There are many factors which affect the integrity of the abdominal wall. Pregnancy is certainly the most obvious cause of diastasis and abdominal wall laxity, but weight fluctuations can have an effect, as well. Age, per se, is not as significant a cause, but many people gain weight with age. In women, the deposition of fat changes as hormone levels change with age, and many women find that fat settles more in their midsection over time. Because of this, you may have a sense that your abdomen is more relaxed and/or fuller than it was when you were younger. Abdominal wall laxity can be corrected surgically, but intra-abdominal fat is something that only diet and exercise can fix. Visit a board certified Plastic Surgeon for an evaluation and they should be able to give you advice on your options.