Aetiology and antenatal diagnosis of spina bifida
Spinal neural tube defects (NTDs) result from failure of neural tube closure that normally occurs at 15 - 28 days after conception. Birth prevalence figures for spina bifida vary, but on average are around 0.1%. There are no recent figures for South Africa, but previous studies have shown an incidence of 0.77 - 6.1/1 000 live births, with higher incidences in rural areas. The true incidence of NTDs is thought to be higher, but is difficult to calculate as this includes both spontaneous and therapeutic pregnancy losses.