A distended upper abdomen, also known as diastasis recti, is typically caused by the stretching and resultant thinning of the linea alba tissues along the front wall of the stomach, according to Twiniversity. The linea alba tissues are connective tissues that join the intra-abdominal muscles together.
When these tissues are stretched or over-extended, a gap may form between them creating the distended abdomen. The thinning is typically the result of extreme pressure on these intra-abdominal muscles, which can be created by pregnancy, according to Twiniversity. A twin or triplet pregnancy, as well has having two or more children close in age or having a very heavy baby, makes this condition more likely. Likewise, having a pregnancy over the age of 35 presents a higher risk of diastasis recti, according to WebMD.
A distended upper abdomen can also be caused by yo-yo dieting or by using incorrect form while doing sit ups or weightlifting. Some abdominal exercises can aggravate the condition and increase the gap in the muscle wall, reports WebMD. These exercises include planks, sit ups, pull ups or push ups.
This condition typically heals on its own, though physical therapy, a stomach band or specific abdominal exercises may help, according to WebMD.