There appears to be a different threshold of expression, which means that one gender is more likely to show the problem, over the other gender. For example, pyloric stenosis is four times more common in males than females. Once a child has been born with pyloric stenosis, the chance for it to happen again depends upon the gender of the child already born with the condition, as well as the gender of the next child. Babies 2 to 8 weeks old are at the highest risk. Caucasians seem to develop pyloric stenosis more frequently than babies of other races.
Boys develop pyloric stenosis four to five times more often than girls.
Because the stomach opening becomes blocked and babies start vomiting, several problems can happen. The most serious problem is dehydration. Babies have smaller bodies than adults and cannot tolerate losing fluid as easily as adults can. Minerals that the body needs to stay healthy, such as potassium and sodium, are also lost as the baby vomits. Babies who lack the right amount of water and minerals in their bodies can become very sick very quickly.