. 2021 Nov;10(11):3075–3081. doi: 10.21037/tp-21-494

Table 3. Comparison of serum 25-(OH)D level and vitamin D deficiency rate between the two groups.

Detection time	Relevant factors	BPD group (n=79)	Non-BPD group (n=207)	t/χ²	P value
At birth	25-(OH)D ( $\bar{x} \pm s$ , nmol/L)	33.7±15.1	49.5±19.6	t=3.435	<0.001
At birth	Vitamin D deficiency, n (%)	70 (88.7)	146 (70.5)	χ²=0.317	<0.001
6 months after 40 weeks of corrected gestational age	25-(OH)D ( $\bar{x} \pm s$ , nmol/L)	51.9±16.5	66.3±22.1	t=5.257	<0.001
6 months after 40 weeks of corrected gestational age	Vitamin D deficiency, n (%)	57 (72.1)	89 (43.0)	χ²=19.452	<0.001

P<0.05 was statistically significant. BPD, bronchopulmonary dysplasia.