- 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  .

·     Multiple pregnancies:

-        Impaired growth results from failure to provide optimal nutrition for >1 fetus in utero.

-        In total, 15% to 30% of multiple pregnancies develop FGR;

-        the condition is more common in monochorionic twins affected by twin-to-twin transfusion syndrome.

-        Up until the 28th to 30th week of pregnancy, fetuses in multiple pregnancies have growth rates similar to singletons; however, after this period, there is a 15% to 20% ↓ in the growth rate.

-        The degree of FGR ↑ with increasing number of fetuses.

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·  Maternal hypoxemia associated with cyanotic congenital heart disease, Chronic pulmonary disease, hemoglobinopathies, especially sickle cell disease, Infants born at high altitudes tend to have lower mean BW for gestational age.

·     Previous small for gestational age newborn.

·     Previous stillbirth (unless placental insufficiency was excluded).

·     Heavy first-trimester antepartum bleeding

·     Uterine malformations.

·     small maternal size (height and prepregnancy weight) and low maternal weight gain during pregnancy. Low maternal body mass index is a major predictor of IUGR.

·     Other maternal factors such as low socio-economic status, extreme maternal age, primiparity and grand multiparity.

·     Assisted reproductive technologies: Singleton pregnancies conceived via assisted reproductive technologies have a higher prevalence of small for gestational age infants compared with naturally conceived pregnancies.