Small for gestational age (SGA) has a high risk of mortality and morbidity and is common in obstetrics. To date, no effective prediction and treatment tools are available. Acting as microRNA (miRNA) sponges and disease biomarkers are clear functions of circular RNAs (circRNAs). However, it is still unknown what role circRNAs act in SGA. To explore the role of circRNAs in SGA, circRNA expression patterns of the umbilical cord and maternal plasma in SGA was assessed. We first evaluated circRNAs in umbilical cord blood of the SGA and appropriate for gestational age (AGA) groups by microarray sequencing. In total, 170 340 circRNAs were sequenced, and 144 circRNAs were significantly upregulated while 977 were markedly downregulated. Has_circRNA15994-13, has_circ_0001359, and has_circ_0001360 were abundant and differentially expressed between the SGA and AGA groups, and confirmed in the umbilical cord and maternal blood specimens by reverse transcription polymerase chain reaction. By combining miRNA microarray data of the SGA placenta tissue in NCBI, it was found that two miRNAs were both hsa_circRNA15994-13 targets and differentially expressed, including hsa-miR-3619-5p and hsa-miR-4741. Further KEEG analysis revealed that the most significant pathway enriched by hsa-miR-3619-5p was Wnt signaling that is closely related to SGA; meanwhile, previous reports demonstrated that hsa-miR-3619-5p directly binds to beta-catenin to accommodate the Wnt/beta-catenin pathway, whereby the suggestive hsa_circRNA15994-13 -> hsa-miR-3619-5p -> beta-catenin signaling pathway may play an important part in SGA.