Associations of COVID-19 lockdown exposure with PTB
A higher PTB rate (5.7% vs 5.3%) and MPTB rate (5.2% vs 4.9%) were observed in the exposed group compared to the unexposed group in the total sample. Significant increases in PTB risk (adjusted OR=1.08, 95%CI: 1.05, 1.11) and MPTB risk (adjusted OR=1.09, 95%CI: 1.05, 1.12) were also observed after adjusting for confounders (Table 3). However, the association between lockdown and VPTB was not statistically significant (adjusted OR=1.04, 95%CI: 0.94, 1.16). Subgroup analyses showed significant associations of lockdown exposure with increases in PTB and MPTB only among pregnant women <24 GWs on the first day of lockdown. The OR values varied between 1.10 and 1.20 for PTB and MPTB.
We also observed a positive association between cumulative exposure dose to lockdown and PTB risk (Table 3 and Table S3). Each 100 unit increase in the lockdown exposure during the first 22 GWs was significantly associated with 1.07 (95%CI: 1.05, 1.09), 1.07 (1.05, 1.08), and 1.12 (1.06, 1.18) times higher risks in PTB, MPTB, and VPTB, respectively. The adjusted ORs of PTB for the Q1, Q2, Q3 and Q4 quartiles of cumulative exposure (vs no exposure) were 1.16 (1.08, 1.23), 1.22 (1.14, 1.30), 1.14 (1.07, 1.22), and 1.19 (1.11, 1.27), respectively.