Study settings and subjects
We selected all hospitals in Foshan (n=62) and several other hospitals
in Guangzhou (n=1), Shenzhen (n=1), Dongguan (n=2), and Jiangmen (n=1)
in Guangdong Province, South China, as study settings (Figure 1 - Map).
All hospital birth data from
1/1/2015 to 12/31/2020 were collected (n=749059). Birth records with
multiple births (n=27659), stillbirths (n=726), or missing information
on key variables (n=2883) were excluded. Moreover, 122395 births were
excluded because their pregnancy did not overlap with the COVID-19
lockdown in 2020 or the same calendar months in 2015-2019. Finally,
595396 mother-newborn pairs were included. None of these women had a
positive SARS-CoV-2 test result (Figure S1 - Flowchart).