Small for Gestational Age (SGA)
What is SGA?
Small for Gestational Age (SGA) is the medical term for a child who is ‘too small’ at birth for his/her gestational age. About 5% of children are born with a low birth weight and/or short birth length for their gestational age. The medical term for this is “dysmaturity” with regard to growth.
What causes SGA?
The small birth weight/length can be caused by a problem affecting the child, the placenta or the mother.
- chromosome abnormalities
- twins, triplets, etc.
- foetal infections
- growth retardation syndromes in the uterus
- lack of certain hormones and growth factors (insulin, IGF-1, etc.)
- poor implantation in the uterus
- placental detachment
- vascular connections in multiple pregnancies
- small mother – small pelvis
- chronic diseases (anaemia, rheumatic diseases, heart diseases, etc.)
- pregnancy hypertension (preeclampsia, eclampsia)
- smoking, alcohol abuse, narcotics
How is SGA diagnosed?
During pregnancy: The baby’s size can be guessed by measuring the height from the top of a mother’s uterus to the pubic bone. This measurement corresponds with the number of weeks of pregnancy. If this measurement is low for the number of weeks pregnancy, then the baby may be smaller than average.
Ultrasound measurement of the femur length of the foetus is more precise.
After birth, this can be checked by plotting the birth length and weight on the growth curve (see short stature).
What are the signs and symptoms of SGA?
The newborn is comparatively small: low weight, short in length and small head size.
It has been found that a small birth length/birth weight increases the risk of many disorders many years later (sometimes 50-60 years later), such as diabetes, cardiovascular disease, high cholesterol, etc. Before and immediately after birth, the body “adapts” to the living conditions, referred to as ‘early life programming’. If there is, for example, little nutrition available at that moment, the body will be programmed not to become too big.
A long-term effect of dysmaturity can be permanent short stature. Almost all children make up for this growth delay at birth during the first 4 years of life, usually in the first 12 months. This does not happen in 5-10% of the children, and they remain small even as adults.
How is SGA treated?
If no catch-up growth has taken place at the age of four and the height is still below the -2.5 SD line (bottom of the lower grey zone on the Flemish growth curve), then a child may be eligible for growth hormone treatment.
The GH dose in this indication is higher than for GH deficiency. After all, these patients produce a normal amount of GH themselves. So in order to obtain an effect, the “natural” amount must be exceeded.
If treatment is started at least two years before the onset of puberty, an average height gain of 9-11 cm can be obtained as an adult. The treatment duration is then 6-8 years, as treatment is continued until the growth rate is less than 2 cm per year, or until the skeletal age is more than 14 years in girls and more than 16 years in boys.