Table 1.

Characteristics of SARS-CoV-2 included studies. * Initially presented as a decimal fraction. Calculated: when gestation at birth was calculated according to timeline of events, VD: vaginal delivery, CS: Caesarean section, H&E: haematoxylin and eosin, IHC: immunohistochemistry, TEM: transmission electron microscopy, PCR: polymerase chain reaction, NS: non-significant, MVM: maternal vascular malperfusion, FVM: fetal vascular malperfusion.

Study	Number of women	Clinical data	Mothers COVID- 19 Positive	Method of delivery and gestation at birth	Investigations	Results
Algarroba GN et al., 2020	1	Live female infant born due to deteriorating maternal condition, birthweight 1340 g, 5 min Apgar score of 5. Neonate tested negative.	Yes (unclear when tested) but came in with diagnosis.	CS 28 + 5 weeks (calculated)	PCR on neonatal samples. Placental histopathology TEM.	Placental histology: mature chorionic villi with focal villous oedema, decidual vasculopathy. Single virion in syncytiotrophoblast, single virion in microvillus, single virion found in core of terminal villus.
Algeri P et al., 2020	5	One case had gestational diabetes, two cases had ruptures of membranes. One case born severely premature. All infants were live born. Twins had low birth weight (<2500 g) and mother given corticosteroids. All neonates tested negative.	Yes, two cases diagnosed after delivery, three cases positive on admission.	4 CS, 1 VD, 27 + 4 to 38 + 4 weeks	One placenta sent to histology. PCR on four neonatal swabs (at birth and after 1 month)	Placental histology showed no signs of infection/inflammation, despite suspected chorioamnionitis during pregnancy. Bacterial swab of placenta was negative.
Baergen RN & Heller DS 2020	20 (1 set of twins)	Two mothers had preeclampsia and 1 had hypertension Two infants (2/10) were small for gestational age. All neonates tested negative.	Yes, all 20 tested positive (some asymptomatic) definitely at birth, 3 probably before.	5 CS, 15 VD 32 + 2 to 40 + 4 weeks	RT-PCR on neonatal samples, placental histopathology.	Placental histology: 9 fetal vascular malperfusion (3 intramural fibrin deposition in 1 or 2 foci, 2 villous stromal-vascular karyorrhexis, 4 multiple lesions), 3 cases with thrombi, 6 cases of meconium macrophages, 5 lesions of maternal vascular malperfusion, focal increase in perivillous fibrin deposition. One case of ascending infection with acute chorioamnionitis and acute funisitis. Four cases of chronic villitis (2 high grade, 1 associated with obliterative vasculopathy). In the twin case, one had a villous infarct and the other had high-grade chronic villitis. Eight cases with no gross umbilical cord abnormality associated with malperfusion.
Baud D et al., 2020	1	Nineteen weeks' gestation presented with contractions and fever. Bulging membranes on vaginal examination on admission. Stillborn infant born vaginally after 10 h of labour. Stillborn, birthweight not reported. Autopsy - no malformation.	Yes, 2 days before birth.	Miscarriage. VD 19 weeks	RT-PCR on amniotic fluid, fetal autopsy and fetal blood. Histology on placenta.	Fetal autopsy showed no malformations, and fetal lung, liver, and thymus biopsies were negative for SAR-CoV-2.Placental histology. Fetal surface was disinfected and sampled, samples tested positive. Histology showed monocytes and neutrophils in subchorial space, increased intervillous fibrin deposition, funisitis present. No bacterial or fungal infection. PCR was negative.
Chen S et al., 2020	3	Case 1: complete placenta previa Case 2: Acute cholecystitis, placental abruption Case 3: Complete placenta previa, scarred uterus. One preterm birth. All neonates tested negative.	Yes, 2 cases were positive (4 days and 2 days after delivery), one negative result but CT scan indicated SARS-CoV-2 infection (1 day after delivery).	3 CS 35–39 weeks	RT-PCR on neonatal swab. H&E of placenta, RT-PCR of full thickness placenta, membranes, and umbilical cord.	Placental histology: Placenta 1: chorionic haemangioma, fibrin in extravillous insterstitium, local end villous syncytial nodules increased. Placenta 2: infarction, increased interstitial and perivillous fibrin deposition with increased syncytial nodules. Placenta 3: interstitial and perivillous fibrin deposition. All three placentas tested negative for COVID-19.
Chen Siyu et al., 2020	5	Two with gestational diabetes, one with preeclampsia. All neonates tested negative. Apgar score of 10. No complications observed in the neonates.	All 5 positive, likely tested at or after birth.	3 VD, 2 CS 38 + 6–40 + 4 weeks.	qRT-PCR on neonatal samples. Placental histology.	Five placentas were histologically normal (no infarctions or chorionic amniotic inflammation).
Chen X et al., 2020	3	Case 1: the pregnancy was terminated 14 days after discharge. Case 2: pregnancy continued. Fetal growth was normal during the treatment but outcome unclear Case 3: emergency CS due to abnormal fetal heart rate but a healthy infant. Neonate tested negative. Methylprednisolone given to cases 2 and 3.	Yes, tested positive. Case 1: 30 days before termination. Case 2: unclear. Case 3:4 days after delivery.	1 third trimester CS, 1 termination of pregnancy, 1 unclear if delivered.	Examination of placenta, amniotic fluid and umbilical cord. PCR testing of placenta, umbilical cord blood, amniotic fluid and neonatal swab.	No abnormalities in the amniotic fluid, umbilical cord or placenta.
Dong L et al., 2020	1	No evidence of pregnancy complications. Corticosteroids administered. Normal birthweight, Apgar score of 10.	Yes, tested positive 3 weeks and 4 days before birth.	CS 37 + 6 weeks (calculated)	Neonatal IgM and IgG, cytokines. RT-PCR on nasopharyngeal swabs.	Neonate tested negative. Had significantly elevated IgM and IgG antibodies at 2 h old, also increased IL-6 and IL-10. IgM and IgG were still elevated at 2 weeks of age.
Fan C et al., 2020	2	No evidence of pregnancy complications. Corticosteroids administered. Normal birthweights, Apgar scores of 10.	Yes, Patient 1: tested positive 7 days before birth. Patient 2: tested positive 4 days before birth.	2 CS 36 + 5, 39 weeks	qRT-PCR on nasopharyngeal swab, cord blood, placenta tissue, amniotic fluid and placenta.	Placenta 1: placenta, cord blood and amniotic fluid tested negative. Placenta 2: “product of conception” was negative.
Ferraiolo A et al., 2020	1	No evidence of pregnancy complications. Apgar scores of 9–10.	Yes, positive after delivery.	CS 38 + 4 weeks	PCR on placental samples, neonatal swab at birth and 24 h. Anti-SARS-CoV-2 serology for IgM and IgG at 10 days old.	Neonate tested negative (first swab inconclusive, 24 h swab negative). 10 day serology tested negative. Placenta tested positive for RNA. Mild subchorionic deposition of fibrin, single ischemic area, focal haemorrhages in amniochorial membranes. Vessels in cord slightly hyperspiralized, no inflammation of membranes or funisitis. Delayed villous maturation. Terminal villi had capillary congestion and focal microchorangiosis. Modest fibrin deposition, villous agglutination, multiple organizing intervillous haemorrhage.
Grimminck K et al., 2020	1	Pre-existing hypertension and stable SLE (on azathioprine). Corticosteroids administered. Birthweight 30th centile (2880 g). Neonate tested negative.	Yes, tested positive on admission.	VD 38 + 2 weeks (calculated)	Maternal and fetal sides of the placenta were sampled. Neonatal oropharyngeal swab.	Placenta tested negative.
Hosier H et al., 2020	1	Severe preeclampsia with placental abruption. Maternal IgM and IgG were highest for any COVID-19 patient in the hospital. Severe hypertension upon admission (previous pregnancy complicated by gestational hypertension at term).	Yes, tested positive on admission.	Termination of pregnancy. 22 weeks	Serology for mother. IHC, in situ hybridisation and EM on placenta. PCR on the placenta and umbilical cord, placental histology, PCR on fetal autopsy.	Neonatal samples tested negative. Placental and cord tested positive for COVID-19 RNA. Placental histology: focal placental infarct (indicating abruption), diffuse perivillous fibrin, presence of macrophages and T cells, SARS-CoV-2 spike protein located in the syncytiotrophoblast, EM found viral particles in “cytosol of placental cells”.
Hsu AL et al., 2020	1	No evidence of pregnancy complications. Apgar scores of 8–9. Neonate tested negative.	Yes, 2 days before admission	VD 40 + 4 weeks	Neonatal PCR swab at 24 h, histopathology, IHC for SARS-CoV-2	Placental histology: no gross lesions, decidua had scattered arterioles and thickened smooth muscle (consistent with hypertropic arteriolopathy and subchorionic laminar necrosis). Focal lympho-histiocytic inflammation (consistent with chronic villitis), scattered island of extravillous trophoblasts. IHC found SARS-CoV-2 antigens throughout the placenta, under the umbilical cord, central and peripheral disc in chorionic villi endothelial cells, but rarely in trophoblast.
Huang JW et al., 2020	1	No evidence of pregnancy complications. Fetal distress prompted CS. Neonate alive, no detailed information. Neonate tested negative.	Yes, tested positive; unclear when.	CS 35 + 4 weeks (calculated)	SARS-CoV-2 nucleic acid testing of mother (stool and sputum), neonate (oropharyngeal swab). Cord blood, amniotic fluid, and placenta also tested.	All samples tested negative.
Kalafat E et al., 2020	1	No evidence of pregnancy complications. Single episode of reduced fetal movements. Normal birthweight (2790 g). Apgar score 9 at 5 min. Neonate tested negative.	Yes, tested positive 5 days before birth.	CS 36 + 1 weeks (calculated)	RT-PCR on placenta (“maternal and fetal sides”), cord blood and neonatal swabs.	All samples tested negative.
Kirstman M et al., 2020	1	Familial neutropenia, gestational diabetes, frequent bacterial infections. Apgar scores of 9 Neutropenic and mild hyperthermia so admitted to NICU after 37 h. All neonatal samples tested positive.	Yes, tested positive on admission (1 day before birth).	CS 35 + 5 weeks	Placental swabs of maternal and fetal sides for RT-PCR, histopathology, neonatal nasopharyngeal swab on day of birth, day 2 and day 7. Neonatal plasma on day 4.	Placenta tested positive. Placental histology: multiple areas of inflammatory cell infiltrates (CD68 macrophages, T cells, B cells and neutrophils) in the intervillous space consistent with chronic histiocytic intervillositis but differed: widespread infarction and clustering of inflammatory cells around chorionic villi.
Kuhrt K et al., 2020	1 (set of twins)	Twin pregnancy. Had a placental abruption, 400 ml retroplacental clot, significant intrauterine clots. Given dexamethasone for fetal lung maturation. Normal birthweight (twin one 2190 g, twin two 2160 g). Apgar score 8 and 9 at 5 min. Both twins tested negative.	Yes, tested positive two days before birth.	CS 32 + 6 weeks	PCR on neonatal samples. Placental histology.	Placental histology was clear of leukocyte invasion and fetal inflammatory response, but evidence of accelerated villous maturation, hypoperfusion noted, placental abruption.
Lang GJ et al., 2020	1	No evidence of pregnancy complications. Fetal distress prompted CS. Live birth, male, Apgar 9 and 10 at 1 and 5 min. Neonate tested negative.	Yes, tested positive 4 days before delivery.	CS 35 + 4 weeks (calculated)	RT-PCR on cord blood, amniotic fluid and placenta. Neonatal oropharyngeal swab.	All results were negative.
Lee DH et al., 2020	1	No evidence of pregnancy complications. Normal birthweight (3130 g). Apgar score 10 at 5 min. Neonate tested negative.	Yes, tested positive 1 week 4 days before birth.	CS 37 + 6 weeks	PCR on neonatal samples. RT-PCR on placenta, amniotic fluid and cord blood.	All samples tested negative.
Li Y et al., 2020	1	No evidence of pregnancy complications. Given methylprednisolone.Normal male infant “without complications”. Neonate tested negative.	Yes, tested positive 4 days before birth.	CS 35 + 4 weeks (calculated)	Neonatal oropharyngeal swab tested for RNA. Also tested the placenta, amniotic fluid and cord blood for RNA.	All samples tested negative.
Liu W et al., 2020	3 (1 tested the placenta)	One case had gestational diabetes. Case 1 and 2 received glucocorticoids. Normal birthweights (3250 g, 3250 g, 3670 g). All had Apgar scores of 9 at 5 min. Neonates tested negative.	Yes, all 3 tested positive, 1st patient on day of birth, 2nd patient day before birth, 3rd patient 3 days before birth.	2 CS, 1 VD 38 + 4–40 weeks	Only performed on one sample: RT-PCR on neonatal oropharyngeal swab RT-PCR on placental samples, cord blood, plasma serum and whole blood.	Cord blood tested negative, the results of placenta samples not mentioned.
Lokken EM et al., 2020	46 (only 1 examined)	No evidence of pregnancy complications apart from marginal cord insertion. Stillbirth.	Yes, tested positive on day of admission.	VD 38 + 4 weeks*	Culture of chorioamniotic membranes, microarray of fetus, histopathology, PCR of placental parenchyma and fetal nasopharynx, fetal autopsy.	SGA placenta, acute chorioamnionitis, severe chronic villitis, mild funisitis, no viral cytopathic changes (no viral inclusions). Placenta and fetal tissues negative for SARS-CoV-2 (but delay between fetal demise and testing), culture of membranes = normal genital flora.
Mulvey JJ et al., 2020	5	No evidence of pregnancy complications. No detailed neonatal information.	Yes, all 5 tested positive during intrapartum period.	4 VD, 1 CS 38–40 weeks	IHC for complement, spike IHC, viral RNA in situ hybridisation, histopathology (compared to normal VD as controls).	Placental histology: 5 x fetal vascular malperfusion, 5 x thrombosis in larger vessels, 4 x intramural fibrin deposition, 1 x vascular karyorrhexis, 1 x avascular villi, 1 x perivillous fibrin. Complement staining normal, viral protein/RNA rare, thrombosis in larger vessels (3x chorionic plate, 2x stem villi).
Nie R et al., 2020	33 (5 pregnancies ongoing and one termination of pregnancy).	Three cases of preterm prelabour rupture of membranes, 2 cases of hypertensive diseases of pregnancy, 2 cases of gestational diabetes mellitus, 1 woman had spontaneous preterm labour. 11 women received antenatal corticosteroids. 10 infants born preterm. Five had birthweight <2500 g. All Apgar scores at 5 min were 9 or 10. One infant (born 34 weeks' gestation) transferred to the NICU with a diagnosis of ARDS. One neonate tested positive.	Yes, all 33 tested positive (unclear when).	5 VD, 22 CS 1 termination of pregnancy, 5 ongoing pregnancies. 18 term, 9 preterm, 1 termination of pregnancy.	RT-PCR of neonatal throat swabs (26 tests), no mention of placenta or cord blood testing.	The placenta and cord blood of the positive neonate were negative.
Patanè L et al., 2020	22 (two neonates tested positive & the cases examined).	No evidence of pregnancy complications. Normal birthweights (2660 g and 2686 g). 5 min Apgar scores 9 and 10. Case 1 neonate tested positive immediately after birth. Case 2 neonate negative after birth but positive day 7.	Yes, 22 tested positive (two of the infants tested positive, and the cases examined) (unclear when, possibly at birth).	1VD, 1 CS 37 + 1* weeks and 37 + 4weeks*	H&E, IHC and in situ hybridisation on placentas for spike protein mRNA. RT-PCR on neonatal swabs.	Both placentas had chronic intervillositis, with macrophages in villi and intervillous space. IHC showed CD68 macrophages. In situ hybridisation shows antigen in the syncytiotrophoblast.
Penfield CA et al., 2020	11 (out of 32 positive women).	No evidence of pregnancy complications. All live born (no other data reported). All neonates tested negative.	Yes, all tested positive. For those with positive samples: up to 2 days before delivery. For negative samples: two tested positive at delivery, remainder between 1 and 15 days before delivery.	4 CS, 7 VD 26 + 5–41 + 3 weeks.	RT-PCR on placenta, membrane and neonatal swabs.	One placental sample and two membrane samples tested negative.
Peng Z et al., 2020	1	No evidence of pregnancy complications Single course of dexamethasone for fetal lung development. Normal birthweight (2600 g). Apgar score of 10.	Yes, tested positive one day before birth.	CS 35 + 3 weeks.	RT-PCR of amniotic fluid, placenta, cord blood. Gross histology of placenta, neonatal swabs.	The placenta looked normal, all samples tested negative for nucleic acids.
Pereira A et al., 2020	60 (23 delivered, 6 placentas tested)	3 cases of pre-eclampsia, 2 premature deliveries, 5 CS (1 for maternal respiratory failure, breech position, 2 for non-progression of labour, 1 induction failure, 1 for HELLP syndrome). Two NICU admissions, 3 with FGR. 23 newborns tested negative.	All 23 tested positive, unclear when.	18 VD, 5 CS 21 term births, two preterm.	Neonates tested for SARS-CoV-2 by RT-PCR nasopharyngeal swabs, placentas tested by RT-PCR.	All six placentas tested negative.
Prabhu M et al., 2020	70	All the infants who were tested were negative. Preterm labour or preterm premature rupture of membranes: positive mothers: 3 (1.4%), negative mothers: 25 (4.1%). Chronic hypertension positive mothers: 3 (1.4%), negative mothers: 13 (2.1%). Pre-eclampsia or gestational hypertension positive mothers: 11 (15.7%) negative mothers: 56 (9.3%). Pregestational diabetes positive mothers: 4 (5.7%) negative mothers: (1.2%). Gestational diabetes positive mothers: 6 (8.6%) negative mothers: 54 (8.9%). Preterm birth positive mothers: 11 (15.7%) negative mothers: 57 (9.4%). One case admitted to ICU for hypoxia (delivered via NVD 3 days later). Multiple gestations positive mothers: 4 (5.7%) negative mothers: 15 (2.5%).	Yes, all cases tested positive at admission.	38 VD, 32 CS Median 38 + 4 weeks* (IQR: 37+2–39 + 6)*	Placental histology compared to 605 SARS-CoV-2 negative women. Placental histology: 29 placentas compared to 106 placentas from SARS-CoV-2 negative women.	FVM noted in 14 cases (48.3%) from cases, and 12 from controls (11.3%, p < 0.001). These has thrombi in the fetal vessels. MVM in 8 cases (27.6%) and 33 controls (31.1%, NS). Evidence of chorioamnionitis maternal and fetal response in 2 cases (6.9%) and 7 from controls (6.6%, NS). Chronic villitis (low grade) in 2 cases (6.9%) and 9 controls (8.5%). High grade in 3 cases (10.3%) and 4 controls (3.8%), both not significant. Umbilical cord abnormalities in 1 case (3.4%) and 17 controls (16% NS). Chorangiosis in 0 cases (0%) and 1 control (0.9%, NS). Other placental abnormalities 3 cases (10.3%) and 10 controls (9.4%, NS). One infant from SARS-CoV-2 positive mother was stillborn at 37 weeks (poorly controlled type 2 diabetes, normal placental pathology, no autopsy).
Pulinx B et al., 2020	1	Twin pregnancy. Gestational diabetes, one intrauterine death, one prepartal death.	Yes, tested positive 2 weeks before birth.	VD 24 weeks	RT-PCR on both placentas, amniotic fluid sample and amniotic sac IHC for macrophages, T cells and SARS-CoV-2. Morphology by three pathologists.	Both placentas tested negative and the amniotic fluid tested positive (tested as whole as VD). Amniotic sacs tested negative. Both placentas had extensive intervillous fibrin deposition, ischemic necrosis of surrounding villi, aggregates of histiocytes and T cells in the intervillous space (diagnosis of chronic intervillositis). Viral localisation in syncytiotrophoblast.
Richtmann R et al., 2020	5	Two cases were obese, three cases were overweight. All infants were stillborn.	Yes, tested positive between 22 days before birth and at admission.	3 VD, 2 CS 21+1–38 + 3 weeks	Histopathologist blinded to SARS-CoV-2 status. Histopathology on placenta and amniotic fluid tested for SARS-CoV-2	Case 1: Placental fragments tested positive. Pathology: acute chorioamnionitis, extensive perivillous fibrin deposition and acute villitis, findings suggestive of villitis of unknown etiology. No fetal autopsy. Case 2: no fetal malformations, fetal and placental histology showed signs of acute infection: extensive perivillous fibrin deposition, acute villitis and intervillositis. focal acute chorioamnionitis. Findings suggestive of ischemia and villitis. Case 3: placenta tested negative, amniotic fluid inconclusive. Pathology: acute chorioamnionitis, subchorionic thrombosis, findings suggestive of ischemia and infection. No fetal autopsy. Case 4: placenta and amniotic fluid not tested. Acute chorioamnionitis, acute deciduitis, findings suggestive of ischemia and infection. No fetal autopsy. Case 5: Placenta and amniotic fluid tested positive. Acute chorioamnionitis. Acute deciduitis. No fetal autopsy.
Semeshkin AA et al., 2020	20	One set of twins. No maternal information provided. All neonatal Apgar scores 8–10. All neonates tested negative via nasopharyngeal swab.	Yes, all on admission.	16 VD, 4 CS Gestation not provided	IgM and IgG antibodies in maternal and neonatal serum on days 1 or 2 after birth. Neonatal nasal and nasopharyngeal swab on day 1 or 2 after birth	Antibodies detected in all samples. IgM and IgG were raised in one case. IgM and IgG were in range for 4 neonates (levels similar to mothers). IgG was raised 14 neonates, their mothers had high titres of IgG and IgM outside of reference range. All neonates had IgG antibodies in their serum. IgG was elevated in 16 neonates, but only in cases where maternal levels were also elevated.
Shanes ED et al., 2020	16	One case of gestational diabetes and obstetric cholestasis, one with hypertensive disorders. One 16- week fetal death with preterm prelabour rupture of membranes, one preterm birth at 34 weeks' gestation. All neonates were negative including IUFD.	All tested positive; 6 x on day of birth, 2 × 1 day, 1 × 2 days, 1 × 7 days, 1 × 8 days, 2 × 25 days, 1 × 28 days, 1 x 34 days. IUFD on date of birth.	15 not specified, 1 IUFD 14 term births, one 34 weeks, one 16- week IUFD.	Placental histology compared to historical normal controls, also used controls with history of melanoma, neonatal nasopharyngeal swabs tested by PCR.	IUFD placenta: retroplacental haematoma, villous oedema, villous maturation was appropriate. No acute or chronic inflammation. 15 cases compared to controls:: Total: 11 some features of MVM, 12 with some features of FVM 11 x maternal vascular malperfusion, 1 x central infarct, 3 x peripheral villous infarct, 3 x villous agglutination, 3 x atherosis and fibrinoid necrosis of maternal vessels, 5 x hypertrophy of membrane arterioles, 2 x accelerated villous maturation, 12 x fetal vascular malperfusion, 4 x clustered avascular villi, 1 x fibrin deposition in fetal vessels, 4 x delayed villous maturation, 3 x hypercoiled cord, 4 x choroangiosis, 1 x acute inflammatory pathology, 2 x chronic inflammatory pathology, 3 x perivillous fibrin deposition.
Sisman J et al., 2020	1	Type 2 diabetes, obesity, late latent syphilis, premature preterm rupture of membranes. Normal birthweight, Apgar scores 7–9, went to NICU for monitoring (IVIG for suspected ABO incompatibility). Neonate tested positive at 24, 48 h and 14 days after birth.	Tested positive 3 days before birth.	VD 34 weeks	Neonatal nasopharyngeal swab at 24 and 48 h, placental histopathology, IHC for CD68 and SARS-CoV-2. TEM	Placental histology: patchy histiocytic intervillositis and villous associated with villous karyorrhexis and necrosis, focal basal chronic villitis, focal parabasal infarct and features of meconium exposure in the fetal membranes. SARS-CoV-2 nucleocapsid in syncytiotrophoblast. TEM: 89–129 nm structures clustered within “membrane bound cisternal spaces” in the syncytiotrophoblast.
Smithgall MC et al., 2020	51	Positive mothers: 21 women had comorbidities (41.2%), negative mothers: 12 (48%, NS). Apgar scores >7. All neonates tested negative.	Yes, tested on admission.	26 VD, 25 CS 10 born <37 weeks, 41 born > 37 weeks.	Compared to 25 SARS-CoV-2 negative women. Neonates to positive mothers tested by nasopharyngeal swab. Placentas grossly examined, umbilical cord, membranes and placenta were examined. In situ hybridisation or IHC for placentas from positive women.	32 placentas tested by in situ hybridisation and IHC, 5 by in situ hybridisation and 14 with IHC. No viral cytopathic changes, all negative. Placental pathology: Ascending uterine infection maternal response cases: 33.3%, 36% controls. Fetal response cases: 17.7%, controls: 12% (NS). MVM: any mention of MVM in 58 placentas (cases) and 17 placentas (controls) NS. FVM total: any mention of FVM 17 (cases) and 2 (controls) (NS). Significantly more villous agglutination in cases vs controls (41.2% vs 8%, p = 0.003) and significantly more subchorionic thrombus (17% vs 0%, p = 0.026). Chronic villitis of unknown etiology in 2 cases and 2 controls (NS).
Vivanti AJ et al., 2020	1	No evidence of pregnancy complications. Neonatal Apgar scores 4, 2 and 7. Intubated on NICU. Birthweight 2540 g. Neonate tested positive in all samples.	Yes, on admission (3 days before birth)	CS 35 + 5 weeks	Neonatal blood and bronchoalveolar lavage, nasopharyngeal and rectal swabs at 1 h of life, repeated at day 3 and 19. RT-PCR on placenta and amniotic fluid. IHC of placenta for SARS-CoV-2. Placental histology.	Amniotic fluid tested negative. Placental tested positive (highest viral load of any of the samples). Placental pathology: diffuse perivillous fibrin deposition, infarction, acute and chronic intervillositis (CD68 macrophages). Cytoplasm of trophoblast positive for N protein by IHC.
Wang S et al., 2020	1	No evidence of pregnancy complications. Methylprednisolone postnatally. Live male infant, normal birthweight (3205 g). Apgar score of 9 at 5 min. Fetal throat swab positive.	Yes. Tested positive same day after birth.	CS 40 + 1 weeks (calculated)	PCR on neonatal swabs, cord blood, amniotic fluid placental samples.	Cord blood, placental samples tested negative.
Wang X et al., 2020	1	No evidence of pregnancy complications. Dexamethasone and magnesium sulphate as fetal prophylaxis. Live male infant, normal birthweight (1870g). Apgar score of 10 at 5 min. Neonate tested negative.	Yes. Tested positive 3 days before birth.	CS 30 weeks	RT-PCR of amniotic fluid, cord blood, placenta, throat swab of neonate.	Placenta, amniotic fluid, cord blood all tested negative
Xiong X et al., 2020	1	No evidence of pregnancy complications Corticosteroid therapies given. Live infant, normal birthweight (3070 g). Five minute Apgar score of 10. Neonate was negative.	Yes, tested positive 5 weeks 2 days before birth.	VD 38 + 4 weeks	Maternal throat swab tested for COVID though RT-PCR. Neonatal IgM and IgG, PCR of amniotic fluid and neonatal throat and rectal swabs, Protein N in placenta, pathological analysis of placenta.	Amniotic fluid was negative, Placenta was negative for N protein of SARS-CoV-2 and there was no inflammation, neonatal IgM and IgG were negative.
Yu N et al., 2020	7	Increased fetal movement in one pregnancy. 6 pregnancies had no pregnancy complications 5/7 patients given methylprednisolone postnatally. All infants live born with normal birthweight (3000–3500 g). All 5 min Apgar scores 9–10. One neonate tested positive after 36 h.	Yes, all 7 tested positive; 4 x on day of birth, 1 × 1 day, 1 × 2 days, 2 x 3 days.	7 CS 37-41 + 5 weeks	Maternal Covid infection Dx with throat swap though RT-PCR. Nucleic acid test on neonate (x3) and placenta and cord blood (unclear how many samples).	Placenta and cord blood tested negative for the positive neonate.
Yin M-Z et al., 2020	31 (17 births, 3 termination of pregnancies)	One pregnancy with hypertension, one with diabetes, one cardiovascular disease. 35% of the 31 women received glucocorticoid therapies. One low birth weight (<2500 g) in premature birth. Apgar score between 7 and 8 at 1 min, between 8 and 9 at 5 min. All 17 neonates tested negative.	All 17 tested positive, unclear when.	13 CS, 4 VD 35–41 weeks	RT-PCR on amniotic fluid (x2), placenta (x2), 17 neonatal throat swabs. Maternal throat swabs.	All samples tested negative.
Zeng H et al., 2020	6	No evidence of pregnancy complications. All infants live born with 5 min Apgar scores 9–10. All neonates tested negative.	Yes, unclear when.	6 CS All third trimester	RT-PCR maternal and neonatal throat swabs and blood samples. Cytokine profiling, and IgM and IgG analysis of neonatal serum. Also, IgG and IgM for maternal serum.	Four mothers had high serum IgG and IgM. One mother with only raised IgG. All 6 neonates had virus-specific antibodies in their serum. Two samples had high IgG and IgM, three neonates had high IgG but normal IgM. IL-6 increased in all neonates.