Reference ranges for blood pressure in preschool Australians, obtained by oscillometry

OBJECTIVE

To derive reference centiles for blood pressure in children aged 1-6 years which seek to address shortcomings in available reference ranges.

METHODS

Prospective cohort study of 2876 children in Perth, Western Australia, commenced in 1989 with serial blood pressure measurements through early childhood obtained by oscillometry under standardized conditions.

RESULTS

Gender-specific reference centile charts for systolic and diastolic blood pressure, (i) across ages 1-6 years and (ii) across the range of corrected Body Mass Index values at ages 1, 3 and 6 years, were generated by fitting linear models with both fixed and random effects.

CONCLUSIONS

Reference values for blood pressure for young children are of clinical use and may be of long-term predictive value.

Effect of corticosteroids on brain growth in fetal sheep

OBJECTIVE

To compare the effects of single and repeated courses of corticosteroids on brain growth in fetal sheep.

METHODS

Pregnant sheep were given intramuscular betamethasone (0.5 mg/kg) at 104 days' gestation followed at 111, 118, and 124 days by equivalent volumes of sterile normal saline (n = 12) or betamethasone (n = 12). Controls received equivalent volumes of sterile normal saline at all four intervals (n = 12). Lambs were delivered at 125 (preterm) or 145 (term) days. After perfusion, we measured weights (grams) for whole brain, cerebrum, cerebellum, and brain stem, volumes (milliliters) for whole brain and cerebrum, and maximum cerebral anterior-posterior length, width, and depth (centimeters).

RESULTS

In the single-injection group at preterm, there were no significant differences (P = .070) in whole-brain weight between the corticosteroid-treated animals (38.0 +/- 1.81 g) and controls (42.5 +/- 1.65 g). Cerebral length and depth were significantly reduced in the corticosteroid group (P < .05); other measures were not significantly different. At term, whole-brain weight was significantly lower (47.5 +/- 1.70 g; P = .022) compared with controls (53.4 +/- 1.73 g). All other measures were significantly reduced (P < .05) except cerebral and brain-stem weights and cerebral length. In the group that received repeated injections at preterm, whole-brain weight was significantly reduced (35.5 +/- 1.65 g; P = .005) compared with controls (42.5 +/- 1.65 g). All other measures were significantly reduced (P < .05) except cerebellar and brain-stem weights. At term, whole-brain weight was also significantly reduced (42.4 +/- 1.52 g; P = .001) compared with controls (53.4 +/- 1.73 g) as were all other measures (P < .05).

CONCLUSION

Administration of single and repeated courses of corticosteroids to pregnant sheep retarded fetal brain growth.

Pregnancy loss rates following second trimester genetic amniocentesis

Data from 3,953 consecutive second trimester genetic amniocenteses were analysed to determine pregnancy loss rates up to 6 weeks after the procedure. Information was prospectively collected on a cohort of 3,685 women in 3,896 singleton and 50 twin pregnancies, from 2 operating sites in Perth, Western Australia, using 9 operators over the 6-year period, 1989 to 1995. Complete information regarding pregnancy outcome was obtained for 3,643 of the 3,685 women (98.9%). There were 27 identified singletons and 1 set of twins lost within 6 weeks following amniocentesis. The overall pregnancy loss rate in this cohort was 29 of 3,911 (0.74%). The pregnancy loss rate associated with genetic amniocentesis is not excessive in comparison to the calculated background pregnancy loss rate of 1%, and it is suggested that each prenatal diagnostic team should determine their own complication rates for the purpose of counselling prior to amniocentesis.

Maternal, but not fetal, administration of corticosteroids restricts fetal growth

OBJECTIVE

Previous studies have shown that repeated doses of corticosteroids given to pregnant sheep improve postnatal lung function, but restrict fetal growth. Repeated administration of corticosteroids directly to the fetus also enhances postnatal lung function. The purpose of the present study was to investigate and characterize the relative effects on growth of repeated maternal and fetal treatments by study of body, organ, and placental weights.

METHODS

Date-bred pregnant sheep were given intramuscular betamethasone or saline to either the mother or fetus on three occasions at weekly intervals commencing at 104 days gestation, followed by cesarean section at 125 days. Twenty-two animals which had received three doses of betamethasone were compared with 21 which had received a single dose at 104 days and with 12 saline-treated controls.

RESULTS

Repeated maternal doses of betamethasone resulted in reductions in birthweight and weights of the placenta and major organs. Direct fetal injection did not affect birthweight, placental weight, placental/ birthweight ratio, or weights of the major organs with the exception of the liver.

CONCLUSIONS

Administration of repeated doses of betamethasone directly to the sheep fetus does not produce the growth-restricting effects induced by maternal administration and does not affect the placental/birthweight ratio.

Repeated antenatal corticosteroids: size at birth and subsequent development

OBJECTIVE

The objective was to study the effects of repeated antenatal corticosteroids on birth size, growth, and development in preterm infants.

STUDY DESIGN

This observational study followed up for 3 years a prospective geographic cohort in the state of Western Australia of 477 singleton infants born at <33 weeks' gestation.

RESULTS

Birth weight ratio decreased with increasing number of corticosteroid courses (P =.001), and multivariate analyses confirmed a reduction in birth weight of as much as 9% (P =.014) and a reduction in head circumference of as much as 4% (P =.0024). There were no additional benefits in mortality or respiratory outcomes, and there was a trend toward more severe chronic lung disease. At age 3 years growth and severe disability outcomes did not appear to be related to increasing number of corticosteroid courses.

CONCLUSIONS

In this cohort study repeated corticosteroid courses were associated with adverse effects on size at birth without apparent benefits. These changes have the potential to affect later development.

Placental implantation at 18 weeks and migration throughout pregnancy

BACKGROUND

We wanted to find the most frequent site of placental implantation at 18 weeks' gestation and placental migration during gestation.

METHODS

Placental location was identified in 2,526 singleton pregnancies at 18 weeks' gestation and characterized into nine groups. Placental migration in 1,336 of these pregnancies was assessed by serial ultrasonography.

RESULTS

At 18 weeks' gestation, posterior, high placental implantation was more common (45.1%) than anterior, high implantation (42.1%). Relocation of posterior, high placentas farther fundally (16.9%) was three times more likely than farther fundal migration of anterior, high placentas (4%).

CONCLUSIONS

Posterior fundal placental implantation is more common at 18 weeks' gestation than anterior implantation. Posteriorly implanted placentas are more likely than anterior placentas to migrate farther fundally during gestation. The greater relocation of posterior placentas farther fundally suggests a greater growth of posterior versus anterior uterine wall smooth muscle.

Ultrasound features of congenital listeriosis--a case report

We present a case of congenital listeriosis in a twin pregnancy. Presentation was prompted by decreased fetal movements and an ultrasound examination which demonstrated features similar to those observed in an adult with inflammatory conditions of the bowel, namely, small amounts of ascites, dilated loops of bowel and thickening of the bowel wall. Such ultrasound signs may be useful in consideration of the diagnosis of congenital infection and prompt diagnostic tests and appropriate interventions that assist in early therapy.

Fetal growth retardation, particularly within lymphoid organs, following repeated maternal injections of betamethasone in sheep

OBJECTIVE

To examine the effect of single or repeated injections of maternally administered corticosteroids on fetal growth in sheep.

METHODS

Forty-six date-mated singleton gestation ewes were allocated at random to one of 3 groups: a single, or repeated injections of betamethasone, or a control group which received saline. On days 125 (preterm) or 145 (term) caesarean section delivery was performed. After lambs were killed, measures of size and weight were recorded. Data were analysed using Fishers Exact test and the Student's t-test.

RESULTS

Significant betamethasone dose dependent reductions in body and organ weights and biometry were found at preterm and term gestational ages (p < 0.05). There was little catch up growth in those in whom delivery was delayed until term. Thymus, spleen and liver were particularly targeted.

CONCLUSION

Repeated injections of betamethasone to the pregnant ewe cause significant reductions in fetal growth with little evidence of catch up by term. The effect of repeated maternal injections of corticosteroids in human pregnancy will await the results of randomized controlled trails.

Use of corticosteroids by Australian obstetricians--a survey of clinical practice

All Fellows, Members and trainees of the Royal Australian College of Obstetricians and Gynaecologists resident in Australia (n= 1,281) received a questionnaire relating to their practice of prescribing antenatal corticosteroids. 833 (65%) responded. The key findings were that 97% of Australian obstetricians prescribe antenatal corticosteroids in the classical setting of uncomplicated early preterm labour and 85% prescribe repeated courses in those cases in which the risk of preterm birth persists or recurs; 50% of obstetricians prescribe this agent weekly in cases with persisting risk of preterm birth. Some of the prescribing practices were found to be related to the number of years since obtaining specialist qualification. In view of the widespread clinical use of repeated doses of corticosteroids revealed in this present survey, it is clear that further research is warranted to determine the possible benefits and hazards of repeated exposures of the developing fetus to this therapy.

Repeated prenatal corticosteroids delay myelination in the ovine central nervous system

Maternal administration of corticosteroids is used to promote lung maturation in human infants considered at risk of preterm delivery [1]. Randomised trials of a single course of corticosteroid treatment have indicated no adverse long-term neurological or cognitive sequelae [2-5]. However, the current trend in many obstetric centres is to use repeated courses in cases where preterm birth has not eventuated, but the risk persists 7 days beyond administration of the original course [6-7]. This practice has not yet been subject to randomised trials of outcome. We have examined the effect of repeated injections of corticosteroids on the development of the optic nerve in prenatal fetal sheep and report a significant delay in the myelination of optic axons. Our results, together with those from other animal studies [8], show that repeated courses of corticosteroids may be detrimental to central nervous system (CNS) development. Clinical practice should balance the known beneficial effects on lung maturation of a single course of corticosteroid against the potential damage to the CNS of repeated courses.

Factors influencing the selection of analgesia in spontaneously labouring nulliparous women at term

We investigated the maternal characteristics, labour performance and delivery mode of 497 nulliparas entering labour spontaneously at term to identify the obstetric factors which influenced their choice of analgesia; 51.7% of these women used epidural analgesia. They were shorter (163 versus 165 cm, p = 0.002) and the mean gestation was 3 days greater than those not using epidural analgesia (40.2 versus 39.6 weeks, p = 0.0007). Median birth-weight in the epidural group was greater by 155 g (3,450 versus 3,295 gs, p = 0.0001). Analysis of the labour characteristics showed a lesser cervical dilatation on admission, significantly longer latent and active phases of labour and second stage length in the epidural cohort. The need for oxytocin augmentation was significantly greater in the epidural group, both prior to and after insertion. Oxytocin augmentation was strongly associated with an increased risk of operative intervention regardless of analgesia. Selection of intrapartum analgesia is not a random event and epidural analgesia appears to be an indicator of abnormal labour patterns. To further investigate the impact of analgesic methods on nulliparous labour we are currently conducting a prospective randomized controlled trial.

Prospective cohort study of factors influencing the relative weights of the placenta and the newborn infant

OBJECTIVES

To determine the demographic, environmental, and medical factors that influence the relative weights of the newborn infant and the placenta and compare this ratio with other factors known to predispose to adult ill health.

DESIGN

Prospective cohort study.

SETTING

The tertiary referral centre for perinatal care in Perth, Western Australia.

SUBJECTS

2507 pregnant women who delivered a single live infant at term.

MAIN OUTCOME MEASURES

Placental weight, birth weight, and the ratio of placental weight to birth weight.

RESULTS

By multiple regression analysis the placental weight to birthweight ratio was significantly and positively associated with gestational age, female sex, Asian parentage, increasing maternal body mass index, increased maternal weight at booking, lower socioeconomic status, maternal anaemia, and increasing number of cigarettes smoked daily. There were no consistent relations between the placental weight to birthweight ratio and measures of newborn size.

CONCLUSIONS

The ratio of placental weight to birth weight is not an accurate marker of fetal growth. In its role as a predictor of adult disease the ratio may be acting as a surrogate for other factors which are already known to influence health and may act before or after birth. Determining the role that relative growth rates of the fetus and placenta have in predisposing to adult disease requires prospective study to account for the many confounding variables which complicate this hypothesis.

Employment, exertion, and pregnancy outcome: assessment by kilocalories expended each day

OBJECTIVE

Our purpose was to evaluate the influence of employment and physical exertion on pregnancy outcome as quantified by kilocalories expended each day.

STUDY DESIGN

This prospective study assessed 2743 pregnant women who received prenatal care and were delivered at the major perinatal center in Western Australia between May 1989 and November 1991. All women completed an extensive questionnaire on their social, medical, psychosocial, and economic circumstances. The women were allocated to five groups on the basis of kilocalorie expenditure per day.

RESULTS

The characteristics of women in each energy expenditure group were different, with those in the least-expenditure group being younger and shorter, more likely to be living in worse socioeconomic conditions, smoke cigarettes, be nulliparous, and to be of an ethnic group other than white. After confounding effects were adjusted, women in the medium energy expenditure group were delivered of babies of higher birth weight than were women in other groups. However, the differences in birth weight between the energy expenditure categories were small, and mean birth weights within each group were within the normal range. Women in the medium energy expenditure group also had fewer incidences of prelabor rupture of membranes and women in the lower energy expenditure category had increased risks of antepartum admission to the hospital and preterm birth. A variety of other differences were observed in pregnancy outcomes for women in each of the categories of energy expenditure, but most of these differences were explained by the characteristics of the women in each expenditure level rather than the exercise pattern itself.

CONCLUSION

These results indicate that the effects of daily energy expenditure on pregnancy outcome are not great. Enthusiasm for counseling pregnant women of the benefits or hazards of extremes in daily activity should be tempered by the relative lack of an effect and the fact that most apparent differences are due to confounding variables rather than the exercise itself.

Low dose aspirin for the treatment of fetal growth restriction: a randomized controlled trial

The purpose of this study was to investigate the hypothesis that maternal administration of 100mg aspirin each day will improve birth-weight and other measures of neonatal size when given as a treatment to pregnancies complicated by fetal growth restriction and umbilical-placental insufficiency. A randomized, double-blind, placebo controlled study design was employed; 51 pregnant women were enrolled. The entry criteria were a fetal abdominal circumference < 10th per centile together with an umbilical artery Doppler systolic/diastolic ratio > 95th per centile between 28 and 36 weeks' gestation. Compliance was assessed by serial measurement of maternal serum thromboxane B2 levels. The mean gestational age at enrolment was 32 weeks and at delivery was 36 weeks. There were no differences between the 2 groups in gestational age at birth; birth-weight or birth-weight ratio; circumferences of the head, chest or abdomen; skin fold thicknesses; or neonatal morbidity. Low dose aspirin therapy did not alter Doppler systolic/diastolic ratios. After 14 days therapy, mean thromboxane B2 levels fell more than 80% from baseline values; 10.5% of women did not demonstrate biochemical confirmation of aspirin ingestion, despite verbal confirmation of compliance. We conclude that low dose aspirin therapy is not of benefit in the treatment of pregnancies complicated by fetal growth restriction and umbilical-placental insufficiency between 28 and 36 weeks' gestation.

Time course of changes in lung mechanics following fetal steroid treatment

We studied the effect of a single-dose, corticosteroid treatment on preterm lambs (gestational age: 128 d). A low, medium, or high betamethasone dose (0.1, 0.5, and 2.0 mg/kg) or saline control was administered directly to the fetus by ultrasound-guided intramuscular injection 48 h before delivery. A second group received either the high dose of betamethasome or saline 24 h before delivery. The lambs were delivered at 128 d gestation, anesthetized with ketamine, and ventilated for 50 min. Respiratory system elastance and resistance were measured at 10-min intervals using multiple linear regression analysis of pressure, flow, and volume. Similarly, estimates of lung mechanics were calculated from transpulmonary pressure. The viscoelastic time constant (tau) was calculated by fitting an exponential to the pressure changes occurring after occluding the airway during expiration. Excised lung volume at 40 cm H2O and lung weight were used to calculate specific elastance and resistance correcting for lung size using volume or weight, respectively. Of the 13 lambs in the 48-h high-dose betamethasone group, five developed pulmonary interstitial emphysema (PIE) as did 3 of 11 animals in the high-dose group treated 24 h before delivery. These animals were analyzed separately. The lambs receiving medium- or high-dose (24 and 48 h predelivery) betamethasone had significantly lower elastance and a trend toward lower resistance when compared with the control groups. Ten minutes after delivery, the animals that developed PIE all had elastance values comparable to that of the control animals despite corticosteroid treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Catecholamine response to ultrasonographically guided percutaneous blood sampling in fetal sheep

OBJECTIVE

The purpose of this study was to investigate the fetal catecholamine and arterial blood gas responses to ultrasonographically guided percutaneous needle aspiration of blood from a fetal cardiac ventricle.

STUDY DESIGN

A crossover trial design was used. Nine pregnant sheep of 120 to 130 days' gestation were stratified to either percutaneous fetal blood sampling or a sham experiment performed on the first day, and the alternative study on the following day. Arterial blood samples were withdrawn from chronically implanted catheters.

RESULTS

Percutaneous fetal blood sampling caused small but statistically significant increases in mean plasma epinephrine and norepinephrine levels 5 seconds after the procedure. Levels thereafter were similar to baseline values. Arterial pH and PCO2 values were unaltered except in one fetus, where blood sampling was followed by bradycardia with acidosis and elevated catecholamine levels.

CONCLUSIONS

Ultrasonographically guided percutaneous fetal blood sampling from a cardiac ventricle in sheep produces a rise in catecholamine levels that return to baseline values within 5 minutes. This technique provides an alternative to chronic catheterization for some experiments in which blood sampling or drug injection is required. The results also indicate that needle insertion produces only a modest and transient stress response in the fetus.

Effects of frequent ultrasound during pregnancy: a randomised controlled trial

Despite widespread application of ultrasound imaging and Doppler blood flow studies, the effects of their frequent and repeated use in pregnancy have not been evaluated in controlled trials. From 2834 women with single pregnancies at 16-20 weeks gestation, 1415 were selected at random to receive ultrasound imaging and continuous-wave Doppler flow studies at 18, 24, 28, 34, and 38 weeks gestation (the intensive group) and 1419 to receive single ultrasound imaging at 18 weeks (the regular group). Outcome data was obtained from 99% of women who entered the study. The only difference between the two groups was significantly higher intrauterine growth restriction in the intensive group, when expressed both as birthweight < 10th centile (relative risk 1.35; 95% confidence interval 1.09 to 1.67; p = 0.006) and birthweight < 3rd centile (relative risk 1.65; 95% confidence intervals 1.09 to 2.49; p = 0.020). While it is possible that this finding was a chance effect, it is also plausible that frequent exposure to ultrasound may have influenced fetal growth. Repeated prenatal ultrasound imaging and Doppler flow examinations should be restricted to those women to whom the information is likely to be of clinical benefit.

A comparison of abdominal and vaginal examinations for the diagnosis of engagement of the fetal head

The diagnosis of engagement of the fetal head is mandatory before operative vaginal delivery is to be attempted. There is widespread belief that the fetal head is engaged in the maternal pelvis when vaginal examination reveals that the bony presenting part has reached the level of the ischial spines. However, it is also claimed that in the presence of moulding the vaginal findings may be misleading and that it may be preferable to make the diagnosis by abdominal examination of the level of the fetal head in relation to the pelvic brim. In order to evaluate the relative merits of each of these 2 systems of physical examination, a retrospective study was made of 104 cases which had been evaluated for possible operative vaginal delivery by both methods. Prediction of successful vaginal delivery was greater by abdominal criteria (94%) than by vaginal criteria (80%) (p < 0.01). When evaluated by maximum likelihood logistic regression analyses, the factor of greatest importance in determining the probability of allocation of a case to each of the engagement groups was moulding (odds ratio 2.17; 95% confidence intervals 0.75-6.27). We conclude that when these 2 methods of assessment produce different diagnoses, the major factor responsible is moulding of the fetal head. Clinical evaluation prior to operative vaginal delivery must include abdominal examination and reliance on vaginal findings alone may prove misleading when moulding is present.

Intrauterine intravascular transfusion for fetal haemolytic anaemia: the Western Australian experience

OBJECTIVE

To report the first four years' clinical experience with fetal intravascular blood transfusion for the treatment of fetal haemolytic anaemia in Western Australia.

SETTING

King Edward Memorial Hospital, Perth, which is the sole tertiary level perinatal centre in Western Australia with a referral base of approximately 25,000 pregnancies each year.

METHODS

Transfusion was by injection of packed cells from Rh-negative donors into the fetal umbilical vein near the site of insertion into the placenta. Fetal haemoglobin levels were measured before and after each transfusion. In most cases, the fetus was paralysed by intramuscular tubocurarine.

RESULTS

Sixty intravenous transfusions were performed in 20 pregnancies. At the time of the initial transfusion, the mean haemoglobin level was 5.8 g/dL (range, 2.5-8.5 g/dL) and six fetuses had signs of hydrops. The case survival rate was 80% and the procedure survival rate was 93%. Three of the deaths occurred in the first five cases. Caesarean section was performed during two of the procedures, one because of bleeding from the cord puncture site and one because of tamponade of the umbilical vessels.

CONCLUSION

Fetal intravascular transfusion is a highly effective treatment for fetal alloimmunisation and allows pregnancies to continue to term and to be delivered vaginally. However, the procedure may be difficult and requires a team approach with ready access to fetal monitoring and emergency caesarean section. Our results suggest that increasing experience of the team is a major factor in improved outcome.

Indomethacin for the treatment of polyhydramnios: a case of constriction of the ductus arteriosus

Prenatal administration of indomethacin for the treatment of polyhydramnios at 27 weeks' gestation resulted in the rapid restoration of normal amniotic fluid volume. However, after 16 days therapy, fetal echocardiography revealed constriction of the fetal ductus arteriosus which did not reverse during the 17 days after the therapy was discontinued. The constriction resulted in right heart failure but no long-term effects on the infant after birth. Indomethacin is a powerful treatment for polyhydramnios but its use requires close monitoring of the fetal heart.

Lambing performances and wool production of maiden and adult Merino ewes fed different amounts of lupin seed in mid-pregnancy

Maiden (1.5 years old, 42 kg) and adult (4-5 years old, 55-58 kg) Merino ewes were divided into 15 groups of 30 on the basis of ovulation rate (three classes of ewe: maiden = 1, adult = 1 or 2) and fed lupin seed (91% digestible, 33% crude protein) three times per week at rates equivalent to 0, 100, 200, 300, or 400 g head-1 day-1 from day 28 to day 108 of pregnancy (17 December to 6 March). Thereafter the ewes were fed at the same rate (400-500 g head-1 day-1 of lupins, ad libitum oaten hay) until two weeks post lambing. They were grazed on two hectare plots from day 22 of pregnancy until two weeks after lambing; the plots had 1.3 tomes dry matter/ha (54% digestible, 11% crude protein) at the start of grazing. The differential feeding induced changes in liveweight and condition score during mid-pregnancy ranging across the ewe classifications from 8.4 to +5.0 kg and -1.6 to +1.3 units, respectively. In late pregnancy and lactation there were compensatory changes in the ewes, so that at 12 weeks post-lambing the difference between the animals from the mid-pregnancy feeding treatments had been reduced to less than 2 kg. There was a significant relationship (linear P < 0.001) between lamb birth weight and rate of lupin feeding during mid-pregnancy. For every 0.1 kg head-' day-' of lupins fed, lamb birth weight increased by 0.11 kg. There was no significant effect of class of ewe on this relationship. Maternal plasma glucose levels at about day 100 of pregnancy increased with rate of lupin feeding (interaction between class of ewe and feeding treatment P < 0.01). Ultrasound measurements of cotyledon diameters were greater (P < 0.001), and resistance to maternal placental blood flow less (assessed by Doppler arterial waveform analysis, interaction between class of ewe and feeding treatment P < 0.05) at about day 100 of pregnancy in ewes fed 400 g head-1 day-1 of lupins compared with unfed ewes. These findings indicated that in the unfed ewes there was a reduced nutrient supply to the fetus from reduced glucose availability, smaller placentas and less expansion of the placental vasculature. Growth of the lambs to four weeks of age increased with rate of lupin feeding in mid-pregnancy (quadratic P < 0.05), although the actual differences in weight at four weeks of age were small (<1 kg). Annual wool production from the ewes was significantly affected by the differential feeding during mid-pregnancy, with clean fleece weight (linear P < 0.01), staple length (linear P < 0.01) and strength (linear P < 0.001) increasing with increased rate of lupin feeding, and the position of break shifted from the period of pregnancy to after lambing (quadratic P < 0.01). Mean fibre diameter was not significantly affected by any treatment. It was concluded that the ewes at greatest risk from underfeeding in mid-pregnancy, in terms of lamb and wool production, were maiden ewes and adult ewes bearing twins.

The influence of maternal undernutrition in ovine twin pregnancy on fetal growth and Doppler flow-velocity waveforms

The effects on placental blood flow velocity of maternal undernutrition during mid pregnancy were investigated in 38 twin bearing pregnant sheep by Doppler analysis of umbilical and uteroplacental arterial waveforms. Mid pregnancy undernutrition resulted in fetal growth restriction manifest at term gestation by reduced mean birth weight. Arterial waveform systolic/diastolic ratios from the umbilical and uteroplacental arterial circulations were not influenced by maternal nutrition either during the dietary deprivation or during a subsequent period of dietary supplementation. An effect of heart rate on systolic/diastolic ratios could not be demonstrated. The results indicate that the fetus responds to mid pregnancy maternal undernutrition with restricted growth but without alterations in systolic/diastolic ratios in umbilical or uteroplacental arterial waveforms.

Doppler flow velocity waveform analysis in high risk pregnancies: a randomized controlled trial

OBJECTIVE

To test whether the introduction of Doppler waveform analysis into the ultrasound department of a tertiary level hospital reduces neonatal morbidity and improves obstetric management.

DESIGN

A randomized controlled trial.

SETTING

Department of Ultrasound, King Edward Memorial Hospital, Perth, Western Australia.

SUBJECTS

505 women with pregnancy abnormalities referred to an ultrasound department for fetal investigation during the third trimester.

INTERVENTION

Continuous wave Doppler studies of umbilical and uteroplacental arterial circulations. Results were revealed to patients and clinicians.

MAIN OUTCOME MEASURES

Principal end point was the duration of neonatal stay in hospital; other end points included the number and type of fetal heart rate monitoring studies, obstetric interventions, frequency of fetal distress, birthweight, Apgar scores and need for neonatal intensive care.

RESULTS

There was no effect on the duration of neonatal stay in hospital. Small trends in obstetric management were observed with study group patients having fewer contraction stress tests, less likelihood of antepartum fetal distress, and more likelihood of fetal distress after induction of labour leading to emergency caesarean section. Depressed Apgar scores were more frequent in the study group.

CONCLUSION

Introduction of Doppler waveform studies did not result in reduced neonatal morbidity but did have a small effect on obstetric management. For each institution the role of Doppler studies in late pregnancy will be influenced by the usage of other tests of fetal welfare already entrenched in clinical practice.