Types: Based on the clinical evaluation and ultrasound examination the small fetuses are divided into:
1. Fetuses that are small and healthy. The birth weight is less than 10 th percentile for their gestational age. They have normal ponderal index, normal subcutaneous fat and usually have uneventful neonatal course.
2. Fetuses where growth is restricted by pathological process (true IUGR). Depending upon the relative size of their head, abdomen and femur, the fetuses are subdivided into:
Etiology: The causes of fetal growth retardation can be divided into four types.
Maternal nutrition before and during pregnancy – Critical substrate requirement for the fetus such as glucose, aminoacids and oxygen are lacking during pregnancy.
This is an important cause of small weight of the babies in the developing countries.
As most of the fetal weight gain (two-third) occurs beyond 24 th week of pregnancy, malnutrition, anaemia, hypertension, antiphospholipid syndrome in the second half of pregnancy play significant role in the reduction of the birth weight.
The causes include cases of poor uterine blood flow to the placental site for a long time.
This leads to chronic placental insufficiency with inadequate substrate transfer.
This occurs in conditions such as preeclampsia, essential hypertension, chronic nephritis, organic heart disease, placental and cord abnormalities such as chronic placental abruption, infarction, small placenta, circumvallate placenta, vellamentous insertion of cord etc.
Measurement of the abdominal girth showing stationary or falling values.
Serial clinical examination by abdominal palpation to measure the relative growth of the uterus and its contents is the commonly used method. The diminishing amniotic fluid volume can also be assessed with fair degree of accuracy.
Physical features show dry and wrinkled skin because of less subcutaneous fat, scaphoid abdomen, thin meconium stained vernix caseosa and thin umbilical cord. All these give the baby an ‘old man look’. Pinna of ear has cartilaginous ridges. Plantar creases are well defined.
The baby is alert and having normal cry. Eyes are open.