Table 4 Stillbirths to women admitted to hospital with symptomatic SARS-CoV-2 by dominant variant period and severity of maternal infection, March 1, 2020, to March 31, 2022, United Kingdom

From: Perinatal outcomes after admission with COVID-19 in pregnancy: a UK national cohort study

SARS-CoV-2 dominant variant

Wild-type period

Alpha period

Delta period

Omicron period

Severitya

Mild

(N = 1067)

Moderate to severea

(N = 370)

Mild

(N = 1220)

Moderate to severea

(N = 678)

Mild

(N = 1420)

Moderate to severea

(N = 1055)

Mild

(N = 1098)

Moderate to severea

(N = 208)

Stillbirths - no. (%)

9 (0.8)

6 (1.6)

12 (1.0)

9 (1.3)

42 (3.0)

20 (1.9)

8 (0.7)

5 (2.4)

Model 1b: RR

(95% CI)

[Ref]

1.93

(0.68–5.38)

1.17

(0.49–2.76)

1.57

(0.63–3.95)

3.49

(1.70–7.18)

2.25

(1.03–4.92)

0.86

(0.32–2.34)

2.86

(0.96–8.46)

Model 2c: RR

(95% CI)

[Ref]

1.90

(0.61–5.88)

1.20

(0.49–2.97)

1.68

(0.63–4.51)

3.57

(1.66–7.67)

2.41

(1.03–5.60)

0.96

(0.35–2.66)

2.62

(0.79–8.69)

Model 3d: RR

(95% CI)

NA

NA

[Ref]

0.99

(0.33–3.01)

2.82

(1.29–6.16)

1.89

(0.81–4.40)

0.79

(0.25–2.47)

2.07

(0.64–6.76)

  1. Abbreviations: GA gestational age, RR risk ratio, CI confidence interval, NA Not available.
  2. aModerate to severe COVID-19 defined as one or more of the following. maternal death, intensive care unit admission, peripheral oxygen saturation below 95% at admission, pneumonia on imaging, or need for respiratory support with oxygen, high flow nasal cannula or continuous positive pressure mask, mechanical ventilation or extracorporeal membrane oxygenation.
  3. bModel 1: Variant + severity + interaction term for variant and severity.
  4. cModel 2: Model 1  + maternal age, ethnicity, employment status, body mass index, multiple pregnancy, smoking, parity, pre-existing medical conditions, pre-eclampsia, gestational diabetes, and gestational age at admission.
  5. dModel 3: Model 2 + vaccination status. Vaccination started from January 1, 2021, therefore mild alpha infection was used as the reference group.
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