The first study of successful pregnancies in Chinese patients with Phenylketonuria

Since the inception of newborn screening programs in China in the 1990s, pregnancy among patients with inherited, metabolic disorders has become more common. This study explores the management and outcomes of planned, full-term pregnancies in patients with phenylketonuria (PKU).

Married patients with PKU from 2012 to 2017 were enrolled to receive prenatal counseling and regular health assessments. Study-related assessments included the timing of Phe-restricted diets, maternal weight gain, gestational age, pregnancy complications, and blood Phe concentrations (both pre-conception and during pregnancy), obstetrical data, and offspring outcomes(e.g. anthropomorphic measurements and developmental quotients [DQs]).

A total of six offspring were successfully delivered. The mean ± SD (range) age of the mother at delivery was 26.3 ± 4.7 (range: 21.1-32.5) years. The mean duration of Phe control before pregnancy was 5.5 ± 1.3(range: 3.1-6.5) months. During pregnancy, the proportion of blood Phe concentrations within the clinically-recommended target range (120-360 μmol/L) ranged from 63.2-83.5%. Low birth weight (< 2500 g) offspring occurred in two women who experienced suboptimal metabolic control. In addition, offspring DQ was related to the proportion of blood Phe levels per trimester that were within the recommended range (r = 0.886, p = 0.016).

This is the first report of women in China with PKU who successfully gave birth to clinically healthy babies. Infant outcomes were related to maternal blood Phe management prior to and during pregnancy. In maternal PKU patients with poor compliance to dietary treatment, sapropterin dihydrochloride (6R-BH₄) may be an option to improve the management of blood Phe levels.