Coronavirus (1417) Differences in pregnancy and perinatal outcomes among symptomatic versus asymptomatic COVID-19-infected pregnant women: a systematic review and meta-analysis

21 December, 2021

Dear HIFA colleagues,

(with thanks to Maternal Health Task Force)

CITATION: Differences in pregnancy and perinatal outcomes among symptomatic versus asymptomatic COVID-19-infected pregnant women: a systematic review and meta-analysis

Durray Shahwar A. Khan et al.

BMC Pregnancy Childbirth. 2021; 21: 801.

Published online 2021 Dec 1. doi: 10.1186/s12884-021-04250-1


Background: There is dearth of information on COVID-19’s impact on pregnant women. However, literature reported trends of COVID-19 differ, depending on the presence of clinical features upon presentation.

Objective: This systematic review aimed to assess differences in risk factors, management, complications, and pregnancy and perinatal outcomes in symptomatic vs. asymptomatic pregnant women with confirmed SARS-CoV-2 infection.

Methods: A search was run on electronic databases to identify studies reporting COVID-19 in pregnancy. Meta-analysis was performed and odds ratios and mean difference with 95% confidence intervals were calculated using Review Manager 5.4. Review Prospero registration number CRD42020204662.

Results: We included ten articles reporting data from 3158 pregnancies; with 1900 symptomatic and 1258 asymptomatic pregnant women. There was no significant difference in the mean age, gestational age, and body mass index between the two groups. The meta-analysis suggested that pregnant women who were obese (OR:1.37;95%CI:1.15 to 1.62), hypertensive (OR:2.07;95%CI:1.38 to 3.10) or had a respiratory disorder (OR:1.64;95%CI:1.25 to 2.16), were more likely to be symptomatic when infected with SARS-CoV-2. Pregnant women with Black (OR:1.48;95%CI:1.19 to 1.85) or Asian (OR:1.64;95%CI:1.23 to 2.18) ethnicity were more likely to be symptomatic while those with White ethnicity (OR:0.63;95%CI:0.52 to 0.76) were more likely to be asymptomatic. Cesarean-section delivery (OR:1.40;95%CI:1.17 to 1.67) was more likely amongst symptomatic pregnant women. The mean birthweight(g) (MD:240.51;95%CI:188.42 to 293.51), was significantly lower, while the odds of low birthweight (OR:1.85;95%CI:1.06 to 3.24) and preterm birth (< 37 weeks) (OR:2.10;95%CI:1.04 to 4.23) was higher amongst symptomatic pregnant women. Symptomatic pregnant women had a greater requirement for maternal ICU admission (OR:13.25;95%CI:5.60 to 31.34) and mechanical ventilation (OR:15.56;95%CI:2.96 to 81.70) while their neonates had a higher likelihood for Neonatal Intensive Care Unit admission (OR:1.96;95%CI:1.59 to 2.43). The management strategies in the included studies were poorly discussed, hence could not be analyzed.

Conclusion: The evidence suggests that the presence of risk factors (co-morbidities and ethnicity) increased the likelihood of pregnant women being symptomatic. Higher odds of complications were also observed amongst symptomatic pregnant women. However, more adequately conducted studies with adjusted analysis and parallel comparison groups are required to reach conclusive findings.


A wide spectrum of disease severity exists amongst pregnant women with COVID-19 disease, with 86% exhibiting mild disease, 9.3% severe, and 4.7% critical [27]. This percentage is similar to those calculated from the non-pregnant adult population (with 80% mild, 15% severe, and 5% critical disease) [28]. However, information regarding the reason for progression to critical disease, depending on the basis of clinical features of COVID-19, is still lacking in the literature.


Neil Pakenham-Walsh, HIFA Coordinator,