Fetal Growth And Assessment And Monitoiring

Question 1

Definitions fo growth statuses for fetuses

Answer 1

IUGR = fetuses <10th percentile

Small for gestational age (SGA) = newborns <10th percentile

Large for gestational age (LGA) = newborns > 90th percentile

Macrosomia = fetus is > 4000grams if diabetic and 4500 grams if not diabetic

Question 2

Pathophysiology of IUGR

Answer 2

Placenta abnormalities

• villous trophoblasts invade the decidua where the maternal vascular muscleelastic media decreases (doesn’t dilate like its suppose to)
• this causes fetal side vessels to not growth properly since the resistance is higher than its suppose to be

Fetal vessels only grow in low resistance and high capacitance

Any maternal cause of poor blood vessels compliance or chronic HTN can increase the risks as well as chromosomal abnormalities in fetus

• *aspirin mass play a role in IUGR but it is unknown**
• some benefit though

High S/D ratio is bad

Question 3

LGA and macrosomia pathophysiology

Answer 3

#1 = maternal diabetes being present 
- high glucose levels in maternal blood crosses into the fetus and causes hyperinsulinemia in the fetus. This causes the excess glucose to be converted into fat and causes the baby to growth larger 

** maternal birthweight is correlated directly but paternal birthweight is NOT correlated at all**

Question 4

Screening for fetal size

Answer 4

4 components (2 risk factor and 2 growth measurements)

1) risk factors for macrosomia
- diabetes
- pre-pregnancy obesity
- excessive gestational weight gain
- dyslipidemia
- history of macrosomia newborn in past
- posterm pregnancy

2) risk factors for growth restriction
- maternal medical condtions
- maternal substance use
- teratogenic exposure
- infectious diseases
- genetic or structural disorders
- placenta and umbilical cord disorders
- multiple gestation

3) fundal height measurement
- needs to be done after 24 weeks gestation
- measure from pubic symphysis to top of uterus fundus.
- weeks gestation = cm of fundal height +/- 3cm

4) ultrasound fetal biometry measurement
- femur length
- head circumference
- Abdominal circumference
- biparietal diameter
* * error of measurement is 8% (because of this need to do ultrasounds 3 weeks apart if abnormal and 4 weeks if normal)**

Question 5

Management of IUGR

Answer 5

Risks of continuing gestation = fetal demise, neonatal death and severe neonatal health complications

induction at an earlier gestational age is recommended

If isolated IUGR = delivery at 38 + 0 -> 39 +6

If additional issues are also present on top of IUGR (oligohydramnios, abnormal umbilical artery doppler, comorbidities, etc) = delivery at 32 + 0 -> 37 +6

Question 6

Management of macrosomia

Answer 6

Risks associated with vaginal delivery = shoulder dystocia, neonatal morbidity

** induction at earlier gestation ages ar not beneficial**

the C-section or vaginal delivery for a macrosomia baby still have equal risks for brachial plexus injuries

Delivery recommendations
- C-section if > 5000 in non diabetic mother and > 4500 in diabetic mother

Question 7

If abnormal weight for gestation what else do you monitor on top of ultrasound?

Answer 7

Weekly biophysical profile, umbilical artery Doppler, amniotic fluid index and 2x weekly NSTs (only 3rd trimester)