Urinary 8-hydroxy-2′-deoxyguanosine levels and small-for-gestational age infants: a prospective cohort study from the Japan Environment and Children's Study

Objectives To evaluate the association between the urinary 8-hydroxy-2 '-deoxyguanosine (U8-OHdG) levels and the incidence of small-for-gestational age (SGA) infants and to assess the utility of U8-OHdG as a biomarker to predict the incidence of SGA infants. Design Prospective cohort study. Setting The Japan Environment and Children's Study. Participants Data of participants enrolled in the Japan Environment and Children's Study, a nationwide birth cohort study, between 2011 and 2014 were analysed; 104 062 fetal records were analysed. Data of women with singleton pregnancies >= 22 weeks of gestation were analysed. Primary and secondary outcome measures U8-OHdG levels were assessed using liquid chromatography-tandem mass spectrometry. Participants were categorised into the following three groups according to the quartile of the distribution of U8-OHdG: low U8-OHdG (<1.95 ng/mgCre), moderate U8-OHdG (the combined second and third quartiles; 1.95-2.95 ng/mgCre) and high U8-OHdG (>2.95 ng/mgCre) groups. Additionally, participants in the 90th percentile for U8-OHdG levels were analysed. Odds ratios (ORs) for SGA infants (<-1.5 and <-2.0 SD) were calculated using a logistic regression model while adjusting for confounding factors; the moderate U8-OHdG group was used as a reference. The cut-off value of U8-OHdG to predict the incidence of SGA infants was calculated using a receiver operating characteristic (ROC) curve analysis. Results Data of 80 212 participants were analysed. The adjusted ORs for SGA infants (<-1.5 and<-2.0 SD) in the high U8-OHdG group were 1.16 (95% CI 1.07 to 1.25) and 1.22 (95% CI 1.07 to 1.38). The cut-off value of U8-OHdG (3.26 ng/mgCre) showed a poor ability to predict SGA infants (sensitivity, 21.9%; specificity, 83.6%; area under the ROC curve, 0.530). Conclusions Elevated U8-OHdG levels were associated with an increased incidence of SGA infants. However, this parameter would not be a useful screening tool for predicting SGA infants owing to its low sensitivity and specificity.