Brief Answer:
Can be chromosomal defect.

Detailed Answer:
Hello dear XXXX,

Thanks for your query.

I understand your concern.

FACTORS OFTEN ASSOCIATED WITH INTRAUTERINE GROWTH RESTRICTION:

FETAL: Chromosomal disorders (autosomal trisomies).
Namely trisomy 18 and to less extent trisomy 13.
So chromosomal anomalies can cause severe growth restriction.
There are procedures that can detect chromosomal anomalies but they are done around 10 -16 weeks of pregnancy not at this gestational age of 28 weeks.
Children less than 1000 grams are categorized in to extreme low birth weight.
Survival chances are 51% for infants with a birth weight of 500-749g, and 84.5% for infants with a birth weight of 750-1000g. These figures are at very good institutions with well-equipped and trained staff areas. Infants with extremely low birth weight (ELBW) are more susceptible to all of the possible complications of premature birth, both in the immediate neonatal period and after discharge from the nursery.
There are many long term effects:
1 Hypoxia, ischemia: Mental retardation, spastic diplegia, microcephaly, seizures, poor school performance
2 Intraventricular haemorrhages: Mental retardation, spasticity, seizures, hydrocephalus
3 Sensorineural injuries: Hearing, visual impairment, retinopathy of prematurity, strabismus, myopia
4 Respiratory failure Bronchopulmonary dysplasia, cor-pulmonale, bronchospasm, malnutrition, subglottic stenosis
5 Necrotizing enterocolitis Short-bowel syndrome, malabsorption, malnutrition, infectious diarrhoea
6 Cholestatic liver disease Cirrhosis, hepatic failure, malnutrition
7 Nutrient deficiencies: Osteopenia, fractures, anaemia, growth failure
8 Social stresses

These are only few to mention, there is long list to go.
These are not to scare you but potential side effects of low birth weight babies.
Hope i answered your query. If any question you can ask me in follow up query.
Or direct question at WWW.WWWW.WW Regards

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