Inability to control excretion .
Starting and stopping urination relies on normal function in pelvic and abdominal muscles, diaphragm, and control nerves. Babies' nervous systems are too immature for urinary control. Later incontinence may reflect disorders (e.g., neural tube defect causing "neurogenic bladder"), paralysis of urinary system muscles, long-term bladder distension, or certain urogenital malformations. Weak pelvic muscles can allow small urine losses on coughing or sneezing ("stress incontinence"). Uncontrolled defecation can result from spinal or bodily injuries, old age, extreme fear, or severe diarrhea . See also enuresis .