ATLANTA (Reuters Health) – Women diagnosed with phenylketonuria (PKU) need to watch their protein intake during pregnancy to prevent newborn birth defects, according to a study conducted by the US Centers for Disease Control and Prevention (CDC).
"More than 90% of infants born to women with PKU who are not using medical foods and managing their diet have mental retardation," Dr. Amanda Brown of the CDC's National Center for Birth Defects and Developmental Disabilities told Reuters Health. "To have healthy babies, women with PKU need to be on the diet before they become pregnant and stay on it throughout pregnancy," she said.
A study published in the February 15th issue of the CDC's Morbidity and Mortality Weekly Report describes the pregnancy outcomes of three women with PKU. Two women with PKU were not adherent to a protein-restricted diet supplemented by medically prescribed amino acid-restricted supplements, while the third woman did adhere to dietary recommendations during pregnancy.
The first case was a 21-year-old woman who discontinued her PKU diet early in adolescence. She did not undergo any dietary supervision nor did she monitor her phenylalanine levels during pregnancy. Her infant was born with both microcephaly and developmental delay.
The second case was a 21-year-old woman with dietary noncompliance also dating back to adolescence. Despite a willingness to adhere to her diet during pregnancy, financial obstacles and lack of transportation prevented access to proper care and the nearest metabolic clinic. Her pregnancy resulted in a newborn with microcephaly.
The third case was a 27-year-old woman who had maintained her diet throughout adulthood and was consistent about monitoring phenylalanine levels. She had full access to a metabolic clinic during pregnancy and was able to cover the out-of-pocket cost of her diet-related treatment. She gave birth to a healthy infant.
Although this study dealt specifically with PKU during pregnancy, Dr. Brown emphasized the importance of maintaining the PKU diet before and after giving birth.
"When newborn screening and diet intervention began, it was thought that people with PKU could safely discontinue their diet after the brain matured," Dr. Brown explained. But it was later learned that some people with PKU who do not adhere to a restrictive diet develop other health problems, such as difficulties with memory, concentration, or behavior.
"So it is particularly important for women with PKU to plan their pregnancies, return to the diet, and stay on the diet for life," she said.