What causes a newborn to get pyloric stenosis?

No one knows ...: For sure. Given that hypertrophic pyloric stenosis (hps) occurs 5 times more commonly in boys than girls, and 5 times more commonly in whites than blacks (1 out of every 300 newborn white baby boys), there most be some genetic basis to causation. However, there may be some environmental input into causation also.

Who knows: There are several theories but no one really knows. We know how to recognize and treat it, but cannot prevent it even if there is a family history.

Not always known: Pyloric stenosis can have either an environmental or a genetic cause, and when occurring together these two will raise the likelihood of occurring.Pyloric stenosis is four times more common in males. Some families have aggregate of cases in certain familiies. It's about four times more likely to occur in firstborn male infants