Vitamin D Status of Preterm Newborns at Approximately 4 Weeks of Age in Shenzhen, China: A Retrospective Observational Cohort Study Conducted Across Two Centers

Yanping Guo,1 Zhangbin Yu,2 Huiying Tu,2 Biying Zheng,1 Jiamin Li,1 Ying Liu1 1Department of Pediatrics, Peking University Shenzhen Hospital, Shenzhen, Guangdong, People’s Republic of China; 2Department of Neonatology, Shenzhen People’s Hospital (The Second Clinical Medical College, Jinan University, the First Affiliated Hospital, Southern University of Science and Technology), Shenzhen, Guangdong, People’s Republic of ChinaCorrespondence: Yanping Guo; Ying Liu, Tel +86-15919990131 ; +86-13902992158, Email guoyanping1223@163.com; 13902992158@139.comBackground and Objectives: To examine the correlation between the concentration of vitamin D (VD) in venous blood at approximately 4 weeks of age (± 4 weeks of age) and neonatal outcomes in preterm infants (birth weight < 1500 g or gestational age < 32 weeks) in two neonatal intensive care units (NICUs) located in Shenzhen, China.Methods and Study Design: Preterm infants were split into two groups based on their VD concentration at ± 4 weeks of age: VD insufficiency (VDI) group (≤ 20 ng/mL) and VD sufficient (VDS) group (> 20 ng/mL). Binary logistic regression analysis was used to examine relationships between outcomes and VDI.Results: Of 230 infants in total, 119 (51.7%) were assigned to the VDI group and 111 to the VDS group (48.3%). No correlation was found between serum VD at ± 4 weeks of age and gestational age (p> 0.05). The starting point of the two groups for oral VD intake did not differ significantly (p> 0.05). At ± 4 weeks of age, oral VD dose (P< 0.05) was greater in the VDS group. Gestational diabetes mellitus was associated with VDI (OR=1.94, 95% CI 1.01– 3.75, p=0.047) after controlling for this risk. Following correction for gestational age and oral VD dosage at ± 4 weeks old, VDI was also linked to a significant risk of retinopathy of prematurity (OR=2.00, 95% CI 1.08– 3.68, p< 0.027).Conclusion: Preterm newborns (gestational age < 32 weeks or birth age < 1500 g) in NICUs in Shenzhen, China continue to have significantly high VDI. Higher VDI is associated with gestational diabetes mellitus and retinopathy of prematurity.Keywords: very preterm birth, very low birth weight infant, vitamin D, 4 weeks of age, outcome