Adjusted for maternal age, marital status, parity, residential city,
delivery type and infant sex.
In calculating the cumulative exposure dose to lockdown, we assigned a
weighting of 3 to days with Level I response, 2 to days with Level II
response, 1 to days with Level III response, and 0 to other days.
a: The exposed group refers to the pregnant women who have experienced
the COVID-19 lockdown in their first 22 GWs. The other participants were
defined as the unexposed group. The individual cumulative exposure dose
was calculated by combining the weightings with the overlap between
their pregnancy period ≤22 GWs and the three levels of responses. Q1-Q4
were defined as the cumulative exposure dose of the exposed group
classified by quartiles, and the unexposed group was used as reference.
b: Pregnant women who have experienced the COVID-19 lockdown (from
1/23/2020 to 2/24/2020) during any period of their pregnancy were
defined as the exposed group. We further divided the exposed group into
subgroups according to their gestational weeks (GW) on 1/23/2020, the
beginning of lockdown. -: Not applicable.
Table 3. Associations of
exposure to the COVID-19 lockdown with preterm birth