at 24-30 weeks gestation. With lower sensitivity, specificity, positive predictive value and Kappa index (40.0%, 84.5%, 34.8% and 0.23 respectively), the uterine arterial S/D ratio had less predictive value. CONCLUSIONS: The umbilical arterial Doppler flow velocity waveform S/D ratio may be an earlier predictor for screening of IUGR at 24-30 weeks gestation in high risk pregnant women with normal fetal biometric measurements.     

Value of intraplacental villous artery Doppler measurements in severe preeclampsia

Blood flow velocity waveforms were recorded by color Doppler ultrasound from intraplacental villous and umbilical arteries in 20 normal and 23 severe preeclamptic pregnancies. The results of the resistance index measurements in intraplacental villous arteries were 0.51 +/- 0.037 and 0.55 +/- 0.052 in healthy controls and preeclamptics respectively, which was not significantly different. Resistance indices showed a decrease through the umbilical cord from fetus to placenta in both groups. We also noted that Doppler examination of the umbilical cord might be an early indicator of fetal compromise. Detectable intraplacental villous flows were in normal limits even in patients with abnormally high umbilical resistance indices and failure to detect villous artery color Doppler flow signals is probably associated with fetal compromise. We conclude that Doppler measurements from the intraplacental arteries cannot be used in clinical management of patients with severe preeclampsia.     

The head-to-abdomen circumference ratio: a reappraisal

Our objective was to assess the clinical significance of the sonographically derived head-to-abdomen circumference ratio in small-for-gestational-age (SGA) fetuses. The head-to-abdomen ratio was determined in 134 singleton SGA fetuses without ultrasound evidence of malformations at 26-40 weeks' gestation. Data were collected regarding antenatal surveillance, umbilical artery Doppler velocimetry and neonatal outcome. In SGA fetuses, the head-to-abdomen ratio, adjusted for gestational age, had a normal frequency distribution, positively skewed with regard to fetuses with normal birth weight. An elevated head-to-abdomen ratio was found in 56 SGA fetuses (42%), and was associated with increased perinatal mortality (odds ratio 3.27; 95% confidence internal 1.04-9.34), lower birth weight (1533 +/- 635 g vs. 2022 +/- 655 g, p < 0.0001) and lower gestational age at delivery (34 +/- 3.6 weeks vs. 36.3 +/- 3.6 weeks, p < 0.005). However, logistic regression revealed that the most powerful antenatal determinants of pregnancy outcome were Doppler velocimetry of the umbilical artery, followed by biophysical profile, while no independent correlation was found with the head-to-abdomen ratio. The existence of two distinct categories of SGA fetuses, 'symmetric' and 'asymmetric', remains uncertain. An elevated head-to-abdomen ratio is an adverse risk factor for pregnancy outcome. However, this parameter has no clearcut clinical value when umbilical artery Doppler velocimetry and biophysical antenatal testing are available.