Table 1 Meta-analysis of maternal and perinatal outcomes in studies comparing COVID-19 vaccinated and unvaccinated pregnancies.

Outcome	Studies (n)	Vaccinated (n)	Unvaccinated (n)	Effect estimate^a	P	I² (%)
Vaccine effectiveness	3^22,23,24	18,828	18,828	89.5% (69.0 – 96.4%)	<0.0001	73.9
HDP	3^31,32,34	1765	6411	1.09 (0.84 – 1.41)	0.499	0.0
Pre-eclampsia	3^19,24,32	7756	9454	0.94 (0.53 – 1·66)	0.826	0.0
Placental abruption	3^8,31,34	1758	4948	0.57 (0.32–1.11)	0.105	0.0
Pulmonary embolism	2^24,32	7670	9392	0.34 (0.0–78.2)	0.698	NA
Postpartum haemorrhage	4^8,31,32,34	1898	6810	0.89 (0.5–1.44)	0.634	20.4
ICU admission	4^8,30,31,32	2317	12,084	1.45 (0.66–3.16)	0.356	0.0
Maternal death	6^{8,22,23,24,30,32}	20,403	29,819	0.32 (0.0–103.4)	0.696	NA

All P values are two-sided without any adjustments. Effects estimates were pooled using one of the following estimators (maximum-likelihood, restricted maximum-likelihood, inverse variance).
HDP hypertensive disorders of pregnancy, ICU intensive care unit admission, n number.
^aEffect estimates are reported as odds ratio (binary outcomes) and vaccine effectiveness (1-hazard ratio) and 95% confidence intervals.

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