Prevalence of single umbilical artery, clinical outcomes and its risk factors: A cross-sectional study

Background: Single umbilical artery (SUA) is found in 0.5–6% of all pregnancies worldwide. Although the association of SUA with some congenital malformations is mainly accepted, its effect on pregnancy/neonatal outcomes is still controversial.
Objective: This is the first study aimed to approximate the SUA prevalence in southern part of Iran. SUA epidemiologic features accompanied by some of its effects on pregnancy/neonatal outcomes are investigated as well.
Materials and Methods: In this cross-sectional study, data from two referral centers in Southern Iran were analyzed. In total, 1,469 pregnancies, fetuses, and neonates were examined for epidemiological features associated with SUA. SUA was confirmed by pathological examination, while congenital anomalies were diagnosed by clinical, ultrasound, and echocardiographical examinations. Data on pregnancy outcome were recorded based on the patients’ medical records.
Results: The prevalence of SUA was 3.47% (95% CI: 2.6–4.6%). Fetal anomalies including renal, cardiac, and other congenital anomalies, intrauterine fetal death, early neonatal death, low birth weight, low placental weight, and preterm birth were significantly higher in the SUA group (OR = 68.02, 31.04, 16.03, 3.85, 11.31, 3.22, 2.70, and 2.47, respectively). However, the maternal multiparity was lower in the SUA group (OR = 0.65; 95% CI: 0.44–0.98).
Conclusion: A significant association was observed between SUA and increased risk of intrauterine fetal death and early neonatal death, as well as low birth weight and preterm birth. Obstetrical history of the mother like parity was identified as an important predictor of SUA. Further investigations are suggested on risk stratification of neonates in this regard.

Keywords
Umbilical cord; Single umbilical artery; Pregnancy outcome; Congenital abnormalities.