Pregnancy and PKU

Women who have PKU and become pregnant are at risk of another form of the condition called maternal PKU. If women don't follow the special PKU diet before and during pregnancy, blood phenylalanine levels can become high and harm the developing fetus or cause a miscarriage.

Even women with less severe forms of PKU may place their unborn children at risk by not following the PKU diet.

Babies born to mothers with high phenylalanine levels don't often inherit PKU. But they can have serious consequences if the level of phenylalanine is high in the mother's blood during pregnancy. Complications at birth may include:

• Low birth weight
• Delayed development
• Facial abnormalities
• Abnormally small head
• Heart defects and other heart problems
• Intellectual disability
• Behavioral problems

When to see a doctor

Seek medical advice in these situations:

• Newborns: If routine newborn screening tests show that your baby may have PKU, your child doctor will want to start dietary treatment right away to prevent long-term problems.

  

  Newborn screening

  
  
• Women of childbearing years: It's especially important for women with a history of PKU  to see a doctor and maintain the PKU diet before becoming pregnant and during pregnancy to reduce the risk of high blood phenylalanine levels harming their unborn babies.
• Adults: People with PKU continue to receive care across the life span. Adults with PKU who have stopped the PKU diet in their teens may benefit from a visit with their doctors. Returning to the diet may improve mental functioning and behavior and slow damage to the central nervous system that can result from high phenylalanine levels.