Neonatal cerebral Doppler flow velocity waveforms in the uncomplicated pre-term infant: reference values

In a longitudinal study of 217 infants delivering at < 37 completed weeks gestation, Doppler flow velocity waveforms were obtained and resistance index (RI) values calculated from the middle (MCA) and anterior (ACA) cerebral arteries during the first 10 days of life. One hundred thirty-seven of these infants were non-acidotic at delivery and during the early neonatal period, and had normal cerebral ultrasound scans throughout the study period. These infants formed the reference group. In three gestational subgroups considered (< or = 32 weeks, 33-34 weeks, > or = 35 weeks) from the reference group, the median RI for both the ACA and MCA was noted to fall significantly during the first 12 h of life (P < 0.01 for all groups). For infants delivering at > or = 33 weeks gestation, both MCA and ACA RI values reached a steady state with no significant change in the median value for the remainder of the study period. For infants delivering at < or = 32 weeks, there was a further significant fall in both the MCA and ACA RI between 12 and 24 h of life (P < 0.05), after which a steady state value was reached. During the first 12 h of life the RI for both vessels was significantly higher in infants delivering at < or = 32 weeks compared to the more mature infants (P < 0.01), but for the remainder of the study period, there were no significant differences in RI values between the gestational subgroups.(ABSTRACT TRUNCATED AT 250 WORDS)

Risk of preterm delivery in pregnant women with group B streptococcal urinary infections or urinary antibodies to group B streptococcal and E. coli antigens

OBJECTIVE

To establish whether there is an association between preterm delivery and either group B streptococcal urinary infection or the presence of urinary antibodies to group B streptococcal or E. coli antigens.

DESIGN

A prospective study with urine culture and antibody measurement performed at the first antenatal visit and at 28 weeks gestation.

SETTING

Ninewells Hospital, Dundee.

SUBJECTS

Two thousand and forty-three women registering consecutively at an antenatal clinic.

MAIN OUTCOME MEASURE

Delivery at less than 37 weeks gestation.

RESULTS

No increase in preterm delivery was observed in women with positive urine cultures for group B streptococci either at booking or at 28 weeks, even when confirmed by positive repeat cultures. Preterm delivery was more common in women with elevated urinary antibodies to E. coli antigens at booking (relative risk 1.81, 95% CI 1.22-2.68, P = 0.005) and at 28 weeks (relative risk 2.36, 95% CI 1.60-3.48, P < 0.0001) and to group B streptococcal antigens at 28 weeks (relative risk 2.24, 95% CI 1.46-3.43, P = 0.0003).

CONCLUSIONS

These data do not support previous reports that positive urine cultures for group B streptococci are associated with an increased risk of preterm delivery. Our report of an association between elevated levels of urinary antibodies and preterm delivery is a new finding consistent with the possibility that a local inflammatory response to uro-genital infection may be important in stimulating the onset of preterm labour. The results suggest that screening for urinary antibodies at 28 weeks gestation might help to identify a group of women at increased risk of prematurity.

Nitric oxide: a new biological messenger molecule

Nitric oxide, a recently discovered gaseous biological messenger molecule, has been found to play a fundamental regulatory role in the body. It is involved in the cardiovascular, immune, reproductive, and digestive physiology and its presence in the brain indicates that it will have a neuronal function as well. Several areas of research suggest that low levels or absence of nitric oxide may be the underlying cause of some forms of essential hypertension and impotence, while over-production could be the cause of neuronal damage, septic shock, and immune-related tissue damage.

Prevalence of HIV among childbearing women and women having termination of pregnancy: multidisciplinary steering group study

OBJECTIVE

To determine the prevalence of HIV among pregnant women, in particular those whose behaviour or that of their partners put them at "low risk" of infection.

DESIGN

Voluntary named or anonymous HIV testing of pregnant women during 21 months (November 1988 to July 1990).

SUBJECTS AND SETTING

All women who planned to continue their pregnancy and attended clinics serving the antenatal populations of Edinburgh and Dundee. All women admitted for termination of pregnancy to gynaecology wards serving the pregnant populations of Dundee and outlying rural areas.

MAIN OUTCOME MEASURES

Period prevalence of HIV antibody positivity.

RESULTS

91% of antenatal clinic attenders and 97% of women having termination of pregnancy agreed to HIV testing on a named or anonymous basis. HIV period prevalences for antenatal clinic attenders and women having termination of pregnancy tested in Dundee were 0.13% and 0.85% respectively, and for antenatal clinic attenders tested in Edinburgh 0.26%. For those at "low risk" rates for antenatal clinic attenders and women having termination of pregnancy in Dundee were 0.11% and 0.13%, and for antenatal clinic attenders in Edinburgh 0.02%. In Dundee HIV prevalence among women having a termination of pregnancy (0.85%) was significantly greater than that among antenatal clinic attenders (0.13%).

CONCLUSIONS

HIV infection is undoubtedly occurring among women at "low risk," and it is clear that a policy of selective testing of those at only "high risk" is inadequate for pregnant women living in areas of high prevalence such as Edinburgh and Dundee. Moreover, when studying pregnant populations in such areas there is the need to include those having a termination of pregnancy.

Cerebral pathology in the very low birthweight infant: predictive value of peripartum metabolic acidosis

One-hundred-and-three infants with a birthweight of less than 1500 g and delivering at a gestation of less than 32 weeks were examined by serial cranial ultrasound scans. A capillary blood sample was drawn for blood gas analysis within 1 h of birth in all cases. The subsequent development of intracranial pathology was found to be significantly associated with gestation at delivery (P less than 0.01), birthweight (P less than 0.01) and base deficit within 1 h of birth (P less than 0.001). For infants with a base deficit of greater than 5.0 mmol/l within the first hour of life, the sensitivity for predicting the subsequent development of cerebral pathology was 51.5% with a specificity of 97.3%, and a positive predictive value of 97.1%. This relationship between a metabolic acidosis within 1 h of birth and the subsequent development of cerebral pathology held for both major and minor degrees of pathology, but was stronger in those infants developing major cerebral pathology. The study suggests that improved surveillance of the very preterm infant during labour and at birth with the aim of reducing the incidence of metabolic acidosis at birth, may help to reduce subsequent intracranial pathology, and thereby perinatal and long-term morbidity.

Prevalence of HIV antibody and pregnancy in Tayside, 1984-9: background to screening

OBJECTIVE

To determine age specific prevalence of HIV antibody, incidence of pregnancy, and likelihood of detection and correct assignment to risk category by antenatal screening of women known to be positive for HIV antibody, from 1984 to 1989.

DESIGN

Retrospective analysis of reproductive history and risk behaviour of women positive for HIV antibody and prediction of detection by screening on the basis of blood group samples, Guthrie tests, and rubella tests.

SETTING

City of Dundee, where the prevalence of HIV is high, since the appearance of HIV in 1984, predominantly among heterosexual intravenous drug users.

PATIENTS

All (61) women known to be positive for HIV antibody who had had clinically indicated tests, for whom case notes were available for 60.

MAIN OUTCOME MEASURES

Risk assessment according to case notes and reported to the laboratory, incidence of infection, geographical location, age, date of positive test result, and reproductive history.

RESULTS

With 61 infected women the overall minimum prevalence among women within the city of Dundee was 0.67/1000 and 2.9/1000 among women in their third decade. Of the 60 women whose reproductive history was available, 35 had 57 pregnancies, 36 of which occurred after seroconversion was known to have taken place, representing 8.7% of the total number of affected pregnancies reported for the United Kingdom. If antenatal screening for HIV had been performed between 1984 and 1989 it could not have detected positivity for HIV antibody in 25 (42%) women who had no pregnancies during this time. Among the remaining 35 women, screening samples taken for blood grouping could have identified a maximum of 34 (57%), samples taken to check rubella susceptibility a maximum of 22 (37%), and blood spots on Guthrie cards a maximum of 19 (32%). Retesting would have occurred in 14 women 33 times with samples taken for blood grouping, but three and four women would have been tested twice using samples taken for rubella testing and Guthrie cards respectively. Anonymous screening would have been unable to determine risk category as a history of intravenous drug use was known in 47 (79%) women before testing but this was increased by a further 5 (8%) who admitted to it after the test result was known.

CONCLUSION

Interpreting the results of antenatal screening programmes will be complex and will underestimate overall prevalence of HIV antibody among women; this will be exaggerated by strategies based on anonymous testing with Guthrie cards or on samples taken for rubella testing, which do not include women who have had an earlier loss of pregnancy. Only open testing with consent will permit satisfactory attribution to

Epidural analgesia and its effect on umbilical artery flow velocity waveform patterns in uncomplicated labour and labour complicated by pregnancy-induced hypertension

Umbilical artery flow velocity waveforms were obtained using continuous-wave Doppler ultrasound to examine the effect of epidural analgesia on peak systolic/least diastolic ratio (A/B ratio) in 38 women in uncomplicated labour, and 12 women with pregnancy-induced hypertension (PIH). In the uncomplicated group there was no significant change in A/B ratio after epidural analgesia, but in the PIH group there was significant correlation between the fall in mean blood pressure and the fall in A/B ratio at 30 min after induction of epidural analgesia (r = 0.85, p less than 0.001). This suggests that epidural analgesia in PIH is associated with a reduction in placental resistance and may be beneficial to the fetus.

Umbilical artery waveform analysis and biophysical profile. A comparison of two methods to identify compromised fetuses

Sixty-nine singleton high-risk pregnancies were assessed with both umbilical artery flow velocity waveform analysis and fetal biophysical profile within 10 days of delivery. An abnormal outcome, as defined as either small for gestational age at birth (SGA) or fetal distress during labour, was found in 30 babies. The peak systolic/end diastolic (A/B) ratio from the umbilical artery had a higher sensitivity (37%), specificity (92%), positive predictive value (79%) and negative predictive value (66%) than the fetal biophysical profile (27%, 82%, 53%, and 59%, respectively) in the diagnosis of abnormal outcome. Additional information from a real-time ultrasound assessment, such as the diagnosis of malformations and oligohydramnios could justify a combination of the two methods in antenatal monitoring of high-risk pregnancies.

Fetal umbilical artery flow velocity waveforms: prediction of small for gestational age infants and late decelerations in labour

The relationship between fetal umbilical artery waveform patterns and (a) small for gestational age infants or (b) late fetal heart rate (FHR) decelerations in labour was examined in 205 clinically high-risk pregnancies. All pregnancies were studied using continuous-wave Doppler Ultrasound within 7 days of delivery. Waveforms were analysed by calculating a ratio of peak systolic frequency to end diastolic frequency (A/B ratio). An abnormal Doppler result was defined as being above the 97th centile for gestation from our previously derived normal values. Abnormal Doppler results occurred in only 38% of small for gestational age (SGA) infants and in 70% of those developing late decelerations in labour. Doppler ultrasound is a poor predictor of SGA infants, but may identify a high proportion of cases at risk of developing late FHR decelerations in labour.

Effect of a new nonionic contrast agent, ioxilan, on human erythrocytes and the hemostatic and serum complement pathways

A new nonionic contrast medium (CM), ioxilan, was compared with iohexol and iopamidol. Following incubation of whole heparinized blood with CM, the morphology and osmotic fragility of erythrocytes were studied, the former by transmission electron microscopy. Effects on platelets and hemocoagulation were determined by standard hematologic procedures. Effects on serum complement were evaluated by measurement of total hemolytic complement (CH50), C3, C4 consumption and the presence in serums of C3c as determined by immunoelectrophoresis. Ioxilan affected the erythrocyte membrane less than iohexol and iopamidol: the latter two produced acanthocytes, whereas ioxilan had no effect on erythrocyte morphology; also, erythrocytes exposed to ioxilan (and iopamidol) were more resilient to hypotonic saline solutions than those exposed to iohexol. In all tests, all CM showed anticoagulant activity, albeit much less when compared with ionic CM. At equal iodine concentration, ioxilan reduced the platelet aggregation and whole blood clotting time more than did iohexol. None of the CM activated the serum complement system.

Mothering problems and child morbidity amongst "mothers with emotional disturbances"

In a study of 1,955 primigravidae who gave birth to a live singleton baby, 227 (11.6%) scored 'positive' (7+) in an antenatal Health Questionnaire enquiring into pre-pregnancy emotional disturbances. This group of mothers had more frequent depression, and this was of longer duration after their delivery compared with those scoring less than 7 (less than or equal to 6). Those scoring 7+ were less likely to breast-feed and the infants were more often ill during the first year of life. There were also differences in 'minor obstetric complications' between the two survey groups. This suggests that the application of this Health Questionnaire antenatally can identify emotionally vulnerable women, who could benefit from support and education during the antenatal period.

The predictive value of fetal breathing movements in the diagnosis of preterm labour

A real time ultrasound investigation was performed on 64 patients who presented in threatened preterm labour. Fetal breathing movements (FBM) were absent in 17 patients, all of whom were delivered within 56 h. FBM were present in 47 patients of whom five were delivered within 56 h from examination and four of these had spontaneous rupture of membranes and/or chorioamnionitis. In 33 the pregnancy continued for at least 1 week. Two of the fetuses with false negative results showed a distinct breathing pattern different from the rest of the study group. This suggests that pattern recognition of fetal breathing might improve the specificity of this investigation.

The effect of fetal heart rate on umbilical artery flow velocity waveforms

Umbilical artery flow velocity waveforms were obtained using continuous wave Doppler ultrasound in 85 normal pregnancies (25 antepartum, 60 intrapartum) to examine the relation between fetal heart rate, end systolic/end diastolic ratio (A/B ratio) and resistance index (RI). Our results demonstrated a significant negative correlation between fetal heart rate, A/B ratio and RI (in the antepartum group r = -0.49, and in the labouring group r = -0.65). It is therefore important when performing mathematical analysis of umbilical artery flow velocity profiles to make a statistical allowance for fetal heart rate.

Mortality and morbidity in infants born between 20 and 28 weeks gestation

Of 149 infants with ultrasound evidence of gestational age, born in Ninewells Hospital at between 20 and 28 weeks gestation over a 5-year period, 50 were alive at birth. Of these infants, 21 died within 1 week, a further three died within 1 month and a further two within 18 months. Of the 24 survivors, 8 (33%) have significant handicap. The obstetric factors leading to delivery and the mode of delivery are discussed.

Non-stress antenatal cardiotocography--a prospective blind study

A prospective blind study of non-stress antenatal cardiotocography was undertaken in a group of 216 'high risk' pregnancies. The 'Cardiff' scores and the outcome of the pregnancies were compared subsequently. Low scores were associated with infants that were small-for-gestational age and fetal distress in labour, while high scores were associated with normal intrauterine growth. Although antepartum cardiotocography is predictive of fetal and neonatal outcome the extent to which its availability will prevent adverse outcome appears limited.

Non-stress antenatal cardiotocography--a prospective randomized clinical trial

A randomized controlled trial examined the effects of non-stress antepartum cardiotocography on obstetric management and assessed its usefulness as a diagnostic test of fetal compromise. Daily cardiotocograph recordings were made in 396 antenatal patients at increased risk of fetal compromise but were withheld from the clinicians responsible for care in half the cases. The frequency of intrapartum fetal distress and low Apgar score was similar in the two groups. The three normally-formed perinatal deaths all occurred in the revealed group but in only one case could earlier obstetric intervention have altered the outcome. Availability of non-stress cardiotocography was not associated with an increased rate of induction of labour or caesarean section.

An assessment of perinatal mortality in twin pregnancies in Dundee

An analysis of all perinatal deaths occurring in twin pregnancies in Dundee women from 1956 to 1983 was performed. The uncorrected perinatal mortality rate fell from 116/1000 births in 1956-60 to 16/1000 births in 1981-83, this fall almost entirely taking place after 1975. Causes of death were identified using the Aberdeen Classification and a reduction in deaths in all cause groupings occurred. About half of the deaths were in the Premature, Cause Unknown group and a marked decrease in deaths in this group made the largest contribution to the improved perinatal mortality rate. This fall was partly due to a reduction in the incidence of extreme prematurity and low birth weight. Changes in obstetric management which may have influenced outcome included the introduction of routine early pregnancy ultrasound scanning, the use of tocolytic drugs, intrapartum fetal monitoring, epidural analgesia and an increase in Caesarean section rate from 2% in 1956-60 to 39% in 1981-83.

Intrauterine volume, fetal abdominal area and biparietal diameter measurements with ultrasound in the prediction of small-for-dates babies in a high-risk obstetric population

The value of fetal biparietal diameter and abdominal area, total intrauterine, intra-amniotic and placental volume measurements for predicting small-for-dates babies in a high-risk obstetric population was investigated in 130 women. A parallel planimetric area method was used to measure volume. The commonest risk factors were suspected intrauterine growth-retardation, hypertensive complications and previous poor obstetric history. The prevalence of birthweight at and below the 10th or 3rd centiles was 30 and 16% respectively. Fetal abdominal area and total intrauterine volume measurements had the highest and comparable sensitivity, specificity and positive predictive value in the detection of infants with birthweights of less than or equal to 10th and less than or equal to 3rd centiles. While these measurements are of use in consolidating the clinical diagnosis of small-for-dates fetuses (growth retardation), high false positive rates (10% and 16-17% for birthweights less than or equal to 10th centile, and less than or equal to 3rd centile respectively) make further discriminatory tests necessary for part of the population.