Assessment of Fetal Growth & Development

1. Assessment of Fetal Growth & Development Module B – Part I

2. 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.

3. Antenatal Assessment • Antenatal = Prenatal • Includes • 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

4. 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

5. 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

6. 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

7. 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

8. 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.

9. Toxemia • Eclampsia – Occurrence of 1 or more convulsive seizures not attributed to other cerebral conditions, during pregnancy. • Occurs in 1 of 200 preeclamptic patients. • Coma. • Seen between 20 weeks and term. • May be fatal if untreated. • Can occur post-delivery.

10. 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.

11. Causes of Neonatal Asphyxia • Maternal hypoxia or asphyxia. • Decreased placental blood flow. • Anemia of the fetus. • Drugs taken by the mother or given to the mother.

12. Assessment of the Fetus • Ultrasonography • Amniocentesis • Fetal Biophysical Profile • Nonstress/Contraction Stress Testing • Fetal Heart Rate Monitoring • Fetal Blood Scalp Blood Analysis

13. Ultrasonography • Uses high frequency sound waves to locate and visualize organs and tissues. • Placental placement. • Amniotic fluid volume. • Assess fetal growth.

14. 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

15. L/S ratio PG (Phosphatidylglycerol) Alpha Fetoprotein (AFP) Sign of skin rupture Cytology of cells Creatinine Bilirubin Detection of meconium Fetal fecal matter Amniocentesis

16. Biophysical Tests of Fetal Well-Being • A prenatal “APGAR” score • Score of 0 (abnormal) or 2 (normal) on 5 variables: • 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

17. 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.

18. 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 • Maternal Fever/Infection • Infection of the fetus • Maternal dehydration • Maternal anxiety • Asphyxia • Drugs given to the mother

19. 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) • Most common. • Cord compression. • May indicate fetal hypoxia. • Usually doesn’t correlate with contractions

20. Early or Type I Decelerations

21. Late or Type II Decelerations

22. Variable or Type III Decelerations

23. 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.

24. 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

25. Estimated Date of Confinement (EDC) • Delivery Date • None of the methods are exact • Nägele’s Rule • Fundal Height • Quickening • Determination of Fetal Heartbeat

26. 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

27. 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.

28. 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.

29. 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).

30. 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).