TABLE 3.

Risk of preterm birth in 2020, with lockdown periods in March–May and October–December, compared with the same periods in 2016–2019, stratified by severity and type of preterm birth

Preterm birth	2016–2019 n preterm (%)	2020 n preterm (%)	OR (95% CI)	AOR (95% CI)a
Overall 22–36 wk
Jan–Feb	107 (4.4)	28 (4.0)	0.90 (0.59–1.39)	0.87 (0.56–1.35)
Mar–May	221 (5.6)	43 (4.1)	0.72 (0.51–1.00)	0.69 (0.49–0.97)
Jun–Sep	303 (5.2)	58 (3.6)	0.69 (0.52–0.92)	0.67 (0.49–0.89)
Oct–Dec	180 (4.5)	58 (5.6)	1.22 (0.90–1.66)	1.22 (0.89–1.67)
Severe 22–31 wk
Jan–Feb	14 (0.6)	6 (0.9)	1.49 (0.57–3.89)	1.35 (0.50–3.63)
Mar–May	27 (0.7)	9 (0.9)	1.25 (0.58–2.69)	1.15 (0.53–2.48)
Jun–Sep	58 (1.0)	11 (0.7)	0.69 (0.36–1.32)	0.61 (0.31–1.18)
Oct–Dec	26 (0.7)	10 (1.0)	1.49 (0.72–3.10)	1.45 (0.69–3.08)
Moderate 32–36 wk
Jan–Feb	93 (3.8)	22 (3.1)	0.81 (0.51–1.31)	0.79 (0.49–1.29)
Mar–May	194 (4.9)	34 (3.2)	0.64 (0.44–0.94)	0.63 (0.43–0.92)
Jun–Sep	245 (4.2)	47 (2.9)	0.69 (0.51–0.95)	0.69 (0.50–0.95)
Oct–Dec	159 (4.0)	48 (4.6)	1.17 (0.84–1.63)	1.18 (0.84–1.66)
Spontaneous 22–36 wk
Jan–Feb	45 (2.8)	17 (3.6)	1.28 (0.72–2.26)	1.18 (0.66–2.12)
Mar–May	105 (4.1)	24 (3.4)	0.83 (0.53–1.31)	0.75 (0.48–1.19)
Jun–Sep	149 (3.8)	22 (2.2)	0.57 (0.36–0.89)	0.52 (0.33–0.83)
Oct–Dec	88 (3.4)	26 (3.9)	1.14 (0.73–1.79)	1.19 (0.75–1.88)
Medically indicated 22–36 wk
Jan–Feb	62 (7.3)	11 (4.8)	0.64 (0.33–1.25)	0.63 (0.32–1.24)
Mar–May	116 (8.5)	19 (5.5)	0.63 (0.38–1.04)	0.61 (0.36–1.02)
Jun–Sep	154 (8.1)	35 (6.1)	0.74 (0.50–1.08)	0.75 (0.50–1.11)
Oct–Dec	97 (6.8)	31 (8.6)	1.28 (0.84–1.96)	1.21 (0.79–1.88)

Abbreviations: aOR, adjusted odds ratio; OR, odds ratio.

^a Adjusted for parity, maternal age, country of origin, residential area, cohabitation, employment, essential hypertension, and pre‐existing diabetes mellitus.