What is hypospadias?

Hypospadias is a birth defect in boys in which the urethra, the tube that urine travels through from the bladder to outside the body, doesn't develop properly. The urethra begins as an open channel that gradually closes as the child develops. In babies born with hypospadias, the opening of the urethra forms in another location — on the shaft of the penis or on the scrotum — instead of on the tip, where it is supposed to be.

Other features seen in boys with hypospadias include:

  • The penis curves downward (chordee).
  • In about 10% of the cases of hypospadias, one of the testicles does not fully move down into the scrotum.
  • The foreskin (the skin that covers the head of the penis) is incompletely developed.

Hypospadias is a common problem, affecting one of every 250 to 300 newborn boys. If it is not treated, hypospadias can lead to problems later in life, such as having to sit down to urinate or difficulties with sexual intercourse.

What causes hypospadias?

The specific causes of hypospadias are unknown. However, there is a family trend: fathers and brothers of children with hypospadias are slightly more likely to have the abnormality.

Male and female genitalia are similar during the first eight or so weeks of development in the womb. The penis begins to develop after the eighth week. The defect in the urethra occurs between weeks nine and 12 of pregnancy.

Certain factors in the mother may lead to an increased risk of hypospadias, including:

  • Obesity
  • Over age 35
  • Use of fertility treatment to help with conception. This may be a result of the mother's exposure to progesterone, a hormone used during the fertilization procedure
  • Use of other hormones before or during pregnancy (pesticide exposure)
  • Smoking

Pregnant women can reduce the risk of hypospadias and other birth defects by practicing healthy behaviors, including:

  • Not smoking or drinking alcohol
  • Staying at a healthy weight
  • Taking 400 to 800 micrograms (mcg) of folic acid a day
  • Seeing the doctor regularly while pregnant

The rate of hypospadias appears to be rising in Western cultures. One theory for this increase is the use of environmental pollutants, especially hormone-like compounds that are used in pesticides on fruits and vegetables.