Table 2.

Comparison of pre-COVID era (2017–2019) vs. COVID era (2020) low birth weight rates across five medical centers stratified by birth weight.

Center	Birth weight, g	Year	n	Rate	Rate Ratio (95% CI)	p value
All centers (excluding St Mary's Medical center)a (2017–19 N = 33,504; 2020 N = 9,377)	≤1,500	2017–19	476	1.4% (1.3, 1.6)	0.98 (0.81, 1.19)	0.832
		2020	136	1.5% (1.2, 1.7)
	>1,000 and ≤1,500	2017–19	297	0.9% (0.8, 1.0)	1.15 (0.89, 1.49)	0.274
		2020	72	0.8% (0.6, 1.0)
	≤1,000	2017–19	179	0.7% (0.5, 0.9)	0.78 (0.59, 1.04)	0.093
		2020	64	0.5% (0.5, 0.6)
Santa Clara Valley Medical Center San Jose, California (2017–19 N = 8,926; 2020 N = 2,780)	≤1,500	2017–19	92	1.0% (0.8, 1.3)	0.73 (0.51, 1.07)	0.107
		2020	39	1.4% (1.0, 1.9)
	>1,000 and ≤1,500	2017–19	56	0.6% (0.5, 0.8)	1.03 (0.60, 1.77)	0.926
		2020	17	0.6% (0.4, 1.0)
	≤1,000	2017–19	36	0.4% (0.3, 0.6)	0.51 (0.30, 0.87)	0.013
		2020	22	0.8% (0.5, 1.2)
O'Connor Hospital San Jose, California (2017–19 N = 4,085; 2020 N = 950)	≤1,500	2017–19	14	0.3% (0.2, 0.6)	1.09 (0.31, 3.78)	0.898
		2020	3	0.3% (0.1, 1.0)
	>1,000 and ≤1,500	2017–19	10	0.2% (0.1, 0.5)	1.16 (0.25, 5.31)	0.846
		2020	2	0.2% (0.1, 0.8)
	≤1,000	2017–19	4	0.1% (0.0, 0.3)	0.93 (0.10, 8.32)	0.948
		2020	1	0.1% (0.0, 0.7)
Cabell Huntington Hospital Huntington, West Virginia (2017–19 N = 7,849; 2020 N = 2,604)	≤1,500	2017–19	240	3.1% (2.7, 3.5)	1.21 (0.92, 1.58)	0.177
		2020	66	2.5% (2.0, 3.2)
	>1,000 and ≤1,500	2017–19	150	1.9% (1.6, 2.2)	1.38 (0.96, 1.99)	0.081
		2020	36	1.4% (1.0, 1.9)
	≤1,000	2017–19	90	1.1% (0.9, 1.4)	1.00 (0.66, 1.50)	0.982
		2020	30	1.2% (0.8, 1.6)
St Francis Medical Center Los Angeles, California (2017–19 N = 12,644; 2020 N = 3,043)	≤1,500	2017–19	130	1.0% (0.9, 1.2)	1.12 (0.74, 1.68)	0.594
		2020	28	0.9% (0.6, 1.3)
	>1,000 and ≤1,500	2017–19	81	0.6% (0.3, 0.9)	1.15 (0.68, 1.93)	0.608
		2020	17	0.6% (0.3, 0.9)
	≤1,000	2017–19	49	0.4% (0.3, 0.5)	1.07 (0.56, 2.06)	0.835
		2020	11	0.4% (0.2, 0.7)

^a St Mary's Medical Center data did not provide birth weight-based data thus was not included combined estimates.