Maternal and fetal wellbeing Flashcards
What is the difference between gravidity and parity?
Gravidity is the total number of pregnancies, regardless of outcome
Parity is the total number of pregnancies carried over the threshold of viability (24 weeks)
What is FGR/IUGR?
Fetal Growth Restriction (FGR) or Intrauterine Growth Restriction (IUGR)
Occurs when a fetus is unable to achieve its genetically determined potential size.
What are fetal causes of FGR/IUGR?
Chromosomal disorders - trisomies 13 and 18
Malformations
Congenital infections such as rubella, HIV
Multifetal pregnancy
What are maternal causes of FGR/IUGR?
Smoking (active or passive)
Alcohol (cross placental barrier)
Drugs e.g cocaine (causes vasoconstriction and affects maternal circulation)
Chronic morbidities such as hypertension, diabetes, heart disease, obesity
Severe anaemia
Low pregnancy weight
What are placental causes of FGR/IUGR?
Abnormal placental implantation
Placental infarcts (interrupted blood supply to a part of placenta)
Single umbilical artery (an umbilical abnormality)
Placenta abruption (separation of placenta from the walls of the uterus - partial or completely)
What is the average weight of boys and girls when born? What is classed as large weight/small weight?
Average weight Girls 3.2 kg (7Ib 2oz) (50th centile) Boys 3.3 kg (7Ib 6oz) (50th centile) Large weight Over 4.5 kg (9Ib 14oz) Small weight Under 2.5 kg (5Ib .5oz)
What are the different categories of prematurity?
Extremely preterm (less than 28 weeks) Very preterm (28 to 32 weeks) Moderate to late preterm (32 to 37 weeks)
What are the risks of prematurity? (e.g. hypothermia - little fat, babies unable to shiver, homeostasis)
Hypoglycaemia/Hypocalcaemia Respiratory distress syndrome - fetus produces surfactant around 24-28 weeks Neonatal jaundice Necrotising enteritis Brain haemorrhage Inc risk of cerebral palsy
What can we do if there is a risk of prematurity?
Steroids (Betamethasome)
Stimulates synthesis of surfactant and Prevent brain haemorrhage
Magnesium Sulphate as a neuroprotectant
reduce the risk of cerebral palsy
What type of tests can determine fetal growth and wellbeing?
Fetal growth - Biometric
Fetal wellbeing - Biophysical
What are the Biometric parameters?
1st trimester: Crown rump length 2nd trimester onwards: Biparietal diameter (BPD) Head circumference (HC) Abdominal Circumference (AC) Femur Length (FL)
What 5 assessments make up the biophysical profiling?
Amniotic fluid volume Fetal breathing movements Fetal tone Gross body movements Reactive fetal heart rate
What makes up the amniotic fluid? What does it contain?
Firstly, it consists of water from the maternal body
Later (20/40 weeks) it is made up of the fetus’s urine, as the fetus swallows and excretes fluid
Nutrients
Hormones
Antibodies
Fetal urine
What are the functions of the amniotic fluid?
Protecting the fetus Temperature control Infection control Lung and digestive system development Muscle and bone development Lubrication Umbilical cord support
What are Oligohydramnios and Polyhydramnios?
Oligohydramnios – too little amniotic fluid
Polyhydramnios – too much amniotic fluid
How is amniotic fluid vol regulated?
By swallowing
Movement of fluid in GI may enhance growth and development of GI tract
What might we see if there is a GI abnormality?
Polyhydramnios is also known as hydramnios
Abnormality that blocks the passage of fluid
Abnormal swallowing due to problems in CNS
Chromosomal abnormality
Too much amniotic fluid can cause the uterus to become overdistended and lead to premature labour
Describe the fetal urinary system.
Urine enters bladder empties every 40-60mins into amniotic fluid
At 25 weeks fetus produces about 100ml urine per day
Rising to about 500 ml at term
Fetus swallows amniotic fluid constantly
Absorbs water and electrolytes
What forms the meconium?
Debris from urine swallowing accumulates in fetal gut (this debris forms meconium)
How do we monitor the fetal urinary system?
Fetal kidney number / size /structure
Amniotic fluid volume
Bladder activity
What cardiac defects form the tetralogy of fallot?
- Pulmonary stenosis
- RV Hypertrophy
- Over-riding aorta
- VSD
How does the fetus carry out respiration, nutrition and excretion?
Relies on placenta
What cardiac fetal structures help with Feto-Placental Circulation?
Ductus arteriosus
Ductus venosus
Foramen ovale
Where does Oxygenated blood from placenta go after it arrives at the fetus in the umbilical vein?
50% of this blood enters a hepatic micro-circulation and later joins the IVC through the hepatic veins
Remaining blood passes directly to IVC through the ductus venosus (DV)
In addition to well –oxygenated blood from the placenta the IVC receives less-oxygenated blood from the abdomen, pelvis and lower limbs.
What does the foramen ovale do?
FO - one way valve that only permits blood flow from right to left
Flow patterns in the R atrium allow 50% of oxygenated blood from the placenta to be shunted to the L atrium
How is right to left flow through the FO maintained?
by the larger quantity & greater speed of blood flow from the IVC on the right compared with that entering the L atrium via the pulmonary veins from the lungs.
What structures allow blood to bypass the lungs?
Shunting of blood on the venous side by the FO and on the arterial side by the DA are structural devices that enable the blood to bypass the lungs & be directed to the placenta.
What is special about the umbilical veins?
Valveless
How do we monitor the fetal CVS during pregnancy?
Cardiotocography CTG
Baseline and acceleration and fetal movements
What are doppler flow studies?
(doppler velocimetry) are used to assess fetal health and reserve by assessing blood flow characteristics within the umbilical cord.
What circulatory adaptations occur after birth? (e.g. onset of breathing)
Onset of breathing, pulmonary vascular resistance decreases
Inc blood flow to the lungs -> inc vol of pulmonary venous blood returning to the left atrium
Left atrial pressure > right atrial pressure
Foramen ovale closes
ductus arteriosus (DA) begins to constrict:
full term infant - DA functionally closes within 1 day postnatally
permanent closure - several weeks
Ductus venosus remains partially open but closes within two-three months after birth.
