REVIEW

Antepartum fetal healthJacqueline CK Tsang

Nia Wyn Jones

Abstract

Delivery of a healthy full term baby following an uneventful antenatal

period occurs in the majority of pregnancies. These are classified as a

low-risk pregnancy group. There are, however, some pregnancies that

are complicated due to maternal or fetal disease that can increase the

risk of perinatal morbidity and mortality. This is classified as a high-risk

group. The aim of fetal surveillance is to identify these threatened fetuses

with the prospect of altering the timing of delivery to prevent the worst

outcome, stillbirth. This article looks at the tools available to assess ante-

natal fetal health in all pregnancies and their ability to identify the at-risk

pregnancies that require extra surveillance to improve outcomes. This

article does not address fetal surveillance during labour.

Keywords amniotic fluid index; biophysical profile; cardiotocography;

customized growth chart; middle cerebral artery Doppler; symphysis-

fundal height; ultrasound biometry; umbilical artery Doppler; uterine ar-

tery Doppler; venous Doppler

Introduction

The aim of midwives and obstetricians is to identify those preg-

nancies considered high-risk, due to numerous circumstances

(maternal disease, fetal pathology, placental pathology or intra-

partum complications), and provide a level of support necessary

to take these pregnancies to healthy positive outcomes. In doing so,

there is an increased need formonitoring in the pregnancy. The aim

for undertaking thismonitoring is to reduce perinatalmorbidity and

mortality and to identify the ideal timing for delivery to achieve the

most successful outcome. The vast majority of pregnancies, how-

ever, are considered low-risk and result in a healthy term delivery.

As a result of this and the fact that pregnancy is a normal physio-

logical process it should be central that any intervention should be

beneficial and acceptable to pregnant women. This review looks at

the surveillanceoptions available for low-riskpregnancies aswell as

methods used when a pregnancy is deemed high-risk. This article

does not address fetal surveillance during labour ormanagement of

established complications like pre-eclampsia or growth restriction.

Assessment of risk and surveillance strategies

The RCOG recommends that all women undergo an assessment

of risk factors for growth restriction at the time of booking to

Jacqueline CK Tsang MBBS is a Specialist Registrar in Obstetrics and

Gynaecology, City Hospital Campus, Nottingham University Hospitals

NHS Trust, UK. Conflicts of interest: none declared.

Nia Wyn Jones MBBCh MRCP MCROG PhD is an Associate Professor of

Obstetrics and Gynaecology at the University of Nottingham, UK.

Conflicts of interest: none declared.

OBSTETRICS, GYNAECOLOGY AND REPRODUCTIVE MEDICINE 24:3 80

allow increased surveillance in those at-risk. They have defined

risk factors as either major or minor (Table 1) on the basis of the

risk of a small for gestational age (SGA) baby. SGA is defined as

weight less than a specified percentile (in this case the 10th

percentile). Major risks have an odds ratio (OR) of greater than

2.0 for SGA whilst minor risks have an OR of less than 2. The

presence of one major risk factor should prompt referral, from 26

to 28 weeks gestation, for serial USS measurements of fetal size

and growth together with umbilical artery Doppler for fetal

wellbeing. Uterine artery Doppler assessment at 20e24 weeks

should be offered in the presence of three or more minor risk

factors. Those women with abnormal values should also be

offered serial USS assessments of growth and wellbeing, whilst a

single third trimester assessment of fetal size and umbilical artery

Doppler is recommended if the uterine artery Doppler is normal.

The final group who should be offered serial growth surveillance

is where the SFH measurement is considered to be flawed e.g.

body mass index (BMI) >35 kg/m2, large fibroids or abnormal

liquor volume.

Low-risk pregnancy

It is recommended in NICE guidelines in an uncomplicated

singleton pregnancy that there should be ten scheduled antenatal

appointments for nulliparous women and seven for multiparous

women. Reducing the number of antenatal visits reduces

women’s satisfaction of the care provided. A review of the

antenatal care pathway in middle- and low-income countries,

where the number of visits in a standard pathway may already be

limited, also suggested a 15% increase in perinatal mortality with

reduced antenatal care visits. For high income countries perinatal

mortality was low (0.6% overall compared to 2% in low-income

countries) limiting the power of the study- no clear difference

between the two pathways was evident.

The first appointment should preferably be prior to 10 weeks’

gestation in order to identify risk factors in the pregnancy and

schedule a dating scan to accurately determine the estimated date

of confinement for which all further appointments and tests will

be related/compared to. Failure to assign an accurate gestational

age will make the precise diagnosis of a SGA baby difficult. Ul-

trasound based establishment of gestational age is also important

for reducing the number of post term inductions, as using the last

menstrual period to calculate confinement dates has inaccuracies

of between 11 and 42%. Throughout their pregnancy women

should be given information that is easy to understand, is ac-

curate, balanced and based on current evidence. This is to allow

women to make informed choices about the care they receive

throughout pregnancy (Box 1).

Antepartum assessment of fetal health aims

C To prevent the death of the fetus

C To optimize the timing of delivery, minimizing fetal and neonatal

morbidity

C To avoid unnecessary intervention (e.g. pre-term delivery) if fetal

health is confirmed

Box 1

Crown Copyright � 2014 Published by Elsevier Ltd. All rights reserved.

Risk factors for a SGA neonate (adapted from the RCOG‘Investigation and management of SGA fetus’ guideline)

Category Major risk factors

(OR >2.0 for SGA)

Minor risk factors

(OR<2.0)

Booking

history

Maternal age >40 years

Smoker �11 cigarettes/

day

Cocaine use

Daily vigorous exercise

Maternal SGA

Paternal SGA

Maternal age �35 years

Smoker 1e10 cigarettes/

day

Nulliparity

BMI<20 kg/m2

BMI 25e30 kg/m2

Low fruit intake pre-

pregnancy

Previous

pregnancy

Previous SGA

Previous stillbirth

Previous pre-eclampsia

Pregnancy interval <6

months or �30 months

Maternal

medical

history

Chronic hypertension

Diabetes and vascular

disease

Renal impairment

Antiphospholipid

syndrome

Current

pregnancy

Threatened miscarriage

with vaginal bleeding

similar to period

Pre-eclampsia

Severe pregnancy induced

hypertension

Unexplained APH

Low maternal weight gain

PAPP-A <0.4 MoM

Echogenic bowel

IVF singleton pregnancy

Table 1

REVIEW

Measuring symphysis-fundal height (SFH)

This is a lowcost, easily performedmethodof fetal surveillancewith

the operator using a tapemeasure to identify the uterine fundus and

symphysis pubis and taking ameasurement of the distance between

the two points. The aim of measuring SFH in antenatal surveillance

is to identify those fetuses at-risk of being SGA.

However, of the fetuses identified below the 10th centile on

growth charts, who are labelled as SGA, 50e70% of them are

actually constitutionally small fetuses. These fetuses are appro-

priately sized in relation to parental body mass index, ethnicity

and parity. They are not at higher risk of perinatal morbidity and

mortality. In contrast, fetuses with growth restriction fail to reach

their genetic growth potential due to a tail off in fetal growth.

These fetuses are at higher risk of perinatal morbidity and mor-

tality. The SFH measurement will not detect a fetus that is growth

restricted but above the 10th centile.

Palpation of the abdomen alone has a sensitivity of 21% and

specificity of 96% for the detection of SGA fetuses and should not

be routinely used for this purpose. The addition of SFH mea-

surement makes little alteration in prediction, with a sensitivity

and specificity of 27% and 88% respectively, although studies

vary widely in the predictive accuracy quoted. The addition of

OBSTETRICS, GYNAECOLOGY AND REPRODUCTIVE MEDICINE 24:3 81

serial measurements may improve the sensitivity and specificity

of this test by allowing changes in the rate of growth to be

observed, particularly for repeated measurements by the same

individual.

In the UK NICE recommend, at every antenatal appointment

after 24 weeks, the SFH is measured and plotted on growth charts

to identify fetuses crossing growth centiles and/or fetuses below

the 10th centile on a single SFH measurement. These women

should be referred on for further assessment of growth with the

use of ultrasound.

Although there are concerns that there is inter-operator vari-

ability using this technique, its low cost and requirement of

minimal time, training and equipment make it a valuable

screening method, especially in low-income countries where ul-

trasound resources are greatly limited. There are also concerns

that SFH measurement is inaccurate in women with raised BMI

(>35 kg/m2) and USS assessment of fetal size may be more

appropriate for surveillance in this group. In low-risk pregnan-

cies ultrasound assessment of fetal size is not recommended for

suspected large for gestational age fetuses by SFH measurement.

Customized growth charts

When plotting SFH measurements, customized growth charts

adjusting for maternal height, weight, parity, ethnicity, and other

physiological variables have been suggested in an attempt to

improve the identificationof SGA fetuses.ACochraneCollaboration

review of using customized versus population growth charts

demonstrated better identification of SGA fetuses with the former

method (relative risk: RR 0.74). This however did not translate to

betterperinatal outcomes.Therewasno randomizedcontrolled trial

evidence comparing population to customized growth charts e

evidencewas derived fromanobservational cohort study. Themost

up-to-date RCOG guidelines recommend use of customized growth

charts to aid in prediction of SGA babies.

Auscultating fetal heart

Routine auscultation of the fetal heart at appointments is not

recommended in current NICE guidelines. Fetal wellbeing cannot

accurately be predicted with the use of fetal heart auscultation as

it cannot detect subtle variations in beat-to-beat variability or, on

a larger scale, fetal accelerations and decelerations which could

be demonstrated on a continuous cardiotocograph monitor. NICE

guidelines state that it may be performed for reassurance of the

mother, on her request, although it may also increase anxiety if

detection is protracted.

Ultrasound biometry

In the low-risk population a Cochrane review (n ¼ 27,024) found

no improvement in perinatal mortality and no difference in ob-

stetric interventions (including induction of labour, instrumental

deliveries) or neonatal measures (Apgar scores, NNU admission)

in women who underwent third trimester fetal biometry by ul-

trasound compared to those that did not. Therefore routine third

trimester USS is not recommended in this group by the Cochrane

review or current RCOG guidelines.

High-risk pregnancy

The aim of assessing the fetus in the antenatal period is to

identify those fetuses at-risk of developing complications such as

Crown Copyright � 2014 Published by Elsevier Ltd. All rights reserved.

REVIEW

growth restriction and to ultimately reduce the risk of perinatal

mortality and morbidity by modifying and individualizing care.

Monitoring fetal movements

Monitoring for fetal movements is a mother’s most basic way of

assessing fetal activity/life. It is noted that reduced or no fetal

movements can be a sign of imminent fetal death in utero. This is

due to chronic fetal hypoxia resulting in reduced fetal movement

in an attempt to reduce oxygen consumption. Evidence from

meta-analysis suggests formal fetal movement counting using

kick charts is not recommended for monitoring in the antenatal

period as it failed to show improvement in perinatal outcome.

False reassurance or inappropriate interpretation of additional

tests (e.g. CTG) may be a confounding factor in the failure of this

formal monitoring method to reduce the number of stillbirths in

both low- and high-risk groups. Additionally, failure of the

assessment tools may be related to their low positive predictive

value: 1250 pregnancies would have to be formally monitored in

order to prevent one fetal death in a low-risk pregnancy. How-

ever, the perception of reduced fetal movements by the mother

should not be ignored but should trigger further less subjective

forms of surveillance of fetal wellbeing.

Cardiotocography (CTG) and computerized CTG

This can usually be performed from approximately 26 weeks

gestation onwards and consists of an electronic recording, traced

onto a paper strip, of maternal uterine activity and the fetal heart

rate, monitored via an ultrasound transducer placed on the

woman’s abdomen. The four variables scrutinized in CTG

monitoring are: 1. baseline rate, 2. variability, 3. accelerative

episodes and 4. decelerations. This is assessed alongside the

presence and timing of uterine contractions. Reassuring values

for a fetus beyond 26 weeks, over a 20 minute period, include a

baseline rate between 110 and 160 beats per minute, a variability

between 5 and 25 beats per minute, a greater than 15 beats per

minute increase from the baseline for greater than 15 seconds

(accelerations), and absence of greater than 15 beats per minute

decrease from the baseline for greater than 15 seconds (de-

celerations). A normal fetal heart rate varies with vagal and

sympathetic tone as well as gestational age, whilst hypoxia

additionally leads to reduction in the baseline variability, accel-

erations to be reduced or absent and decelerations may occur.

CTG changes occur very late in the disease process of FGR,much

later than Doppler abnormalities, making their use in the ante-

partumassessment of fetal health of limitedvalue.Whenemploying

CTG recordings to detect fetal compromise there is a lack of speci-

ficity for this conditionandhigh falsepositive rates. Interpretationof

antepartum CTGs within and between observers can also display

poor reliability and scoring systems have failed to help.

Antepartum CTG is not recommended in low-risk women e

there are no trials supporting its use. In high-risk women studies

reviewed in the Cochrane Collaboration demonstrated that CTG

use did not result in significant reduction in perinatal mortality

(relative risk: 2.05). The main flaw in this analysis is that it is

underpowered due to low numbers (n ¼ 1627). Therefore there is

a lack of evidence to support use of routine antenatal CTG in

either high- or low-risk groups. The RCOG guidelines state that

evidence suggests CTGs should not be used as the only form of

surveillance in SGA babies.

OBSTETRICS, GYNAECOLOGY AND REPRODUCTIVE MEDICINE 24:3 82

Newer technology has produced analysis systems allowing for

computerized evaluation of CTG recordings. These are thought to

increase objectivity and reliability in the diagnostic information

provided and reduces inter-observer variability compared to

using visual assessment of CTG recordings alone. Computerized

analysis systems are better at predicting fetal acidaemia, hyper-

carbia, and low Apgars due to its improved accuracy in inter-

preting the short term variability (<3.5 ms) in fetal heart rate. In

a small study of 469 high-risk women, there was significant

reduction in perinatal mortality (RR: 0.20) with use of comput-

erized versus traditional CTG. However, due to the underpow-

ered study, further studies are necessary to assess use of

computerized CTG in high-risk pregnancies. RCOG guidance

states when interpreting a CTG, computerized analysis of short

term fetal heart variability is the most useful measure.

Ultrasound biometry and estimated fetal weight

Placental dysfunction results in a reduction in the nutrient supply

to the fetus. Whilst the blood supply to the vital organs of the

heart and brain are maintained, adaptation occurs with mobili-

zation of glycogen stores from the liver and a reduction in blood

flow to, and growth of, non-vital organs like the gut, liver and

kidneys. The most sensitive USS biometric measurements in

predicting FGR is a reduced (<10% centile) abdominal circum-

ference (AC) or estimated fetal weight (EFW). Formulae have

been devised to calculate an EFW which measure parameters

including biparietal diameter, femur length, abdominal and head

circumference. Hadlock’s formula may be the most appropriate

for SGA fetuses. As growth is a dynamic process, serial mea-

surements may further improve prediction; growth is sequen-

tially reduced in FGR but maintained in SGA. Serial growth

measurements should ideally be performed with a minimum

interval of 3 weeks to minimize false positive rates of diagnosis

of FGR. Similar to SFH measurements, customized AC or EFW

charts have also been developed and improve prediction of poor

pregnancy outcome (stillbirth, neonatal death, low Apgar scores

at 5 minutes) in SGA babies.

Amniotic fluid measurements

Fluid produced by the fetus is termed amniotic fluid; it provides a

supportive environment for the fetus to mature and move. It is a

reflection of perfusion in the fetal kidney secondary to its relation

to urine production- in FGR there is redistribution of blood flow

towards the brain and heart with consequent reduction in renal

blood flow and subsequent reduction in amniotic fluid. Amniotic

fluid volume can also be affected by other factors, such as

maternal diabetes, ruptured membranes, structural renal prob-

lems or swallowing disorders in the fetus. Ultrasonography to

measure the level of fluid around the fetus can be used as a

measurement of fetal wellbeing. There are two ways of

measuring the amniotic fluid volume with ultrasound: firstly, the

largest vertical pocket (or pool depth) of amniotic fluid; or sec-

ondly, the amniotic fluid index (AFI), defined as the sum of each

vertical pocket of amniotic fluid from four quadrants of the

uterus. Reduced fluid level, oligohydramnios, is defined as a pool

depth, less than 2 cm or AFI less than 5 cm. Although there is

poor correlation between these measurements and true amniotic

fluid volume, oligohydramnios can be associated with perinatal

morbidity and mortality. The predictive value oligohydramnios

Crown Copyright � 2014 Published by Elsevier Ltd. All rights reserved.

REVIEW

in isolation (normal uterine artery Doppler and normal growth)

for poor outcome is uncertain.

A Cochrane review compared AFI to deepest vertical pool (n ¼3226): results suggest that the rate of diagnosis of oligohydramnios

(RR 2.4) and rates of intervention, such as induction of labour (RR

1.9) and caesarean section for fetal distress (RR 1.5) was higher

when AFI was used to measure amniotic fluid volume. There was,

however, no difference betweenmethods in termsof the peripartum

outcomemeasures of admission to the neonatal unit, Apgar scores,

umbilical artery pH less than 7.1 or presence of meconium. The

reduced numbers diagnosed with oligohydramnios without change

in perinatal morbidity and mortality led the authors to recommend

that the single deepest vertical pool should be used as a predictor of

antenatal fetal wellbeing, although they also suggest a diagnostic

accuracy study of the two methods.

Doppler studies

The use of Doppler ultrasound technology allows one to assess

maternal uterine and fetal circulations. Clinically, this can be

expressed as a pulsatility or resistance index based on calcula-

tions between systolic and diastolic velocities.

Uterine artery Doppler: uterine artery Doppler is utilized to

predict pregnancy complications: pre-eclampsia or FGR.

Abnormal uterine artery Doppler indices at 24 weeks has been

found to have poor accuracy in the prediction of FGR in low-risk

pregnancies and is not justified, whereas in high-risk pregnancies

the prediction rates are moderate for severe FGR. The test has

low sensitivity in the first trimester and is therefore not recom-

mended; assessment should be performed between 20 and 24

weeks. Abnormal results (PI >95th centile or notching) should

result in serial ultrasound biometry and umbilical artery Doppler

assessments. There is no value to repeating the uterine artery

Doppler results in later pregnancy. It must also be remembered

that uterine artery Doppler assessment is a screening test for risk

and not an assessment of antepartum fetal health, so has no role

in the management of fetuses with established FGR.

Umbilical artery Doppler: this is primarily a test of placental

function. With normal placental function, there is forward flow

through to the umbilical artery, in both systole and diastole, in a

low resistance blood flow system. For a decrease in umbilical

artery end diastolic velocity to occur approximately 30% of a

placenta has to be damaged or up-to 70% for reversed end dia-

stolic flow. Sequentially, the patho-physiological consequence is

for a raised umbilical Doppler to progressively lead to absent

then a reversed diastolic flow.

The use of umbilical artery Doppler has been researched in

both low- and high-risk pregnancy populations. Interventional

studies have shown no reduction in perinatal morbidity and

mortality in low-risk pregnancies to predict SGA fetuses. Um-

bilical artery Doppler measurements are, however, useful for

surveillance in high-risk (FGR) pregnancies and should be the

primary surveillance tool. In observational studies this test has

been shown to predict fetal death (Likelihood ratio: LR þ 4.4)

and acidaemia (LR þ 2.8). Interventional studies in this group

also show that it reduces perinatal mortality (1 in 203 women

scanned), antenatal admission (RR 0.72), induction of labour (RR

0.89) and caesarean section (RR 0.90).

OBSTETRICS, GYNAECOLOGY AND REPRODUCTIVE MEDICINE 24:3 83

Observational studies have shown that placental function and

outcomes progressively deteriorate as Doppler waveforms evolve

from positive to absent to reversed end diastolic flow. This

equates to a perinatal mortality of 4 and 10.6 times higher in

absent and reversed end diastolic flow, respectively, when

compared to positive end diastolic flow. Surveillance in high-risk

groups can aid timing of delivery to improve outcomes.

Middle cerebral artery (MCA)Doppler: the fetusadapts toplacental

dysfunction and chronic hypoxaemia by redistribution of well

oxygenatedblood to themost essential bodyorgans such as the brain

and heart. This is known as the brain sparing effect. It does this by

cerebral vasodilatation that is characterized by low resistance blood

flow in the MCA as demonstrated by a low MCA pulsatility index.

An abnormal MCA Doppler is an early sign of fetal hypoxia in

FGR. RCOG guidelines declare it to have limited accuracy to

predict acidaemia in pre-term FGR and should not be used to

time delivery. However, its predictive value is improved after 32

weeks gestation and can help with timing of delivery in term SGA

with normal umbilical artery Doppler. In this group MCA

Doppler PI less than the 5th centile is predictive of caesarean

section and neonatal acidosis (OR 9).

Fetal venous Doppler (ductus venosus, umbilical vein pulsa-

tions): a normal triphasic venous Doppler reflects cardiac after-

load, compliance, and contractility; atrial systole (a-wave) should

always demonstrate forward flow in the ductus venosus. Other

veins may demonstrate physiological reversal. Cardiac decom-

pensation and dysfunction, due to hypoxia of the myocardial tis-

sue is characteristic of the end stage of placental insufficiency.

This results in venous pulsations in the umbilical vein and reversal

of the a-wave in the ductus venosus. Abnormal venous Doppler

studies are correlated with a significant risk of fetal acidaemia (OR

45 for umbilical vein pulsation) and intellectual impairment and

are the most compelling Doppler predictor of stillbirth.

The progression of fetal growth restriction follows a predict-

able physiological pattern and can be longitudinally assessed by

a multitude of surveillance tools such as CTG, ultrasound and

Doppler. This allows optimal timing of delivery, thereby

achieving the maximal gestational age without compromising

perinatal morbidity and mortality. Single tool assessment pro-

vides insufficient representation of fetal wellbeing.

It is reasonable to repeat umbilical artery Dopplers every 2

weeks if the indices are normal. If there is severe FGR or

abnormal umbilical artery Doppler surveillance should be more

frequent- twice weekly for raised indices and daily for absent or

reversed end diastolic flow. The ductus venosus should be used

to time delivery in those with abnormal umbilical artery Doppler

prior to 32 weeks gestation. A change in maternal condition (e.g.

development of pre-eclampsia or antepartum haemorrhage)

should also coincide with reassessment of the fetus.

Biophysical profile (BPP)

This method of assessment consists of an antenatal CTG, and

three ultrasound measurements of fetal behaviour assessed over

a 30 minute time period (fetal breathing, movements and tone),

in addition to measurement of the amniotic fluid. Each parameter

can be awarded a maximum score of two (when the parameter is

present, versus zero if it is absent; there is no intermediate score

Crown Copyright � 2014 Published by Elsevier Ltd. All rights reserved.

Practice points

C Assessment of fetal growth and wellbeing requires certainty of

gestational age e accuracy is strengthened by routine first

trimester ultrasound dating.

C Women with more than one major risk factor for SGA fetus should

have serial ultrasound measurements for growth and wellbeing

from 26 to 28 weeks onwards.

C Women with three or more minor risk factors should be offered

uterine artery Doppler assessment at 20e24 weeks and abnormal

values should result in serial ultrasound measurements for

growth and wellbeing. Normal values should have a single third

trimester assessment of fetal size and wellbeing.

C Reduction in fetal movements reported should prompt further

standardized assessments of fetal wellbeing.

C Customized growth charts may improve the sensitivity of SFH

measurement in identification of SGA fetuses.

C Consideration should be taken for use of ultrasound assessment

over SFH measurements in certain women.

C Umbilical artery Doppler has no role in assessment of low-risk

pregnancies.

C In high-risk fetuses the use of umbilical artery Doppler reduces

perinatal mortality, morbidity, antenatal admissions, induction of

labour and caesarean section.

C Serial measurement of multiple vessel Doppler studies in at-risk

pregnancies should be used when there is proven fetal compro-

mise. The strongest predictors of stillbirth are umbilical venous

pulsations and reversal of the a-wave in the ductus venosus.

REVIEW

of one), therefore giving a maximum score of 10. The abnor-

malities in a BPP are caused by fetal neuro-behavioural adapta-

tions in response to hypoxaemia, although the changes are not

specific for hypoxaemia and are associated with other factors

including certain medications and gestational age. Identifying

fetal compromise, at a score of 4 or less, has a sensitivity of

87.5% and specificity of 99.2%, compared to at a score of 8 or

less, which has a 29.2% sensitivity and 91.5% specificity,

respectively. One of the problems with this assessment method is

that it is time consuming, with a minimum ultrasound time of 30

minutes followed by 30 minutes on a CTG, and expensive. At-

tempts have therefore been made to shorten the test and a

modified BPP assessment (consisting of a CTG recording and

amniotic fluid measurement) was developed. Comparing per-

formance of the BPP to modified BPP assessment and to con-

ventional CTG monitoring a Cochrane review (underpowered)

found no significant difference between groups in perinatal

deaths, Apgar scores below 7 at 5 minutes, or overall caesarean

section rates. Currently insufficient evidence exists to support the

use of BPP as a test of fetal wellbeing in high-risk pregnancies

Uterine artery Doppler changes are apparent much earlier

than a reduction in BPP scores. Observational studies have

shown that global reduction in fetal movements and breathing

equate to a mean pH of between 7.10 and 7.20. The disease

process is even further advanced when there is additionally a

reduction in fetal tone. To reduce perinatal mortality, the BPP

would need daily reassessment to identify rapid deterioration in

the fetus. The high negative predictive value may suggest the

BPP is better suited for use in timing delivery when there is

proven abnormality on uterine artery Doppler.

Conclusion

Assessment of risk factors for abnormal fetal growth should take

place early in the first trimester to ensure appropriate levels of

monitoring and surveillance are instituted at appropriate times in

the pregnancy. Each pregnancy requires its own individual plan

with a possibility of increasing surveillance should the clinical

situation change. In high-risk pregnancies, Doppler is used both

as a predictor of fetal outcome, with uterine artery Doppler, and

as surveillance, with multiple fetal vessel Doppler measurements

to predict progressive deterioration in fetal pathology. Ultra-

sound is an important assessment tool for fetal growth and is

additionally beneficial in groups where accurate SFH assessment

of fetal growth is not possible. Computerized CTG may improve

perinatal mortality, in comparison to traditional CTG, however, it

is poor in long term prediction of fetal health. There are currently

no forms of antenatal fetal monitoring that can accurately predict

acute events like fetomaternal haemorrhage, cord accident or

placental abruption. A

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Crown Copyright � 2014 Published by Elsevier Ltd. All rights reserved.