What causes Congenital pyloric stenosis?

Answer 1

Pyloric stenosis (PS) is "multifactorial" - there are many different factors that increase a baby's risk of developing it. These include heredity, gender, position in the birth order, race, blood group, maternal stress, breast feeding, various bio-chemical issues, the intake of a common antibiotic, etc.

Quite a list, but these are not the causes, which are still not well understood despite PS having been recognised and treated for more than a century!

Heredity is one of the most obvious and easily noted risk factors: twins from a single egg usually both have PS, unidentical twins rarely. Females are 4-6 times less likely to have PS, but when they've had it, it's stronger in their genes, so that the child of a mother who had PS will have an up to 20% chance of passing it on, whilst a father with a PS history brings a 5% risk of his child having it.

The incidence is quite variable: different studies have shown that in developed Western countries PS sometimes occurs in less than one baby in 1000, ranging to nearly 9 in every 1000. However often it occurs, it's fairly common and all of us know people who have had it. Babies at the greatest risk of PS are firstborn Jewish or Caucasian males with blood types B or O, and whose mother had it. The risk is increased slightly if the baby was born full term, belongs to a higher socio-economic group, or had a younger mother or one who was stressed during the last months of her pregnancy. Breastfeeding has been linked both positively and negatively, as have several other factors. The antibiotic erythromycin has been found to increase the danger of PS.

These notes indicate that PS incidence and genetic factors are easier to list than the actual causes, although the biochemistry of the development of the gut is worth studying for those who have enough background to understand the science.

The Wikipedia page on pyloric stenosis has a lot of useful information to add to this answer.