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 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 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. 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 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 PG (Phosphatidylglycerol) Alpha Fetoprotein (AFP) Sign of skin rupture Cytology of cells Creatinine Bilirubin Detection of meconium Fetal fecal matter

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

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 Tachycardia 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

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

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 Nägele’s Rule Fundal Height Quickening Determination of Fetal Heartbeat

Nägele’s Rule Most common method used to determine EDC Example: 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).