Author; Study country; Year of Publication [Reference number]	Type of study	Sample size	Main findings	Conclusion
Al-Matary et al.; Saudi Arabia; 2021 [13]	Cohort study	288	・ A majority of pregnant women were symptomatic with cough being the most frequent COVID-19 symptom. ・ Caesarean section made up 35.8% of the deliveries. ・ Prematurity (15.5%) was the most common adverse pregnancy outcome, followed by foetal distress (6.5%) and pre-eclampsia (2.0%). ・ Less than half (43%) of neonates of COVID-19 positive mothers were admitted into the neonatal intensive care unit (NICU) for respiratory support. ・ None of the newborns were positive for COVID-19 infection.	・ The majority of the pregnant women with COVID-19 infection experienced mild or moderate disease symptoms. ・ No evidence was found to suggest vertical transmission of COVID-19 infection from mothers to their newborns.
Ayed et al.; Kuwait; 2020 [14]	Cohort study	185	・ The majority of the pregnant women experienced mild symptoms of COVID-19, with fever (58.6%) being the most common presenting symptom. ・ 1.6% of the pregnant women had a miscarriage and 8.6% had ongoing pregnancies, while 89% had a live birth. ・ The median gestational age at birth for newborns was 38 (IQR: 36 - 39) weeks. ・ Only 2 newborns were tested positive for COVID-19 on day 5 by nasopharyngeal swab testing.	・ Most pregnant women infected with COVID-19 had mild symptoms. ・ While there is a possibility of mother-to-child vertical transmission when a pregnant woman is infected with COVID-19, it may not lead to unfavourable maternal and neonatal outcomes.
Crovetto et al.; Spain; 2021 [15]	Cohort study	317	・ A majority of the COVID-19 positive pregnant women were asymptomatic (68.5%) or had mild symptoms (29.3%). ・ Symptomatic women had higher rates of preterm delivery (16.9% vs 7.2%; P = 0.03) and intrapartum foetal distress (19.2% vs 9.1%, P = 0.004) when compared to non-infected women, however, the rates for asymptomatic women were similar to those of non-infected cases. ・ None of the newborns of COVID-19 positive mothers had anti-SARS-CoV-2 IgM/IgA in cord blood.	・ In general, there was little difference in the rates of pregnancy complications between infected and non-infected women. ・ An increase in preterm delivery and intrapartum foetal distress was associated with symptomatic COVID-19 infection.
Cruz-Melguizo et al.; Spain; 2021 [16]	Cohort study	1347	・ There were higher rates of premature rupture of membranes, venous thrombotic events and severe pre-eclampsia incidence in COVID-19 positive pregnancies compared to non-infected pregnancies, which could have been overestimated in the infected cohort due to the shared clinical signs of the hypertensive disorders and COVID-19. ・ More infected patients delivered preterm mainly due to a higher rate of iatrogenic preterm births. ・ Prematurity in COVID-19 affected pregnancies results from a predisposition to terminate the pregnancy due to maternal disease.	・ Pregnant women with COVID-19 are at risk of preterm deliveries, mainly due to iatrogenic deliveries secondary to pneumonia and/or pre-eclampsia. ・ A higher proportion of infected women reported venous thromboembolism and disseminated intravascular coagulation.
Haye et al.; Chile, 2021 [17]	Cohort study	458	・ A majority (74.4%) of the COVID-19 positive women presented with mild symptoms and 25.5% of them experienced severe COVID-19 symptoms. ・ 5.6% women were admitted into the ICU and 2.8% of them required mechanical ventilation. ・ Adverse maternal outcomes were linked to severe COVID-19 presentation, infection over 24 weeks, and comorbidities. ・ 16.5% of the deliveries were preterm.	・ Maternal compromise resulted from women with severe COVID-19 and the occurrence of disease in the second half of the pregnancy. ・ The high perinatal morbidity and mortality in severe COVID-19 positive women warrants attention. ・ Outpatient management was safe for mild cases.
Khoury et al.; USA; 2020 [18]	Cohort study	241	・ A majority of women were asymptomatic for COVID-19 at the time of admission. ・ 52.4% of women with severe and 91.7% with critical COVID-19 underwent caesarean delivery. ・ The rate of preterm delivery was 14.6%. ・ Body mass index (BMI) of 30 or higher was associated with COVID-19 severity (P = 0.001). ・ 97.5% of newborns were tested negative for SARS-CoV-2 infection immediately after birth.	・ Obesity was associated with COVID-19 severity. ・ Disease severity was associated with higher rates of caesarean and preterm deliveries.
Lokken et al.; USA; 2021 [19]	Cohort study	240	・ Disease severity was linked to comorbidities or underlying conditions including asthma, hypertension, type 2 diabetes mellitus, autoimmune disease, and class III obesity. ・ The case fatality for COVID-19 was 13.6-fold higher in the pregnant population compared to individuals of a similar age. ・ Higher rates of preterm delivery were observed in women with severe or critical COVID-19 compared to women who had recovered from the infection.	・ Pregnant women are at risk of developing severe or critical disease and mortality from COVID-19 infection, compared to non-pregnant adults of similar age, as well as preterm birth.
Martinez-Perez et al.; 2021 [20]	Cohort study	246	・ Being SARS-CoV-2 positive increased the odds of preterm deliveries compared to non-infected mothers. ・ Infected women more commonly reported iatrogenic preterm births, but the occurrence of spontaneous preterm deliveries was similar statistically. ・ There was an increased risk of premature rupture of membranes at term and neonatal intensive care unit admissions in positive mothers.	・ Pregnant women who were COVID-19 positive demonstrated more infection-related obstetric morbidity.
Metz et al.; USA; 2021 [21]	Cohort study	1219	・ Disease severity was associated with older mean age, higher median body-mass-index, and pre-existing medical comorbidities. ・ Women with severe-critical COVID-19 had an increased risk of adverse perinatal outcomes like caesarean birth, hypertensive disorders of pregnancy and preterm deliveries compared to asymptomatic women. ・ Compared with asymptomatic patients, mild-moderate COVID-19 was not associated with adverse perinatal outcomes.	・ Pregnant women with severe-critical COVID-19, but not those with mild-moderate COVID-19 were at an increased risk of perinatal complications compared with asymptomatic pregnant patients.
Saccone et al.; Multinational (22 countries); 2020 [22]	Cohort study	388	・ 12.1% of women with a positive SARS-CoV-2 status had composite adverse maternal outcomes; 11.1% were admitted to the ICU, 9.3% required mechanical ventilation and 0.8% died. ・ Excluding the 122 women who were still pregnant at the time of data analysis, six had miscarriage, three had termination of pregnancy, six had stillbirth and 251 delivered a liveborn infant. ・ The preterm delivery rate was 26.3%. ・ Only one (0.4%) infant was found to be SARS-CoV-2 positive on RT-PCR.	・ SARS-CoV-2 infection during pregnancy was associated with a low maternal mortality rate, but an 11.1% rate of ICU admission. ・ The risk of vertical transmission may be negligible.
Taya et al.; Peru; 2020 [23]	Cohort study	247	・ 83% of the SARS-CoV-2 positive pregnancies were asymptomatic, with only 3.2% of them being severe. ・ Rates for caesarean deliveries were high (60%), while vaginal delivery rates had doubled over time. ・ Severe cases had higher rates of caesarean section and iatrogenic preterm delivery.	・ There is a higher possibility of caesarean and iatrogenic preterm deliveries in severe cases. ・ COVID-19 infection was not found to be linked to perinatal complications.
Villar et al.; Multinational (18 countries); 2021 [24]	Cohort study	706	・ Women infected with COVID-19 were at a higher risk for pre-eclampsia/eclampsia, severe infections, intensive care unit admission, maternal mortality, preterm birth, severe neonatal morbidity index, and severe perinatal morbidity and mortality index. ・ Any duration of fever and shortness of breath was associated with increased risk of severe maternal and neonatal complications ・ 13% of the neonates of COVID-19 positive mothers tested positive. ・ Caesarean deliveries but not breastfeeding was linked to an increased risk for neonatal test positivity.	・ When comparing pregnant women with and without COVID-19 diagnosis, a positive infection status was linked with increases in severe maternal morbidity and mortality and neonatal complications.
Vousden et al.; UK; 2021 [25]	Cohort study	1148	・ Women who were overweight or obese, of Black, Asian or other minority ethnic group, and having a relevant medical comorbidity, were more likely to be symptomatic for SARS-CoV-2 requiring hospitalisation, when compared to non-infected pregnant women. ・ Regardless of symptom status, there were increased rates of caesarean deliveries and neonatal unit admission.	・ Factors that increase the risk of symptomatic and asymptomatic SARS-CoV-2 in pregnancy have been identified. ・ The majority of women do not experience severe complications of SARS-CoV-2 in pregnancy.