COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Prognosis Khalil A, Kalafat E, Benlioglu C, et al. SARS-CoV-2 infection in pregnancy: A systematic review and meta-analysis of clinical features and pregnancy outcomes. EClinicalMedicine. 2020 Aug;25:100446. doi: 10.1016/j.eclinm.2020.100446. Epub 2020 Jul 3.

Background: Perform a systematic review and meta-analysis of SARS-CoV-2 infection and pregnancy.

Methods: Databases (Medline, Embase,, Cochrane Library) were searched electronically on 6th April and updated regularly until 8th June 2020. Reports of pregnant women with reverse transcription PCR (RT-PCR) confirmed COVID-19 were included. Meta-analytical proportion summaries and meta-regression analyses for key clinical outcomes are provided.

Findings: 86 studies were included, 17 studies (2567 pregnancies) in the quantitative synthesis; other small case series and case reports were used to extract rarely-reported events and outcome. Most women (73.9%) were in the third trimester; 52.4% have delivered, half by caesarean section (48.3%). The proportion of Black, Asian or minority ethnic group membership (50.8%); obesity (38.2%), and chronic co-morbidities (32.5%) were high. The most commonly reported clinical symptoms were fever (63.3%), cough (71.4%) and dyspnoea (34.4%). The commonest laboratory abnormalities were raised CRP or procalcitonin (54.0%), lymphopenia (34.2%) and elevated transaminases (16.0%). Preterm birth before 37 weeks' gestation was common (21.8%), usually medically-indicated (18.4%). Maternal intensive care unit admission was required in 7.0%, with intubation in 3.4%. Maternal mortality was uncommon (~1%). Maternal intensive care admission was higher in cohorts with higher rates of co-morbidities (beta=0.007, p<0.05) and maternal age over 35 years (beta=0.007, p<0.01). Maternal mortality was higher in cohorts with higher rates of antiviral drug use (beta=0.03, p<0.001), likely due to residual confounding. Neonatal nasopharyngeal swab RT-PCR was positive in 1.4%.

Interpretation: The risk of iatrogenic preterm birth and caesarean delivery was increased. The available evidence is reassuring, suggesting that maternal morbidity is similar to that of women of reproductive age. Vertical transmission of the virus probably occurs, albeit in a small proportion of cases.

Funding: N/A.

Discipline / Specialty Area Score
Infectious Disease
Hospital Doctor/Hospitalists
Internal Medicine
Intensivist/Critical Care
Comments from MORE raters

Hospital Doctor/Hospitalists rater

Internal medicine physicians don't usually care for obstetric patients. It's probably more relevant to obstetricians and pediatricians than to internal medicine docs.

Hospital Doctor/Hospitalists rater

This provides useful context when counselling pregnant patients with COVID regarding its implications (or lack thereof).

Hospital Doctor/Hospitalists rater

I would like to have seen a better description of study characteristics as part of this paper. The quality assessment underestimates the risk for bias. Retrospective studies are at much higher risk for bias than stated in this paper. Nevertheless, this is important and useful information.

Intensivist/Critical Care rater

Nice review of the current literature, but not much new in the manuscript overall.

Obstetrics rater

SARS-2 is a new mutation that has attracted global attention among general public as well as medical community. This meta analysis of observational publications on SARS-2 is, so far, the most informative I have seen. The high rate of 3rd trimester infection is probably because this is a new infection. Other associations correlate well with the recent epidemiologic evidence on SARS-2 by CDC. I deduct morbidity and mortality is not higher among pregnant than non-pregnant young women. These results can be used for pregnant patient counseling.

Obstetrics rater

This systematic review and meta-analysis showed that maternal morbidity and mortality from SARS-CoV-2 infection are not significantly higher in pregnant women compared with non-pregnant women. Moreover, it also allayed the fear of possible vertical transmission. Hence, precautions of transmission of infection should be universal regardless of the pregnancy status.

Respirology/Pulmonology rater

This is important information for most of countries where maternal mortality is high, including the USA.