Is there an intrauterine growth retardation in Bulgarian patients with phenylketonuria and hyperphenylalaninemia?

Background: There has been conflicting reports in the literature on reduced birthweight and intrauterine growth retardation (IUGR) in patients with phenylketonuria (PKU). The aim was to assess whether prenatal growth is affected in Bulgarian patients with PKU and hyperphenylalaninemia(HPA) and whether there are any gender differences.

Methods: All children were born at term. The birthweight and length of 61 patients (30 girls and 31 boys) with PKU and HPA, born in Bulgaria between 2004 and 2022, were compared with reference values using the Fenton growth chart. Height and weight were measured at birth by different nursing operators. Based on the weight the neonates were classified as small for gestational age (SGA < 10th percentile), appropriate (AGA 10–90th percentile) or large (LGA > 90th percentile).

Results: Mean weight was 3146 g at birth with mean weight for girls 3142 g and for boys 3249 g. Based on the birthweight we found 9 SGA (15% of children), 49 AGA (80%) and 3 LGA (5%). For the SGA group 5 were female (17% of all girls) and 4 were male (13% of all boys). For birth length the split was 3 children with length 90 percentile (8%). Surprisingly we found that 4 females had birth length above 90percentile (13% of all girls) but only one male (3% of all boys).

Conclusions: This is the first systemic review on IUGR in Bulgarian patients with PKU and HPA. We found that birthweight is more severely affected compared to the length for the Bulgarian population. Our results are consistent with the literature data for IUGR in PKU and HPA newborns.