Untreated phenylketonuria (PKU) in pregnancy causes a severe embryopathy called maternal PKU syndrome. Here, we aimed to assess management issues and pregnancy outcomes in the first published series of PKU pregnancies from the developing world. Data were collected retrospectively in a single center from 71 pregnancies and 45 live births of 32 women with PKU, 11 of whom were diagnosed in adulthood after having an affected child. Microcephaly, intellectual disability, and dysmorphic facies were more prevalent in offspring of untreated than treated pregnancies with classical PKU (100% vs. 0%, 91% vs. 0%, and 73% vs. 23% with p<0.001, p<0.001, and p=0.037, respectively). In treated pregnancies, phenylalanine levels were higher during weeks 6-14 than other periods of gestation (4.38 vs. 3.93, 2.00 and 2.28mg/dl; p<0.05). Poor compliance correlated with higher phenylalanine levels (=-0.64, p=0.019) and fluctuations (=-0.66, p=0.014).Conclusion: More frequent phenylalanine measurements during late first trimester are crucial to improve outcomes in treated pregnancies. In order to prevent untreated pregnancies via detecting undiagnosed adults, countries where significantly many women of childbearing age were not screened as newborns may consider pre-pregnancy PKU screening. Microcephaly in the newborn should prompt screening for PKU in the mother.