Most kids are fully toilet trained by age 5, but there's really no target date for developing complete bladder control. Between the ages of 5 and 7, bed-wetting remains a problem for some children. After 7 years of age, a small number of children still wet the bed.

No one knows for sure what causes bed-wetting, but various factors may play a role:

• A small bladder. Your child's bladder may not be developed enough to hold urine produced during the night.
• Inability to recognize a full bladder. If the nerves that control the bladder are slow to mature, a full bladder may not wake your child — especially if your child is a deep sleeper.
• A hormone imbalance. During childhood, some kids don't produce enough anti-diuretic hormone (ADH) to slow nighttime urine production.
• Urinary tract infection. This infection can make it difficult for your child to control urination. Signs and symptoms may include bed-wetting, daytime accidents, frequent urination, red or pink urine, and pain during urination.
• Sleep apnea. Sometimes bed-wetting is a sign of obstructive sleep apnea, a condition in which the child's breathing is interrupted during sleep — often due to inflamed or enlarged tonsils or adenoids. Other signs and symptoms may include snoring and daytime drowsiness.
• Diabetes. For a child who's usually dry at night, bed-wetting may be the first sign of diabetes. Other signs and symptoms may include passing large amounts of urine at once, increased thirst, fatigue and weight loss in spite of a good appetite.
• Chronic constipation. The same muscles are used to control urine and stool elimination. When constipation is long term, these muscles can become dysfunctional and contribute to bed-wetting at night.
• A structural problem in the urinary tract or nervous system. Rarely, bed-wetting is related to a defect in the child's neurological system or urinary system.

Bed-wetting can affect anyone, but it's twice as common in boys as in girls. Several factors have been associated with an increased risk of bed-wetting, including:

• Stress and anxiety. Stressful events — such as becoming a big brother or sister, starting a new school, or sleeping away from home — may trigger bed-wetting.
• Family history. If one or both of a child's parents wet the bed as children, their child has a significant chance of wetting the bed, too.
• Attention-deficit/hyperactivity disorder (ADHD). Bed-wetting is more common in children who have ADHD.

Although frustrating, bed-wetting without a physical cause doesn't pose any health risks. However, bed-wetting can create some issues for your child, including:

• Guilt and embarrassment, which can lead to low self-esteem
• Loss of opportunities for social activities, such as sleepovers and camp
• Rashes on the child's bottom and genital area — especially if your child sleeps in wet underwear