Main Findings
This study comprehensively examined the associations of the COVID-19 lockdown with gestational length and risk of PTB using a large database from South China. We found that the lockdown exposure was significantly associated with a slightly shorter gestational length and a moderately higher risk of PTB. These associations were greater among women who were in early or middle pregnancy during the Level I lockdown period. There were also significant exposure-response associations of higher cumulative exposures to lockdown with a shorter gestational length and an increased risk of PTB.