Numerical analysis of the human fetal heart rate: the quality of ultrasound records

A method is described for the computerized numerical analysis of fetal heart periods (pulse intervals). It uses a digital filter to separate the record into its high- and low-frequency components and, after removal of baseline variation, identifies accelerations and decelerations of all sizes. It provides an objective method for separating episodes of high heart period variation, normally associated with fetal movements, from episodes of low variation. When Doppler ultrasound is used in the last 10 weeks of gestation, failure time averages 40%. Signal loss is not randomly distributed; it is on average 75% greater during episodes of high heart period variation, although it is not particularly associated with fetal movements as identified by nurse or patient. Nevertheless a comparison of simultaneous direct ECG and ultrasound records shows that the latter provide reasonable statistical measures of heart period variation, and also of accelerations and decelerations provided that signal loss is taken into account. The system thus provides a particularly useful adjunct to the analysis of antenatal human fetal heart rate records.

Numerical analysis of the normal human antenatal fetal heart rate

A numerical method for separation of the frequency components of the fetal heart rate, and for identifying episodes of high or low variation, was applied to 196 64-minute ultrasound records in normal pregnancies during the last half of gestation. Most variables of heart period variation increased with gestation, as did the incidence of accelerations. Before 35 weeks, accelerations of greater than or equal to 14 beats/minute did not occur in all records. Cyclic episodes of low and high variation ("unreactive' and "reactive' episodes), associated with rest-activity cycles, could be identified from 27 weeks onwards. After 36 weeks gestation the length of low variation episodes increased and the variation during these episodes fell. Near term, low variation episodes lasted up to 40 minutes. It is concluded that on scrutiny of fetal heart rate records for evidence of normality, or otherwise, due account should be taken of gestational age.

Monoclonal antibodies to human syncytiotrophoblast

Two monoclonal antibodies, NDOG1 and NDOG2, have been produced which are directed towards human syncytiotrophoblast. The antigens detected by these antibodies are absent from human liver, heart, kidney, brain and from normal human sera. The NDOG1 antigen but not NDOG2 antigen is a component of pregnancy sera and falls to undetectable levels within 6 hours of placental delivery. This molecule is not human chorionic gonadotrophin, human placental lactogen, placental alkaline phosphatase. SP1 or PAPP-A. Immunoperoxidase staining shows that both antigens are on apical aspects of the syncytiotrophoblast and not in the villous stroma.

Prediction of small-for-dates infants by measurement of symphysial-fundal-height

A standard chart of symphysial-fundal height from 20 to 40 weeks of pregnancy was derived from measurements in 103 women who were delivered of infants weighing between the 25th and 90th centile for gestation. The chart was used to predict birth weight in a group of 138 high-risk patients. Thirty (73.1 per cent) of 41 infants with birth weight for gestation less than 10th centile could be detected by this one clinical measurement. A single measurement was most accurate for detecting low birth weight for gestation at 32 to 33 weeks. It is suggested that symphysial-fundal height measurements should be made routinely on all antenatal patients and that each obstetric unit should derive its own standard curves.

Nonstressed antepartum heart rate monitoring: implications of decelerations after spontaneous contractions

Fetal outcome in 98 patients with spontaneous antepartum late decelerations was studied by combining the data of two obstetric departments. Heart rate variability was used to classify the different patterns into two categories: terminal and decelerative. In 14 of the 47 pregnancies in which a terminal pattern was found, intrauterine death occurred within a week. Of the remaining 33 fetuses, 71% were acidemic at elective cesarean section (CS). In contrast, all of the 51 fetuses with a decelerative cardiotocogram (CTG) survived the antenatal period, and only two of 25 were acidemic at elective CS. Labor was induced in 20 patients with a decelerative CTG, and fetal distress occurred in 12, of whom 10 were eventually delivered by CS. All fetuses with a repetitive decelerative heart rate pattern antepartum developed distress in labor. In contrast, an isolated deceleration, on one occasion only, was not associated with distress during labor, except in growth-retarded fetuses. The clinical implications of these findings are discussed and the results are compared with those of oxytocin contraction stress tests.

Hypertension during pregnancy with and without specific treatment; the development of the children at the age of four years

In a controlled trial pregnant women who were hypertensive before the 28th week of gestation were randomly allocated to treatment with methyldopa or no anti-hypertensive treatment. The children from these pregnancies have been re-examined at four years of age and their development compared with a random sample from the same maternity hospital population. Their health, height, weight, and the incidence of sight, hearing and speech problems did not differ. None had gross neurological abnormalities. Boys in the treated hypertensive group had significantly smaller heads than in the other two groups, but there was no correlation between head circumference and developmental score in this group (r = 0.020). On average the children in the random sample were the most advanced when assessed by a global score of development. In each developmental sector the mean score for the treated hypertensive group was consistently higher than the untreated hypertensive group. We conclude that maternal hypertension is associated with slight developmental delay in early childhood. There are some indications that treatment with methyldopa may reduce this effect.

The concentrations of the prostaglandins E and F, 13 14-dihydro-15-oxo-prostaglandin F and thromboxane B2. In tissues obtained from women with and without pre-eclampsia

The concentrations of prostaglandins E (PGE) and F (PGF), 13, 14-dihydro-15-oxo-prostaglandin F (PGFM) and thromboxane B2 (TXB2) were measured by specific radioimmunoassays in tissues obtained from women with and without pre-eclampsia. The concentrations of PGE in the amnion, chorion, decidua and placenta obtained from subjects with pre-eclampsia were significantly lower than those from subjects without pre-eclampsia. The concentration of PGE in these tissues increased significantly with gestational age and correlated with urinary oestrogen excretion. PGF concentrations were lower in the amnion and placenta of the pre-eclamptics compared to those without pre-eclampsia. The concentrations of PGFM in the amnion, decidua, and myometrium were lower in the pre-eclamptics. No significant difference in the TXB2 concentrations between the two groups of subjects were found. It is suggested that the altered tissue concentrations of prostaglandins in pre-eclamptics are due to the effects of gestational age and oestrogens and may or may not be involved in the pathogenesis of pre-eclampsia.

Coagulation problems in human pregnancy

Coagulation problems in pregnancy are primarily associated with overactivity of the intrinsic clotting system. This accounts for the increased incidence of thrombo-embolism during pregnancy. Where specific obstetric complications cause clotting problems the common underlying feature is usually placental pathology as in abruptio placentae, pre-eclampsia or hydatidiform mole. Abnormal activation of the clotting system is an early, and occasionally the first detectable feature of pre-eclampsia, but there is no evidence that this is a primary change. Therefore the role of anticoagulant treatment in the management of pre-eclampsia remains questionable. A new test for estimating factor VIII consumption is proving to be a sensitive index of early activation of the clotting system and can be used for the diagnosis of early pre-eclampsia.

Neonatal head circumference and the treatment of maternal hypertension

In a random controlled trial of methyldopa for the treatment of hypertension in pregnancy presenting before 28 weeks gestation, the newborn in the treated group had relatively smaller head circumferences. This difference persisted at two months of age when correction had been made for birth weight, gestation and sex, but was no longeer detectable at six or twelve months. Within the treated group no relationship was found between neonatal head circumference and the total amount or duration of methyldopa received during pregnancy. Comparison of treated and untreated groups according to the time of entry to the study showed that significant differences in neonatal head circumference were only present in patients who entered between 16 and 20 weeks gestation. It is possible that this could be a sensitive period for the interaction of fetal head growth and the onset of specific treatment in hypertensive pregnancy.

Thromboxane B2 and human parturition: concentrations in the plasma and production in vitro

The concentration of thromboxane B2 has been measured in the plasma of women during late pregnancy, during term and pre-term labour, in women with pre-eclampsia and in umbilical cord arterial and venous plasma. In addition, the rates of production of thromboxane B2 in vitro were determined for placental tissues obtained after spontaneous vaginal delivery or elective Caesarean section. The results obtained indicate significant differences during parturition between the sources and controlling mechanisms of thromboxane and prostaglandin production.

HLA antigens in severe pre-eclampsia

When the HLA types of 80 pre-eclamptic women and their husbands and 83 control couples were compared significantly more pre-eclamptic women had only one identifiable HLA B antigen, and were presumed to be homozygous at this locus. Those who were homozygous for HLA B were more likely to be homozygous for HLA A as well, and more likely to be homozygous for HLA A as well, and to have more severe pre-eclampsia. There was neither increased HLA incompatibility nor greater antigen-sharing between pre-eclamptic women and their husbands, but maternal HLA A and B homozygosity reduced the number of antigenic disparities between pre-eclamptic women and their husbands. The data are consistent with the hypothesis that maternal recessive immune-response genes may contribute to the development of pre-eclampsia. Alternatively maternal HLA homozygosity may predispose to fetal changes comparable to runting.

Closing volume during normal pregnancy

Serial lung function studies were performed in ten healthy, primiparous women aged 21--28. Measurements were made at two-monthly intervals during pregnancy and included functional residual capacity (FRC), total lung capacity (TLC), vital capacity (VC), specific conductance (SGaw) and closing volume (CV) on each occasion. Closing volume expressed as formular: (see text), showed a progressive rise during pregnancy in all subjects with a linear relationship to time (P less than 0.001, P greater than 0.01, respectively). No consistent changes in lung volume could be shown during pregnancy over the study period. It is suggested that the increase in closing volume during pregnancy might result in abnormalities of distribution of ventilation sufficient to explain the maternal blood gas disturbances of pregnancy.

Circulating immune complexes in pre-eclampsia

Sixteen patients with severe pre-eclampsia had more IgG-containing and C1q-binding circulating soluble immune complexes than did 16 matched women with normal pregnancies. The clinical features of preeclampsia may be explained by damage due to such complexes, although raised complex levels were also present in a few women with normal pregnancies. As immune complexes are so heterogenous in terms of the type of antigen, class and subclass of immunoglobulin, size, and complement-binding capacity, further investigations are needed to determine their role in normal and pre-eclamptic pregnancies.

Early platelet consumption in pre-eclampsia

One hundred and thirty-one women with chronic hypertension were studied serially during pregnancy to determine the sequence of events in the development of superimposed pre-eclampsia and to discover the time of onset. Twenty-seven women developed a sustained rise in plasma urate concentrations, which began at about 28 weeks' gestation and which is characteristic of pre-eclampsia. The mean platelet count was already significantly reduced and continued to fall until delivery, which was on average at 36 weeks' gestation. A comparable but smaller decrease in platelet count was seen in 55 women who had borderline but consistent increases in plasma urate concentrations. In 49 women whose plasma urate concentrations remained steady the platelet count did not change significantly before delivery. The reduced platelet count in women who develop pre-eclampsia suggests that increased platelet consumption is an early feature of the disorder.

Factor-VIII consumption in pre-eclampsia

In 50 women with high-risk pregnancies, increased factor-VII consumption, as estimated by the difference between the levels of factor-VIII-related antigen and factor-VIII clotting activity, correlated with the severity of pre-eclampsia, particularly when measured by increases in plasma-urate. Longitudinal studies of the evolution of pre-eclampsia demonstrated that increased factor-VIII consumption usually but not always developed before hyperuricaemia. The earliest time that abnormal factor-VIII consumption was demonstrated was at 18 weeks' gestation in a woman who had had two previous stillbirths. Subcutaneous heparin and oral dipyridamole failed to reverse the coagulation abnormality, and the fetus died in utero at 28 weeks' gestation. The renal and coagulation changes characteristic of pre-eclampsia were also seen in a patient without hypertension. This suggests that the concept of pre-eclampsia may need to be widened to include a non-hypertensive syndrome characterised by these changes in clotting and renal function.

Plasma urate and serum deoxycytidylate deaminase measurements for the early diagnosis of pre-eclampsia

The value of measuring plasma urate and serum deoxycytidylate deaminase (dCMP deaminase) for the early diagnosis of pre-eclampsia has been investigated in 45 patients. A combination of increased blood pressure and increased plasma urate identified 19 patients with a high incidence of fetal and maternal morbidity ascribable to pre-eclampsia. Seventeen of the 19 patients also had an increased serum dCMP deaminase. Serial antenatal observations for a mean period of 104 days (36-179 days) on 33 of the patients demonstrated that plasma urate and serum dCMP deaminase increased together as early changes in the development of pre-eclampsia. In six patients, blood pressure, plasma urate and serum dCMP deaminase all increased but in only one was the rise in blood pressure the first change. Elevations of plasma urate and serum dCMP deaminase are therefore both early features of pre-eclampsia. Serial measurements can give warning of the disorder before the appearance of other clinical features. The change in dCMP deaminase is probably another reflection of early renal involvement in the pre-eclamptic process.