Small for gestational age (SGA) refers to a fetus that is smaller in size than what is expected for the gestational age, as determined by ultrasound measurements of biometric parameters such as head circumference, abdominal circumference, and femur length. A fetus is considered SGA if it falls below the 10th percentile for gestational age. There are several causes of SGA, including: Maternal factors, such as malnutrition, chronic medical conditions, substance abuse, and smoking. Placental factors, such as poor placentation, placental insufficiency, or placental abruption. Genetic conditions such as chromosomal abnormalities or genetic syndromes Intrauterine infections, which can cause inflammation and damage to the placenta SGA can have serious consequences for the fetus, including an increased risk of stillbirth, neonatal death, and long-term developmental problems. It can also lead to a higher risk of complications during labor and delivery, such as a difficult delivery, and a higher risk of requiring a cesarean delivery. It's important to note that SGA should be evaluated in the context of gestational age, and should be compared to the expected growth for that gestational age. Additionally, after delivery, SGA newborns are also at a higher risk for metabolic and cardiovascular diseases later in life. Management of SGA fetuses may include close monitoring of fetal well-being, and interventions such as induction of labor or cesarean delivery if there is evidence of fetal distress.

1. Small
for gestational age

2. How to evaluate fetal weight ?
Low risk patients should undergo fundal height after 20 weeks
Moderate & High risk patients should have ultrasound evaluation of fetal weight
Ultrasound evaluation is done by measuring abdominal circumference or estimated fetal
weight that needs to measure (AC, HC , BPD, FL )
After evaluating fetal weight its plotted on a chart , if the weight fallen under the 10th centile its
SGA (small for gestational age )

4. SGA vs IUGR
SGA is a general term used to describe any fetus whose weight is under the 10th centile
IUGR is SGA but due to genetic or environmental factor as uteroplacental insufficiency
SGA and IUGR defined as estimated fetal weight under 10th centile
Sever IUGR is under 3rd centile

5. Pathophysiology and types of IUGR (FGR)

6. Symmetric or asymmetric
Symmetric :
means that the baby is mall in all his parts ( head circumference and abdominal circumference are both
small
HC:AC ratio is normal as they both decreases
Occur in early insults , chromosomal , infections (CMV , Patau , Edward , ….etc)
Asymmetric
Means that the abdominal circumference is lower
AC:HC is low
Occur in late insults , placental cause
as in mothers with vascular diseases , HTN , renal diseases ,PET

8. Symmetrical : associated with factors that directly impair fetal growth such as chromosomal disorders and
fetal infections
Asymmetrical : is classically associated with uteroplacental insufficiency that leads to reduced oxygen
transfer to the fetus and impaired excretion of carbon dioxide by the placenta leading to fetal brain vasodilatation
(brain sparing )
Sparing of vital organs (fetal brain, myocardium and adrenal glands)
Vasoconstriction of less important organs (kidneys, splanchnic vessels, limbs and subcutaneous tissues,
liver)leading to decrease abdominal circumference
Reduced renal blood flow will lead to decrease urine output and oligohydramnios
Fetal Stress increasing corticosteroid , catecholamine and erythropoietin level (polycythemia )
Reduced thyroxin , insulin , amino acid and glucose
Chronic nutritional deficiency leads to fetal acidemia (both metabolic and respiratory )

9. Causes of IUGR

10. Fetal causes
Most of cases are SGA with no pathological cause and good outcome
Pathological fetal cause are less common cause than other causes
Aneuploidies, e.g. trisomy 18
Single gene defects (e.g. Seckel’s syndrome)
Structural abnormalities (e.g. renal agenesis)
Intrauterine infections (e.g. cytomegalovirus, toxoplasmosis)

11. Maternal causes
Undernutrition (e.g. poverty, eating disorders)
Maternal hypoxia (e.g. living at altitude, cyanotic heart disease)
Drugs (e.g. alcohol, cigarettes, cocaine)

12. Placental causes
Most common pathological cause of IUGR (most common overall in SGA is constitutional )
Reduced uteroplacental perfusion (e.g. inadequate trophoblast invasion, sickle cell disease,
multiple gestation)
Reduced fetoplacental perfusion (e.g. single umbilical artery,
twin-to-twin transfusion syndrome)

13. Managing the pregnancy
Risk assessment for IUGR is essential in all pregnancies
Done by history , examination , investigation

14. History
Taking a proper history is essential to identify people at risk and divide them to low risk ,
moderate risk and high risk
Low risk ….. Fundal hight
Moderate risk … uterine artery doppler at 20-24 weeks
High risk …. Serial fetal weight assessment by ultrasound and doppler from 26-28 weeks

16. Examination
All low risk people should have SFH (fundal height )and if low to be seen by ultrasound to
evaluate fetal weight and amniotic fluid
If the patient is high risk , direct serial ultrasound fetal growth from 26 weeks is needed
The most precise way of assessing fetal growth is by ultrasound biometry
(biparietal diameter, head circumference, abdominal circumference and femur length) serially
at set time intervals (usually of 4 weeks and no less than 2 weeks)

17. Prevention
Low-dose aspirin may have a role in the prevention of FGR in high risk pregnancies but is not
effective in the treatment of established cases
Avoidance of some modifiable risk factors as alcohol and smoking reduces the risk

18. Evaluation of SGA case
After diagnosing SGA, next step is to look for the cause, to see if its constitutional after ruling
out all pathological causes
Look for the cause?
Doppler study of the umbilical artery , middle cerebral artery , ductus venosus
Detailed ultrasound for congenital anomalies
Work up for TORCH if history is suggestive
Amniotic fluid assessment

19. Treatment
The definitive treatment is TIMED DELIVERY before insult occur
Details of the treatment is most probably out of the scope of internship exam

20. Complications of IUGR
●Premature delivery
●Perinatal asphyxia, which may be accompanied by meconium aspiration or persistent pulmonary
hypertension
●Impaired thermoregulation
●Hypoglycemia
●Polycythemia and hyper viscosity
●Impaired immune function
●Mortality
As adult , the fetus will be at more risk to develop metabolic disorders as diabetes , hypertension
and cardiovascular diseases