Patterns of Intrauterine Growth Restriction.

 Patterns of Intrauterine Growth Restriction.

1.  Symmetric or non-symmetric:

	Symmetric	Non-symmetric
Onset	Early	Late
Incidence	less common ≈ 30% of FGR cases	more common ≈ 70%–80% of cases
Pattern of retardation	Symmetric, Infants have reductions in all organ systems with the body, head, and length proportionally affected.	Asymmetric, Infants have disproportionate growth restriction in which head circumference is preserved, length is somewhat affected but may be spared, and weight is compromised to a greater degree. The weight deficit is principally due to a reduction in fat deposition, particularly during the 3rd trimester of pregnancy. The disproportion is due to the redistribution of blood flow during fetal development with preferential perfusion of the brain, heart and adrenal glands at the expense of the kidney, GIT and liver, limbs and SC tissues.
	Reduction in cell number.	Reduction of cell size.
Head size	Decreased	Normal
Ponderal index	Normal	Decreased
Catch up growth	Less	More
Genetic growth potential	Not attainable	Attainable
Amniotic fluid	typically accompanied by normal amniotic fluid volume but may be accompanied by polyhydramnios if there is reduced fetal swallowing of amniotic fluid, e.g. trisomy 21 or GIT anomalies.	often oligohydramnios, which is a result of chronic stress on the fetus and reduced urine production.
Causes	usually is caused by intrinsic factors such as congenital   infections or chromosomal abnormalities, maternal drug and alcohol abuse or a chronic medical condition or malnutrition.	usually is caused by Extrinsic factors such as   disorders of the placenta or from maternal problems e.g uteroplacental dysfunction secondary to maternal pre-eclampsia, multiple pregnancy, maternal smoking or may be idiopathic.
Prognosis	poor prognosis, these infants are more likely to remain small permanently, decreased nutrient supply early in development can restrict growth of all organs.	good prognosis, these infants rapidly put on weight after birth.

- Placental factors Causing IUGR.

 Placental factors Causing Intrauterine Growth
Restriction

· Placental insufficiency due to maternal disorders, such as pre-eclampsia and eclampsia, or due to post-term gestation.

Ü Presence of asymmetrically grown fetus, low amniotic fluid index, and umbilical artery abnormalities (abnormal waveforms, absent or reversed end-diastolic flows) together suggests placental insufficiency.

·     Gross cord and placental abnormalities:

–       Single umbilical artery.

–       Abnormal umbilical vascular insertions (marginal cord insertion, circumvallate, velamentous).

–       bilobed placenta

–       circumvallate placenta.

–       multiple infarcts

–       umbilical vascular thrombosis and hemangiomas.

–       Infectious villitis (as with TORCH infections)

·     Placental mesenchymal dysplasia is a rare placental abnormality characterized by placentomegaly and grape-like vesicles resembling a partial mole. The euploid fetus with these findings is at increased risk for FGR, perinatal death, and Beckwith-Wiedemann syndrome.

·     Multiple gestations may be associated with significant placental problems such as abnormal vascular anastomoses and inability of the uteroplacental environment to meet the nutritional needs of multiple fetuses.

·     Abruption (chronic, partial).

·     Placenta previa

- Maternal factors causing IUGR.

  Maternal factors causing Intrauterine Growth
Restriction

·     Maternal genetic factors:

-        Mothers who were growth-restricted at birth have a twofold increase in risk for FGR in their offspring.

-        Mothers who give birth to an FGR newborn are at high risk of recurrence, and the risk increases with increasing numbers of FGR births.

·     Maternal disorders reducing uteroplacental blood flow: such as preeclampsia, eclampsia, chronic renal vascular disease, and chronic hypertensive vascular disease, Autoimmune syndromes (antiphospholipid, lupus erythematosus), and pregestational diabetes often result in ↓ uteroplacental blood flow and result in FGR, Impaired delivery of oxygen and other essential nutrients is thought to limit organ growth and musculoskeletal maturation. Risk of placental thrombi is increased in conditions of inherited thrombophilia.

·     Extreme and prolonged Maternal malnutrition:

-      because changes in maternal nutrition, unless extreme and prolonged, do not markedly alter maternal plasma concentrations of nutrient substrates or the rate of uterine blood flow, the principal determinants of nutrient substrate delivery and transport to the fetus by the placenta.

-      Zinc deficiency in pregnant women has been associated with increased rates of preterm delivery and fetal IUGR.

-      Thiamine deficiency in pregnant women also has been associated with IUGR.

-      Protein restriction rather than caloric restriction before 26 weeks can cause symmetric IUGR.

-      GIT diseases: Crohn’s, ulcerative colitis, gastrointestinal bypass surgery  .

- Maternal substance use causing IUGR.

 Maternal substance use causing Intrauterine Growth
Restriction