Delivery or expectant management for prevention of adverse maternal and neonatal outcomes in hypertensive disorders of pregnancy: an individual participant data meta-analysis

OBJECTIVE

Hypertensive disorders affect 3-10% of pregnancies. Delayed delivery carries maternal risks, while early delivery increases fetal risk, so appropriate timing is important. The aim of this study was to compare immediate delivery with expectant management for prevention of adverse maternal and neonatal outcomes in women with hypertensive disease in pregnancy.

METHODS

CENTRAL, PubMed, MEDLINE and ClinicalTrials.gov were searched for randomized controlled trials comparing immediate delivery to expectant management in women presenting with gestational hypertension or pre-eclampsia without severe features from 34 weeks of gestation. The primary neonatal outcome was respiratory distress syndrome (RDS) and the primary maternal outcome was a composite of HELLP syndrome and eclampsia. The PRISMA-IPD guideline was followed and a two-stage meta-analysis approach was used. Relative risks (RR) and numbers needed to treat or harm (NNT/NNH) with 95% CI were calculated to evaluate the effect of the intervention.

RESULTS

Main outcomes were available for 1724 eligible women. Compared with expectant management, immediate delivery reduced the composite risk of HELLP syndrome and eclampsia in all women (0.8% vs 2.8%; RR, 0.33 (95% CI, 0.15-0.73); I2  = 0%; NNT, 51 (95% CI, 31.1-139.3)) as well as in the pre-eclampsia subgroup (1.1% vs 3.5%; RR, 0.39 (95% CI, 0.15-0.98); I2  = 0%). Immediate delivery increased RDS risk (3.4% vs 1.6%; RR, 1.94 (95% CI 1.05-3.6); I2  = 24%; NNH, 58 (95% CI, 31.1-363.1)), but depended upon gestational age. Immediate delivery in the 35th week of gestation increased RDS risk (5.1% vs 0.6%; RR, 5.5 (95% CI, 1.0-29.6); I2  = 0%), but immediate delivery in the 36th week did not (1.5% vs 0.4%; RR, 3.4 (95% CI, 0.4-30.3); I2 not applicable).

CONCLUSION

In women with hypertension in pregnancy, immediate delivery reduces the risk of maternal complications, whilst the effect on the neonate depends on gestational age. Specifically, women with a-priori higher risk of progression to HELLP, such as those already presenting with pre-eclampsia instead of gestational hypertension, were shown to benefit from earlier delivery. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

The role of autoimmunity in women with type 1 diabetes and adverse pregnancy outcome: A missing link

The incidence of pregnancy complications in women with type 1 Diabetes Mellitus (T1D) is greater than in healthy pregnant women. This has mostly been attributed to hyperglycemia. However, despite the implementation of stricter guidelines regarding glycemic control, pregnancy complications remain more common in women with T1D. This may suggest that other etiological factors are involved. We suggest that the immune response may play a role, since the immune response has to adapt during pregnancy in order to facilitate implantation, placental and fetal development, and aberrant immunological adaptations to pregnancy are involved in various pregnancy complications. Since T1D is an autoimmune disorder, the question rises whether the immune response of women with T1D is able to adapt properly during pregnancy. Here we review the current proof and views on the role of aberrant immunological adaptations in pregnancy complications and whether such aberrant adaptations could be involved in the pregnancy complications of T1D patients.

Relationship between general movements in neonates who were growth restricted in utero and prenatal Doppler flow patterns

OBJECTIVE

To investigate whether Doppler pulsatility indices (PIs) of the fetal circulation in cases of fetal growth restriction (FGR) are associated with the general movements (GMs) of the neonate after birth.

METHODS

This was a prospective observational cohort study including pregnancies with FGR diagnosed between June 2012 and September 2014. A diagnosis of FGR was based on an abdominal circumference or estimated fetal weight < 10^th percentile (in conjuction with abnormal Doppler) or declining fetal growth of at least 30 percentiles with respect to previous size measurements. Doppler parameters of the umbilical artery (UA), fetal middle cerebral artery (MCA) and ductus venosus (DV) were measured maximally 1 week prior to delivery. Cerebroplacental ratio (CPR) was calculated as MCA-PI divided by UA-PI. We assessed the quality of neonatal GMs 7 days after birth, around the due date if cases were born preterm, and at 3 months post-term. We performed a detailed analysis of the motor repertoire by calculating a motor optimality score (MOS).

RESULTS

Forty-eight FGR cases were included with a median gestational age at delivery of 35 (range, 26-40) weeks. UA-PI, MCA-PI and CPR correlated strongly (ρ, -0.374 to 0.472; P < 0.01) with the MOS on day 7 after birth, but DV-PI did not. Doppler PI measurements did not correlate with MOS at 3 months post-term.

CONCLUSION

Fetal arterial Doppler measurements are associated with the quality of neonatal GMs 1 week after birth, but this association is no longer evident at 3 months post-term. Brain sparing in particular is associated strongly with GMs of an abnormal quality. Copyright © 2016 ISUOG. Published by John Wiley & Sons Ltd.

Risk stratification for healthcare planning in women with gestational diabetes mellitus

BACKGROUND

To identify relevant factors predicting the need for insulin therapy in women with gestational diabetes mellitus (GDM) and secondly to determine a potential 'low- risk' diet-treated group who are likely to have good pregnancy outcomes.

METHODS

A retrospective analysis between 2011-2014. Multivariable backward stepwise logistic regression was used to identify the predictors of the need for insulin therapy. To identify a 'low-risk' diet-treated group, the group was stratified according to pregnancy complications. Diet-treated women with indications for induction in secondary care were excluded.

RESULTS

A total of 820 GDM women were included, 360 (44%) women required additional insulin therapy. The factors predicting the need for insulin therapy were: previous GDM, family history of diabetes, a previous infant weighing ≥ 4500 gram, Middle-East/North-African descent, multiparity, pre-gestational BMI ≥ 30 kg/m2, and an increased fasting glucose level ≥ 5.5 mmol/l (OR 6.03;CI 3.56-10.22) and two-hour glucose level ≥ 9.4 mmol/l after a 75-gram oral glucose tolerance test at GDM diagnosis. In total 125 (54%) women treated with diet only had pregnancy complications. Primiparity and higher weight gain during pregnancy were the best predictors for complications (predictive probability 0.586 and 0.603).

CONCLUSION

In this GDM population we found various relevant factors predicting the need for insulin therapy. A fasting glucose level ≥ 5.5 mmol/l at GDM diagnosis was by far the strongest predictor. Women with GDM who had good glycaemic control on diet only with a higher parity and less weight gain had a lower risk for pregnancy complications.

Caesarean section rates and adverse neonatal outcomes after induction of labour versus expectant management in women with an unripe cervix: a secondary analysis of the HYPITAT and DIGITAT trials

OBJECTIVE

To evaluate caesarean section and adverse neonatal outcome rates after induction of labour or expectant management in women with an unripe cervix at or near term.

DESIGN

Secondary analysis of data from two randomised clinical trials.

SETTING

Data were collected in two nationwide Dutch trials.

POPULATION

Women with hypertensive disease (HYPITAT trial) or suspected fetal growth restriction (DIGITAT trial) and a Bishop score ≤6.

METHODS

Comparison of outcomes after induction of labour and expectant management.

MAIN OUTCOME MEASURES

Rates of caesarean section and adverse neonatal outcome, defined as 5-minute Apgar score ≤6 and/or arterial umbilical cord pH <7.05 and/or neonatal intensive care unit admission and/or seizures and/or perinatal death.

RESULTS

Of 1172 included women with an unripe cervix, 572 had induction of labour and 600 had expectant management. We found no significant difference in the overall caesarean rate (difference -1.1%, 95% CI -5.4 to 3.2). Induction of labour did not increase caesarean rates in women with Bishop scores from 3 to 6 (difference -2.7%, 95% CI -7.6 to 2.2) or adverse neonatal outcome rates (difference -1.5%, 95% CI -4.3 to 1.3). However, there was a significant difference in the rates of arterial umbilical cord pH <7.05 favouring induction (difference -3.2%, 95% CI -5.6 to -0.9). The number needed to treat to prevent one case of umbilical arterial pH <7.05 was 32.

CONCLUSIONS

We found no evidence that induction of labour increases the caesarean rate or compromises neonatal outcome as compared with expectant management. Concerns over increased risk of failed induction in women with a Bishop score from 3 to 6 seem unwarranted.

TWEETABLE ABSTRACT

Induction of labour at low Bishop scores does not increase caesarean section rate or poor neonatal outcome.

Randomized controlled trials of maternal-fetal surgery: a challenge to clinical equipoise

This article focuses on maternal-fetal surgery (MFS) and on the concept of clinical equipoise that is a widely accepted requirement for conducting randomized controlled trials (RCT). There are at least three reasons why equipoise is unsuitable for MFS. First, the concept is based on a misconception about the nature of clinical research and the status of research subjects. Second, given that it is not clear who the research subject/s in MFS is/are, if clinical equipoise is to be used as a criterion to test the ethical appropriateness of RCT, its meaning should be unambiguous. Third, because of the multidisciplinary character of MFS, it is not clear who should be in equipoise. As a result, we lack an adequate criterion for the ethical review of MFS protocols. In our account, which is based on Chervenak and McCullough's seminal work in the field of obstetric ethics, equipoise is abandoned. and RCT involving MFS can be ethically initiated when a multidisciplinary ethics review board (ERB), having an evidence-based assessment of the risks involved, is convinced that the value of answering the research hypothesis, for the sake of the health interests of future pregnant women carrying fetuses with certain congenital birth defects, justifies the actual risks research participants might suffer within a set limit of low/manageable.

Prediction of neonatal outcome in women with gestational hypertension or mild preeclampsia after 36 weeks of gestation

BACKGROUND

There is little knowledge about neonatal complications in GH and PE and induction at term, we aim to assess whether they can be predicted from clinical data.

METHODS

We used data of the HYPITAT trial and evaluated whether adverse neonatal outcome (Apgar score < 7, pH < 7.05, NICU admission) could be predicted from clinical data. Logistic regression, ROC analysis and calibration were used to identify predictors and evaluate the predictive capacity in an antepartum and intrapartum model.

RESULTS

We included 1153 pregnancies, of whom 76 (6.6%) had adverse neonatal outcome. Parity (primipara OR 2.75), BMI (OR 1.06), proteinuria (dipstick +++ OR 2.5), uric acid (OR 1.4) and creatinine (OR 1.02) were independent antepartum predictors; In the intrapartum model, meconium stained amniotic fluid (OR 2.2), temperature (OR 1.8), duration of first stage of labour (OR 1.15), proteinuria (dipstick +++ OR 2.7), creatinine (OR 1.02) and uric acid (OR 1.5) were predictors of adverse neonatal outcome. Both models showed good discrimination (AUC 0.75 and 0.78), but calibration was limited (Hosmer-Lemeshow p = 0.41, and p = 0.20).

CONCLUSIONS

In women with GH or PE at term, it is difficult to predict neonatal complications, possibly since they are rare in the term pregnancy. However, the identified individual predictors may guide physicians to anticipate requirements for neonatal care.

Impact of introduction of mid-trimester scan on pregnancy outcome of open spina bifida in The Netherlands

OBJECTIVE

To examine the impact of introduction of the mid-trimester scan on pregnancy outcome in cases of open spina bifida in two regions of The Netherlands.

METHODS

This was a retrospective cohort study of 190 cases of open spina bifida diagnosed pre- or postnatally, with an estimated date of delivery between 2003 and 2011.

RESULTS

With implementation of the mid-trimester scan the percentage of cases of open spina bifida detected before the 24(th) week of pregnancy increased from 43% to 88%. The rise in prenatal detection rate was associated with a significant increase in the number of terminated pregnancies and a decrease in the rate of perinatal loss; the percentage of children born alive did not change significantly. In the subgroup that underwent a scan between 18 and 24 weeks of pregnancy, cranial signs were present in 94.4% of cases.

CONCLUSION

Introduction of the mid-trimester scan has led to an increase in early identification of pregnancies complicated by open spina bifida. Pregnancies previously destined to end in perinatal loss are now terminated whilst pregnancies with a relatively good prognosis are frequently continued; the number of children with open spina bifida who are born alive has not changed significantly. Our study confirms that prenatal diagnosis is usually triggered by visualization of a lemon-shaped skull or a banana-shaped cerebellum.

Perceptions of women, nurses, midwives and doctors about the use of video during birth to improve quality of care: focus group discussions

The use of video during birth for quality of care was discussed in focus groups with women, nurses, midwives and doctors. Qualitative analysis revealed three categories of importance. First, goals and benefits: improving quality of care, teaching, research and legal issues are important potential applications. Second, limitations: concerns for privacy, fear of feedback and use of video in case of adverse events. Third, rules and regulations: goals and scope of the use of video need to be clearly described, access to video needs to be secured, and time until destruction needs to be specified. Video capture of birth is considered useful and seems acceptable if specific conditions are met.

Delayed intrauterine repair of an experimental spina bifida with a collagen biomatrix

BACKGROUND/PURPOSE

The aim of the study was to evaluate whether a collagen biomatrix is useful for delayed intrauterine coverage of a surgically created spina bifida in a fetal lamb.

METHODS

In 20 fetal lambs, surgery was performed at 72 or 79 days' gestation. In 15 lambs a spina bifida was created surgically. In 8 lambs it was covered with a collagen biomatrix 2 weeks later and in 7 lambs it was left uncovered. Five lambs served as sham operated controls. Neurological examination was performed at 1 week of age and afterwards the lambs were sacrificed for further histological evaluation.

RESULTS

None of the 5 surviving lambs with the defect covered showed loss of spinal function and the architecture of the spinal cord was preserved in 4 of the 5 lambs. In the uncovered group, 1 of the 4 surviving lambs had loss of spinal function, 5 lambs were available for histological evaluation and 4 of them showed disturbance of the architecture of the spinal cord.

CONCLUSIONS

Collagen biomatrices can be used for intrauterine coverage of an experimental spina bifida and can preserve the architecture of the spinal cord. Neurological outcome is not different between fetuses with their spinal cord covered and fetuses with uncovered cords.

Histological Evaluation of Acute Covering of an Experimental Neural Tube Defect with Biomatrices in Fetal Sheep

OBJECTIVE

The aim of the study was to determine the histological effect on the neural tissue of in utero covering of an experimental neural tube defect in fetal lambs, with the use of two different biomatrices.

MATERIALS AND METHODS

In 23 fetal sheep, surgery was performed at 79 days' gestation. In 19 of these, a neural tube defect was created, while 4 fetuses served as sham-operated controls. In 7 of the 19 operated fetuses the defect was left uncovered. In the remaining 12 animals the defect was covered either with a collagen biomatrix (4 animals), skin (3 animals), or small intestinal submucosa biomatrix (5 animals). The lambs were sacrificed at 1 week of age and histological examination was performed.

RESULTS

All lambs with an uncovered neural tube defect showed histological damage of the spinal cord. In lambs in which the neural tube defect was covered, one half showed a normal architecture of the spinal cord while minor histological damage was present in the other half. Between the three groups in which the defect was covered, the histological outcome was comparable.

CONCLUSIONS

Acute covering of an experimental neural tube defect in fetal lambs prevents severe histological damage to the spinal cord independent of the two biomatrices used in this study.

In utero Repair of an Experimental Neural Tube Defect in a Chronic Sheep Model Using Biomatrices

OBJECTIVE

Persistent exposure of the unprotected spinal cord to amniotic fluid and the uterine wall can lead to progressive damage of neural tissue in case of a myelomeningocele (two-hit hypothesis). The aim of this study was to evaluate whether in utero repair of an experimental neural tube defect in a fetal lamb could protect neural tissue from secondary injury and save neurologic functions after birth.

METHODS

In 19 fetal lambs, a neural tube defect was created at 79 days' gestation. In 12 lambs the defect was covered either with a novel, molecular defined collagen-based biocompatible and biodegradable matrix (UMC) or with a small intestinal submucosa (SIS) biomatrix (Cook) or by closing the skin over the defect.

RESULTS

All lambs with the defect covered showed no or minor neurologic morbidity in contrast to the lambs with the defect uncovered in which major neurologic morbidity was seen.

CONCLUSIONS

These results demonstrate that long-term exposure of the open spinal cord to the intrauterine environment can lead to damage of neural tissue and, consequently loss of neurologic functions and that coverage of the defect can lead to a better neurologic outcome. Furthermore, we could show that a UMC biomatrix and an SIS biomatrix are useful for in utero coverage of a surgically created neural tube defect in our model.

Different pharmacokinetics of tramadol in mothers treated for labour pain and in their neonates

OBJECTIVE

The aim of the present study was to investigate the pharmacokinetic profile of tramadol hydrochloride in neonates, born from mothers who underwent analgesia with tramadol for the relief of labour pain.

METHODS

Intramuscular tramadol (100--250 mg) was administered to 22 mothers giving birth who requested pain relief. At the time of birth (1.5--6.0 h after last tramadol dose), maternal and umbilical blood samples were taken. Another venous blood sample was drawn from each neonate, and at the same time from its mother, at 1, 2, 3, 6 or 12 h post-partum, providing the data for a population pharmacokinetic evaluation of tramadol and its metabolite M1. Routine APGAR scores and a standard neurological and adaptive capacity test were considered for evaluation of the effect of tramadol on the neonates.

RESULTS

Serum tramadol concentrations at the time of birth (t(0)) were 243+/-102 ng/ml (mean+/-SD, umbilical vein), 258+/-103 ng/ml (umbilical artery) and 250+/-113 ng/ml (maternal vein). Serum M1 concentrations were 52+/-27 ng/ml (umbilical vein), 47+/-24 ng/ml (umbilical artery) and 56+/-21 ng/ml (maternal vein). The two-compartment type elimination profiles during the first 12 h post-partum for neonates (and mothers, respectively) were characterised by terminal t(1/2) (tramadol)=7.0 (7.2) h and t(1/2) (metabolite M1)=85.0 (5.5) h.

CONCLUSION

The intramuscular application of tramadol in birth-giving mothers almost freely reaches the neonate, confirming a high degree of placental permeability. The neonates already possess the complete hepatic capacity for the metabolism of tramadol into its active metabolite. However, the renal elimination of the active tramadol metabolite M1 is delayed, in line with the slow maturation process of renal function in neonates. Despite this difference in pharmacokinetics between neonates and adults, the intramuscular application of tramadol at the recommended dosage range during delivery appears to effective in the relief of labour pain.

[Perinatal asphyxia as incorrect explanation for mental retardation]

Three women, aged 21, 34 and 32 and with a family history of mental retardation said to be caused by perinatal asphyxia, each gave birth to a child with mental retardation. A chromosomal translocation, fragile X syndrome, and myotonic dystrophy could be diagnosed, respectively. In retrospect, the diagnosis of perinatal asphyxia in the family history had been too readily accepted. In reality the mental retardation was caused by a genetic disorder. Physicians are used to making a diagnosis, and when a diagnosis is not (yet) possible, they try to establish a working diagnosis or differential diagnosis. Too often such a working diagnosis becomes, through time, a definite diagnosis.

Metabolic information from the human fetal brain obtained with proton magnetic resonance spectroscopy

OBJECTIVE

To study the feasibility of proton magnetic resonance spectroscopy for the examination of human fetal brain metabolism.

STUDY DESIGN

Proton magnetic resonance spectroscopy was performed from a selected volume of brain tissue of 21 single normal fetuses of 36 to 41 weeks' gestational age. Absolute brain metabolite tissue levels were estimated by using the brain water content as an internal reference.

RESULTS

Proton magnetic resonance spectra showed resonances for four dominating brain metabolites. Inositol, choline, creatine, and N-acetylaspartate could be detected with average tissue levels of 7.42 mmol/L, 3.31 mmol/L, 4.16 mmol/L, and 5.03 mmol/L, respectively. The resonance for N-acetylaspartate could not always be resolved from contaminating lipid signals.

CONCLUSION

Proton magnetic resonance spectroscopy of the human fetal brain is feasible and can provide useful information about the fetal condition. The metabolite tissue levels for the fetal brain obtained in this study were in the range observed for neonates of similar gestational age.

[Physical diagnostics--auscultation of fetal heart sounds]

Auscultation or recording of foetal heart tones is possible throughout pregnancy. In the first trimester, the presence of heart activity proves a vital pregnancy and reduces the probability of spontaneous abortion. From the end of the second and during the whole of the third trimester foetal heart activity can be used to asses the foetal condition. The introduction of cardiotocography failed to reduce serious perinatal morbidity or mortality as compared with intermittent auscultation, but did increase the number of obstetrical interventions.

Risk for surviving twin after fetal death of co-twin in twin-twin transfusion syndrome

OBJECTIVE

To determine neonatal outcome of surviving twins in pregnancies complicated by twin-twin transfusion syndrome and fetal deaths of co-twins.

METHODS

We retrospectively reviewed medical records of 11 women seen during 1990-1996 in our hospital who had pregnancies complicated by twin-twin transfusion syndrome and death of one fetus.

RESULTS

The median interval between fetal death and delivery (six by cesarean delivery and five vaginally) was 2 weeks (range, 1 day to 7 weeks). Three of the 11 surviving twins died soon after birth (gestational ages at birth 32, 31, and 34 weeks; fetal death-delivery intervals 3, 7, and 7 weeks, respectively). Two survivors were severely handicapped (gestational ages at birth 29 and 33 weeks; fetal death-delivery interval 1 and 2 weeks, respectively). Two children showed cerebral echodensities on ultrasound after birth but developed normally, and four did not show any abnormalities on cerebral and abdominal ultrasound and developed normally. Five of 11 surviving twins, each born 1 week or more after fetal death of the co-twin, either died or experienced serious morbidity. In the two infants born within 1 day of fetal death, no problems were detected.

CONCLUSION

In monochorionic twin gestations complicated by twin-twin transfusion syndrome, approximately half of surviving twins will experience mortality or serious morbidity when co-twins die in utero.

[Circulatory arrest following sulprostone administration in postpartum hemorrhage]

In a woman aged 39 cardiac arrest occurred 3.5 hours after administration of 250 micrograms sulprostone directly into the uterine wall for a post-partum haemorrhage after manual removal of the placenta. A long period of resuscitation was necessary. After further evaluation the woman demonstrated specific contraindications to the administration of sulprostone. as formulated by the French authorities: age > 35 years, heavy cigarette smoking, and cardiovascular risk factors. In the Netherlands sulprostone is registered for intravenous administration only. We would strongly advise against administration directly into the uterine wall.

The efficacy of intrapartum fetal surveillance when fetal pulse oximetry is added to cardiotocography

OBJECTIVE

To determine if oxygen saturation measurement with pulse oximetry (SpO2) in combination with cardiotocograghy (CTG), improves the assessment of the intrapartum fetal condition.

STUDY DESIGN

Four expert obstetricians individually evaluated 119 cases that were monitored during labor: during the first session the CTG data were available, and in the second session CTG and SpO2 data were evaluated. They were instructed to indicate the need for intervention and to estimate the umbilical artery pH.

RESULTS

In the non-acidotic group (umbilical artery pH > or = 7.15, n = 112) the average(+/-S.D.) number of interventions decreased from 27(+/-17) to 16(+/-9) when SpO2 was available. This reduction in number of interventions resulted in an significantly increased specificity for two referees. In the acidotic group (n = 7) the average number of interventions also decreased, from 6(+/-2) to 4(+/-2), and as a consequence the sensitivity decreased. The pH estimate based on CTG + SpO2 was higher in both acidotic and non-acidotic fetuses than the estimated pH based on CTG alone.

CONCLUSION

In this study all referees intervened less frequently when SpO2 was used as an adjunct to CTG. This resulted in fewer unnecessary operative interventions, but may also lead to unidentified fetal acidosis. The number of acidotic newborns (n = 7) was too small, however, to draw definite conclusions. Larger studies should address the efficacy of SpO2 in detecting fetal compromise before clinical use can be advocated.

Neonatal complications in newborns with an umbilical artery pH < 7.00

OBJECTIVE

Our purpose was to determine the significance of an umbilical artery pH < 7.00 in relation to neonatal morbidity and mortality.

STUDY DESIGN

Between 1986 and 1993 acid-base assessment of the umbilical artery was performed routinely in 10,699 deliveries. In a retrospective cohort study 84 nonanomalous neonates with an umbilical artery pH < 7.00 were individually matched with 84 neonates with an umbilical artery pH > 7.24. Matched variables included year of delivery, gender, parity, maternal age, delivery mode, fetal presentation, gestational age, and birth weight. Differences in morbidity between the two groups during the neonatal period (until 28 days after delivery) were investigated.

RESULTS

Neonates with an umbilical artery pH < 7.00 versus > 7.24 showed significant differences in the following: neonatal condition directly post partum; neurologic, respiratory, cardiovascular, and gastrointestinal complications; and neonatal intensive care unit admissions. No significance was found in renal dysfunction and mortality rate. The proportion of premature infants (< 37 weeks) was 17% in both groups. In the acidotic group a 1-minute Apgar score < or = 3 and a 5-minute Apgar score < 7 was predictive for neonatal complications.

CONCLUSIONS

Severe intrapartum asphyxia, quantified by an umbilical artery pH < 7.00, poses a threat to the neonate's health.

The effect of pulsating arteries on reflectance pulse oximetry: measurements in adults and neonates

OBJECTIVE

The objective of our study was to describe the results from human experiments during normoxia that demonstrate the effect of pulsating arteries on the measured arterial oxygen saturation (SpO2) using a reflectance pulse oximeter sensor.

METHODS

In 6 healthy adults and 7 healthy neonates, a Nellcor reflection sensor (FS-10 oxisensor, Nellcor, Inc., Pleasanton, CA) was placed in three different positions: (1) on the forehead, (2) on the temporal area, with the photodiode placed over the superficial temporal artery, and (3) on the temporal area, with the light-emitting diodes (LEDs) placed over the superficial temporal artery.

RESULTS

Placement of the sensor in position 2 resulted in a significantly lower SpO2 reading, compared to sensor position 1: 5.8% (p < 0.01) lower for adults and 7.5% (p < 0.01) lower for neonates. Placement of the sensor in position 3 resulted in significantly larger plethysmographic signals, compared to sensor position 1; but, the Spo2 readings were alike.

CONCLUSIONS

Pulsating arteries can affect the reliability of reflection pulse oximetry. Depending on the position of the sensor, a falsely low Spo2 value can be observed.

Arterial oxygen saturation in relation to metabolic acidosis in fetal lambs

OBJECTIVE

We studied the relationship between preductal arterial oxygen saturation and metabolic acidosis in 18 chronically instrumented fetal lambs (gestational age 119 to 133 days) in two experimental designs. In the first group the onset of metabolic acidosis was determined. In the second group the progression of metabolic acidosis was studied as was the cardiovascular and hormonal changes resulting from hypoxemia.

STUDY DESIGN

In nine fetal lambs maternal fraction of inspired oxygen was lowered stepwise by increasing flows of nitrogen delivered into the trachea through a small indwelling catheter (group 1), and in nine fetal lambs maternal blood flow was reduced stepwise by means of a vascular occluder (group 2).

RESULTS

Baseline arterial oxygen saturation values ranged from 26% to 67% with normal pH and extracellular fluid base excess values in both groups 1 and 2. In both groups pH and extracellular fluid base excess started to decrease below 30% arterial oxygen saturation, with a progressive decrease below 20% arterial oxygen saturation to an end value for pH of 7.14. In some fetal lambs pH and extracellular fluid base excess decreased initially at 20% to 30% arterial oxygen saturation and then stabilized at the lower level. Fetal heart rate in group 1 increased during hypoxemia from 155 to 179 beats/min. In group 2 baseline fetal heart rate was 153 beats/min and fell with every step change in arterial oxygen saturation but subsequently increased to 172 beats/min by the end of the period of hypoxemia. Baseline values for epinephrine, norepinephrine, dopamine, cortisol, and mean arterial pressure were not related to baseline arterial oxygen saturation levels, and each of these variables was increased at the end of hypoxemia in group 2.

CONCLUSION

Preductal arterial oxygen saturation can reach values between 20% and 30% before anaerobic metabolism starts. During the progressive acidosis blood pressure was increased, which can be attributed to a strong rise in catecholamines.

Intrapartum fetal surveillance of congenital heart block with pulse oximetry

BACKGROUND

In cases of fetal congenital heart block, the fetal heart rate (FHR) pattern is uninterpretable, often leading to an operative delivery. Reflectance pulse oximetry, a new technique that continuously measures the fetal arterial oxygen saturation (SaO2) during labor, is potentially useful in intrapartum monitoring of fetuses with this condition.

CASES

Two fetuses with congenital heart block were monitored with reflectance pulse oximetry and fetal scalp blood sampling. The first patient delivered spontaneously. Adequate signal quality was achieved during 73% of the study time. Mean +/- standard deviation (SD) SaO2 was 53 +/- 14%. Fetal outcome was good. The second patient was delivered by cesarean because of arrest of labor. Oxygen saturation values were obtained during 89% of the study time. The mean SaO2 was 42 +/- 13%. There was a period of 8 minutes with SaO2 values below 20%. Capillary blood pH dropped from 7.33 to 7.25; SaO2 values then returned to levels above 30% and the capillary blood pH normalized. The neonate was born in good condition.

CONCLUSION

In fetal congenital heart block, adequate surveillance with FHR monitoring during labor is not possible; therefore, continuous information on fetal oxygenation may be valuable in assessing the fetal condition and may prevent unnecessary obstetric interventions.

Intrapartum fetal pulse oximetry: fetal oxygen saturation trends during labor and relation to delivery outcome

OBJECTIVES

Our purpose was to study fetal arterial oxygen saturation trends by continuous pulse oximetry during labor in subjects with normal and abnormal delivery outcomes.

STUDY DESIGN

Continuous fetal arterial oxygen saturation was measured during labor with a noninvasive reflectance pulse oximeter designed for fetal application. Averaged arterial oxygen saturation values were compared between stage 1 and stage 2 of labor, with stage 1 further subdivided into early (< or = 4 cm), middle (5 to 7 cm), and late (8 to 10 cm) phases. Delivery outcome was considered to be abnormal for any of the following conditions: gestational age < 37 weeks, maternal oxygen administration, delivery by cesarean section, 5-minute Apgar score < 7, umbilical artery pH < 7.10, birth weight < 2500 gm, or newborn intensive care unit admission.

RESULTS

A total of 291 subjects were studied: 142 in Provo, 90 in Nijmegen and 59 in San Francisco. Subjects with delivery complications (n = 125) were evaluated separately from those with normal delivery outcomes (n = 160). Fetal arterial oxygen saturation was 58% +/- 10% (mean +/- SD) during the cumulative period of study for the normal-outcome group. A significant decrease (paired t test, p < 0.001) in fetal arterial oxygen saturation occurred from stage 1 (59% +/- 10%) to stage 2 (53% +/- 10%) labor. When stage 1 was subdivided into early (< or = 4 cm), middle (5 to 7 cm), and late (8 to 10 cm) phases, a gradual decreasing trend in fetal arterial oxygen saturation was observed: 62% +/- 9%, 60% +/- 11%, and 58% +/- 10%.

CONCLUSIONS

With the use of reflectance pulse oximetry, a statistically significant decrease in fetal arterial oxygen saturation was observed during labor in women with normal and abnormal delivery outcomes.

The ductus arteriosus, pre- and post-ductal oxygen saturation measurements in fetal lambs

In the fetus, the arterial oxygen saturation (SaO2) in the ascending aorta is higher than in the descending aorta. We questioned whether this difference over the ductus arteriosus (delta SaO2) would change during hypoxaemia. Therefore, six chronically instrumented fetal lambs (119-126 days of gestation) were studied, by changing the inspired oxygen (FIO2) via a tracheal tube to the ewe. The SaO2 was measured intermittently every 15 min with blood samples obtained from the ascending and descending aorta, and continuously with 2 pulse oximeters at both sides of the ductus arteriosus. delta SaO2 was at a level of 3.4-5.3% and had a tendency to decrease at preductal SaO2 levels of 10-20% and at pH levels below 7.25. The precision of the pulse oximeters, expressed as standard deviation of the differences between sample SaO2 and pulse oximeter SaO2, was around 5.0% for the individual calibration curves. This precision was not enough to show details of the course of delta SaO2 between the blood samples. Our results show that there is no change in delta SaO2 across the ductus arteriosus.

Proton magnetic resonance spectroscopy of human fetal brain

In vivo proton magnetic resonance spectroscopy of human fetal brain was performed in the third trimester of pregnancy. Spectra were obtained showing signals assigned to cerebral compounds such as N-acetylaspartate, creatine, and cholines. Relative signal intensities were similar to those observed in neonatal brain spectra recorded during the early postnatal stage.

Fetal transcutaneous PCO2 measurements during labour

The departments of Obstetrics and Gynaecology of the Universities of Bonn and Copenhagen and the Free University of Amsterdam cooperated in the European Community Concerted Action Project 'New methods for Perinatal Surveillance'. In 95 patients fetal transcutaneous PCO2 (tcPCO2) recording (measuring temperature 41 degrees C) during labour was evaluated regarding its clinical applicability. During the first stage of labour fetal tcPCO2 was rather stable at a level of 7.3 +/- 1.4 kPa. In the second stage there were marked differences between the three subpopulations. In the first stage of labour the correlation between tcPCO2 and PCO2 in fetal blood samples was 0.38 (P = 0.02) and in the second stage -0.20 (P = 0.36). The correlation of fetal tcPCO2 with umbilical artery PCO2 was 0.30 (P = 0.01) and with pH -0.30 (P = 0.01). Using a fetal tcPCO2 level of 8.0 kPa as a cut-off point to predict an umbilical artery pH less then 7.20, sensitivity was 88%, specificity 65%, positive predictive value 29% and negative predictive value 97%. The likelihood ratio of a positive test was 2.47 and of a negative test 0.13. It is concluded that fetal tcPCO2 possibly can be an additional tool to exclude fetal acidosis. In case of values above 8.0 kPa further evaluation of the fetal acid-base balance is indicated.