Table 4. Difference-in-Differences Analysis of Racial/Ethnic Disparities in Preterm and Very Preterm Births Among Women Testing Negative for SARS-CoV-2.

Outcome	Before pandemic (March 28 to July 31, 2019)			Pandemic (March 28 to July 31, 2020)			Risk difference before vs during pandemic, % (95% CI)
	Denominator	Cases, No.	Risk, %	Denominator	Cases, No.	Risk, %
Black vs White births
Preterm birth
Non-Latina White	2188	156	7.1	1824	127	7.0	−0.2 (−1.8 to 1.4)
Non-Latina Black	451	65	14.4	445	59	13.3	−1.2 (−5.7 to 3.4)
Difference			7.3			6.3	−1.0 (−5.8 to 3.8)
Adjusted differencea,b							−0.9 (−5.8 to 4.0)
Very preterm birth		5124
Non-Latina White	2188	17	0.8	1824	10	0.6	−0.2 (−0.7 to 0.3)
Non-Latina Black	451	20	4.4	445	21	4.7	0.3 (−2.5 to 3.0)
Difference			3.7			4.2	0.5 (−2.3 to 3.3)
Adjusted differencea,b							0.7 (−2.2 to 3.6)
Latina vs White births
Preterm birth
Non-Latina White	2188	156	7.1	1824	127	7.0	−0.2 (−1.8 to 1.4)
Latina	688	74	10.8	600	61	10.2	−0.6 (−3.9 to 2.8)
Difference			3.6			3.2	−0.4 (−4.1 to 3.3)
Adjusted differencea,b							−0.6 (−4.4 to 3.1)
Very preterm birth
Non-Latina White	2188	17	0.8	1824	10	0.6	−0.2 (−0.7 to 0.3)
Latina	688	10	1.5	600	9	1.5	0.0 (−1.3 to 1.4)
Difference			0.7			0.9	0.3 (−1.1 to 1.7)
Adjusted differencea,b							0.3 (−1.2 to 1.7)

Abbreviation: SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

^aAdjusted for maternal age (continuous), parity (nulliparous, multiparous), prepregnancy body mass index (BMI; calculated as weight in kilograms divided by height in meters squared) (BMI <25, BMI ≥25), and insurance coverage (Medicaid, private, and other or self-pay); model for Black vs White very preterm birth disparity not adjusted for insurance coverage owing to nonconvergence.

^bObservations with missing covariate values dropped from adjusted analyses (<4% for BMI, <1% all others).