Assessment of Fetal Growth &
Development
Module B – Part I
Objectives
• List three maternal-fetal risk factors.
• Differentiate between the various ways to
assess fetal growth, development, and
status.
• Differentiate between the various abnormal
heart rate patterns.
• Describe the significance of meconium in
the amniotic fluid.
Antenatal Assessment
• Antenatal = Prenatal
• Includes
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Maternal History
Evaluation of Maternal-Fetal Risk Factors
Physical Assessment
Intrapartum Monitoring
High Risk Conditions
• Maternal mortality: 6 of 100,000 births
• Perinatal mortality: 17 of 1,000 births
Maternal History & Risk Factors
• Preterm Birth
• Birth before 37 weeks is the greatest cause of neonatal
morbidity and mortality.
• 8% of births.
• Smaller the infant, greater the risk.
• Consequence of:
• Preterm labor
• Preterm rupture of membranes
• Fetal or maternal distress
• Prior preterm births
• 1 prior preterm birth: 15% risk of subsequent
• 2 prior preterm births: 32% risk
• Uterine Malformation and Incompetent Cervix
Maternal History & Risk Factors
• Toxic Habits in Pregnancy
• Present in 10% of pregnancies
• Smoking
• CO & Nicotine decrease fetal oxygen delivery.
• Correlation between cigarette smoking & low birth
weight.
• Associated with:
• Premature membrane rupture
• Placental disorders
• SIDS
• Alcohol Use
• Teratogenic
• Fetal Alcohol Syndrome
Maternal History & Risk Factors
• Toxic Habits in Pregnancy
• Illicit Drug Use
• Cocaine is a potent vasoconstrictor:
• Reduced maternal coronary blood flow.
• Reduced placental blood flow.
• Opiates and Amphetamine use are shown to result
in depressed neonatal function & withdrawal
symptoms.
• Poor Nutrition
• Presence of Diabetes
• Lack of Prenatal Care
Maternal History & Risk Factors
• Multiple Births
• Maternal Infection
• Group B Streptococcus
• Herpes Simplex Virus
• HIV & Hepatitis B
• Abnormalities of the Placenta, Umbilical Cord &
Fetal Membranes
• See Below
• Disorders of Amniotic Fluid Levels
• Mode of Delivery
• See Below
• Toxemia
Toxemia
• Complicates 6 to 8% of deliveries
• 2nd only to pulmonary embolism as cause of
maternal death.
• Preeclampsia –
• A blood pressure greater than 140/90 mm Hg.
• A rise in blood pressure greater than 30 mm Hg
systolic or 15 mm Hg diastolic during pregnancy.
• Proteinuria
• Edema of face & hands
• Pressures over 150/100 mm Hg is considered
severe preeclampsia.
• If not treated can lead to Eclampsia.
Toxemia
• Eclampsia – Occurrence of 1 or more
convulsive seizures not attributed to other
cerebral conditions, during pregnancy.
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Occurs in 1 of 200 preeclamptic patients.
Coma.
Seen between 20 weeks and term.
May be fatal if untreated.
Can occur post-delivery.
NEONATAL ASPHYXIA
• Combination of hypoxia, hypercapnia and
acidosis leads to neonatal asphyxia.
• Asphyxia leads to irreversible damage to
the brain and vital organs.
• Asphyxia can occur in utero or during the
delivery.
• GOAL SHOULD BE TO IDENTIFY AND
PREVENT ASPHYXIA.
Causes of Neonatal Asphyxia
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Maternal hypoxia or asphyxia.
Decreased placental blood flow.
Anemia of the fetus.
Drugs taken by the mother or given to the
mother.
Assessment of the Fetus
• Ultrasonography
• Amniocentesis
• Fetal Biophysical Profile
• Nonstress/Contraction Stress Testing
• Fetal Heart Rate Monitoring
• Fetal Blood Scalp Blood Analysis
Ultrasonography
• Uses high frequency sound waves to locate
and visualize organs and tissues.
• Placental placement.
• Amniotic fluid volume.
• Assess fetal growth.
Amniocentesis
• Amniocentesis is obtaining a sample of
amniotic fluid for testing purposes
• 3.5 - 4 inch 20 – 22 gauge needle
• Guided by ultrasound
• Can be performed at 15 weeks but more
commonly during the 2nd & 3rd trimester
• Complications are infection, trauma and
hemorrhage
Amniocentesis
•L/S ratio
•Creatinine
•PG (Phosphatidylglycerol) •Bilirubin
•Alpha Fetoprotein (AFP) •Detection of meconium
•Sign of skin rupture
•Cytology of cells
•Fetal fecal matter
Biophysical Tests
of Fetal Well-Being
• A prenatal “APGAR” score
• Score of 0 (abnormal) or 2 (normal) on 5
variables:
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Fetal Breathing (1 breath in 30 seconds) - U
Fetal Movement (3 movements in 30 minutes) - U
Fetal Limb Tone (1 extension/flexion in 30 minutes) - U
Reactive Fetal Heart Rate (2 reactive episodes
[acceleration of FHR >15 bpm] in 20 minutes) - NST
• Amniotic Fluid Volume (One 1x1 cm pocket) - U
• Normal Score is 8-10
• 10 is normal; 0 to 4 abnormal.
• TABLE 3-1 p. 26
Fetal Heart Rate Monitoring
• Average fetal HR is 140/min (120 to 160/min)
• Decreases to 120/min near term.
• Fetal Heart Rate Monitoring can determine fetal
distress.
• Fetal Heart Rate Monitoring is correlated with
uterine contractions during labor.
Fetal Heart Patterns
• Baseline Heart Rate
• Bradycardia
• Less than 120 beats/minute or a drop of 20 beats/minute or more from
baseline heart rate.
• Common causes:
• Asphyxia (rule out immediately)
• Give the mother oxygen may help.
• Fetal scalp sample for pH determination.
• Congenital Heart Defects
• Hypothermia
• Drugs/medications given to mother
• Tachycardia
• HR above 160/min
• Causes
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Maternal Fever/Infection
Infection of the fetus
Maternal dehydration
Maternal anxiety
Asphyxia
Drugs given to the mother
Fetal Heart Patterns
• Decelerations: HR drops below 120/min for less
than 2 minutes.
• Early Decelerations (Type I)
• Usually due to fetal head compression.
• Poses little threat to fetus.
• Late Decelerations (Type II)
• Uteroplacental insufficiency.
• Begin at peak of contractions.
• Associated with fetal distress.
• Variable Decelerations (Type III)
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Most common.
Cord compression.
May indicate fetal hypoxia.
Usually doesn’t correlate with contractions
Early or Type I Decelerations
Late or Type II Decelerations
Variable or Type III Decelerations
Fetal Scalp pH Assessment
• Asphyxia results in a drop of pH
• Increase in PaCO2
• Anaerobic metabolism resulting in increased
lactic acid.
• Procedure
• Mother is placed in a lithotomy position.
• Fetal head is visualized through the cervix.
• An incision is made in the scalp and a blood
sample is obtained.
Fetal Blood pH
• Normal fetal blood pH is above 7.25
• pH between 7.15 – 7.24
• Slight asphyxia
• pH less than 7.15
• Severe asphyxia
• The pH of the mother should be
determined concurrently
Estimated Date of Confinement
(EDC)
• Delivery Date
• None of the methods are exact
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Nägele’s Rule
Fundal Height
Quickening
Determination of Fetal Heartbeat
Nägele’s Rule
• Most common method used to determine
EDC
• Subtract 3 months from the first day of the last
menstrual period.
• Add 7 days
• Example:
First day of last menstrual period is 3/25
Subtract 3 months = 12/25
Add 7 days = January 1
Fundal Height
• The Fundus of the uterus is the end
opposite the cervix and can be
measured as the uterus grows with the
fetus
• Unreliable during the last trimester
• A measurement is taken from the
symphysis pubis to the top of the fundus
• If the distance is 20 cm, the gestation is 20
weeks.
Quickening
• Quickening is the first sensation of fetal
movement experienced by the mother.
• 16 – 22 weeks (average is 20 weeks).
• Very rough estimation of fetal age.
Determination of Fetal Heartbeat
• Fetal heartbeat can be heard as early as 16
weeks.
• Nearly always heard by 20 weeks.
• With the use of Doppler devices, the
heartbeat can be heard earlier (8 weeks).
Meconium Presence in Amniotic
Fluid
• Meconium is the thick, dark greenish stool
found in the fetal intestine.
• Passage of the meconium into the
amniotic fluid occurs in 40% of post-term
fetuses of greater than 42 weeks
gestation.
• This occurs due to asphyxia.
• Meconium release may result in
meconium aspiration syndrome (MAS).