Questionnaires were sent to 2,185 medical facilities with maternity services. Responses were received from 1,418 (64.9%) facilities with a recorded total of 611,444 deliveries in 2019 (71.1% of all deliveries in Japan). The positive rate of the universal SARS-CoV-2 screening among asymptomatic pregnant women during the study period was 0.03% (2/7428).
The study flow is shown in Fig. 1. Seventy-four pregnant women with confirmed COVID-19 were treated in 48 institutions between 16 January and 30 June 2020. Of these, one case was a duplicate record and another had missing data. Hence, 72 women with complete data were included in this analysis, of whom 58 (80.6%) were symptomatic and 14 (19.4%) were asymptomatic.
The maternal characteristics of symptomatic and asymptomatic COVID-19 patients are shown in Table 1.
Table 1
Maternal characteristics of symptomatic and asymptomatic COVID-19 patients
|
Symptomatic patients (n = 58)
|
Asymptomatic patients (n = 14)
|
P-value
|
Maternal age
|
|
|
|
Median (interquartile range)
|
31 (27–36)
|
32 (25–33)
|
0.41
|
Under 20
|
0 (0%)
|
0 (0%)
|
> 0.99
|
20–29
|
20 (34.5%)
|
6 (42.9%)
|
0.59
|
30–39
|
33 (56.9%)
|
8 (57.1%)
|
> 0.99
|
over 40
|
5 (8.6%)
|
0 (0%)
|
0.33
|
Approach for diagnosis
|
|
|
|
Symptom
|
57 (98.3%)
|
0 (0%)
|
< 0.001
|
Contact with confirmed or suspected patients
|
1 (1.7%)
|
12 (85.7%)
|
< 0.001
|
Universal screening
|
0 (0%)
|
2 (14.3%)
|
0.04
|
Pregnancy period at diagnosis
|
|
|
|
1st trimester
|
12 (20.7%)
|
3 (21.4%)
|
0.60
|
2nd trimester
|
28 (48.3%)
|
4 (28.6%)
|
0.22
|
3rd trimester
|
15 (25.9%)
|
5 (35.7%)
|
0.38
|
Postpartum
|
3 (5.2%)
|
2 (14.3%)
|
0.25
|
Epidemiological history
|
|
|
|
Familial infection
|
33 (56.9%)
|
8 (57.1%)
|
> 0.99
|
Community-acquired
|
5 (8.6%)
|
3 (21.4%)
|
0.18
|
Visiting and staying in infected areas
|
4 (6.9%)
|
0 (0%)
|
0.41
|
Nosocomial infection
|
2 (3.4%)
|
1 (7.1%)
|
0.48
|
Workplace infection
|
1 (1.7%)
|
2 (14.3%)
|
0.10
|
Unknown
|
13 (22.4%)
|
0 (0%)
|
0.05
|
Comorbidities
|
|
|
|
Gestational diabetes
|
5 (8.6%)
|
0 (0%)
|
0.33
|
Preeclampsia
|
1 (1.7%)
|
0 (0%)
|
0.81
|
Asthma
|
3 (5.2%)
|
0 (0%)
|
0.52
|
Course of pregnancy a
|
|
|
|
Pregnancy ongoing
|
29 (50.0%)
|
7 (50.0%)
|
> 0.99
|
Delivery
|
21 (36.2%)
|
5 (35.7%)
|
0.97
|
Delivery during infection
|
9 (15.5%)
|
3 (21.4%)
|
0.43
|
Spontaneous abortion
|
2 (3.4%)
|
0 (0%)
|
0.65
|
Induced abortion
|
1 (1.7%)
|
0 (0%)
|
0.81
|
Prognosis of mother
|
|
|
|
Recovered without subsequent complication
|
57 (98.3%)
|
14 (100%)
|
0.81
|
Death
|
1 (1.7%)
|
0 (0%)
|
0.81
|
Data indicate n (%) |
a: Excluding 1 maternal death, 1 case of missing data, and 5 cases of puerperium diagnosis |
The median maternal ages of symptomatic and asymptomatic patients were 31 (interquartile range [IQR], 27–36) and 32 (IQR, 25–33) years, respectively. Among asymptomatic patients, 85.7% had been tested after having been in contact with confirmed or suspected individuals and 14.3% were tested during universal screening. The majority of symptomatic patients were diagnosed during the second trimester (46.6%), while the majority of asymptomatic patients were diagnosed during the third trimester (35.7%). In both groups, the most common route of infection was familial (56.9% for symptomatic patients and 57.1% for asymptomatic patients). Only one asymptomatic patient (1.7%), a tourist from Europe, died due to COVID-19.
The maternal clinical presentation of symptomatic COVID-19 patients is shown in Table 2.
Table 2
Maternal clinical presentation of symptomatic COVID-19 patients (n = 58)
Signs and symptoms
|
|
Fever
|
41 (70.7%)
|
37.0–38.0 (°C) a
|
26 (44.8%)
|
38.0–39.0 (°C) a
|
13 (22.4%)
|
Cough, respiratory distress, or sore throat
|
39 (67.2%)
|
Taste and smell disorders
|
23 (39.7%)
|
Fatigue
|
17 (29.3%)
|
Muscular pain
|
4 (6.9%)
|
Headache
|
4 (6.9%)
|
Nasal discharge and nasal congestion
|
2 (3.4%)
|
Diarrhea
|
2 (3.4%)
|
Itchy throat
|
1 (1.7%)
|
Severe respiratory symptoms
|
5 (8.6%)
|
Chest CT examination
|
|
Performed during pregnancy
|
17 (32.8%)
|
Radiologically confirmed pneumonia
|
12 (20.9%)
|
Treatments
|
|
Hospitalization
|
48 (82.8%)
|
Time from symptom onset to hospitalization (days) b
|
6 (2–10)
|
Time from hospitalization to worsening of symptoms (days) c
|
0 (0–4)
|
Oxygen administration
|
10 (17.2%)
|
Intensive care unit admission
|
3 (5.2%)
|
Invasive mechanical ventilation
|
1 (1.7%)
|
Data indicate n (%) or median (interquartile range); CT: computed tomography |
a: Excluding 3 cases with missing data |
b: Excluding 3 cases with missing data |
c: Excluding 9 cases with missing data |
The most common symptoms were fever (70.7%) and cough, respiratory distress, or sore throat (67.2%). Five patients (8.6%) had severe respiratory symptoms. Seventeen women (32.8%) underwent a chest CT scan during pregnancy, and 12 (20.9%) had radiologically confirmed pneumonia. Forty-eight (82.8%) were hospitalised and the time from symptom onset to hospitalisation was a median of 6 days (IQR, 2–10). Ten women (17.2%) required oxygen administration and three (5.2%) were admitted into the ICU. One woman (1.7%) needed mechanical ventilation and later died.
A total of 24 infected women delivered infants during the study period. Of these, 12 deliveries occurred during active infection while the others occurred after recovery. Perinatal outcomes of COVID-19 patients who delivered during infection are shown in Table 3. Nine women were symptomatic and three were asymptomatic. All 12 women underwent caesarean sections, with 11 of them performed owing to concerns about the effects of COVID-19 on pregnancy. All 12 women delivered live infants, and no severe neonatal asphyxia was observed. Eleven newborns were tested for SARS-CoV-2 using nasal and pharyngeal swabs, and all tested negative. None of the infants born to these women suckled; one infant received expressed breast milk, while the others were given formula milk. In all the cases, the mother and baby were separated while in hospital.
Table 3
Perinatal outcomes of symptomatic and asymptomatic COVID-19 patients who delivered during infection
|
Symptomatic patients (n = 9)
|
Asymptomatic patients (n = 3)
|
P-value
|
Timing of delivery
|
|
|
|
Gestational age at delivery (weeks and days)
|
38w4d (36w5d-38w6d)
|
37w5d (37w2d-39w4d)
|
0.93
|
Preterm birth
|
2 (22.2%)
|
0 (0%)
|
0.55
|
Due to iatrogenic causes
|
2 (22.2%)
|
0 (0%)
|
0.50
|
Mode of delivery
|
|
|
|
Vaginal delivery
|
0 (0%)
|
0 (0%)
|
> 0.99
|
Induction of labour
|
0 (0%)
|
0 (0%)
|
> 0.99
|
Caesarean section
|
9 (100%)
|
3 (100%)
|
> 0.99
|
Due to obstetrical indications
|
1 (11.1%)
|
0 (0%)
|
|
Due to concern about COVID-19
|
8 (88.9%)
|
3 (100%)
|
|
Neonatal outcome
|
|
|
|
Apgar score < 7 at 1min
|
0 (0%)
|
0 (0%)
|
> 0.99
|
Apgar score < 7 at 5min
|
0 (0%)
|
0 (0%)
|
> 0.99
|
Birth weight (g)
|
2950 (2549–3105)
|
3110 (2805–3109)
|
0.21
|
Performed SARS-CoV-2 test
|
9 (100%)
|
2 (100%)a
|
> 0.99
|
Confirmed Positive
|
0 (0%)
|
0 (0%)
|
> 0.99
|
Breastfeeding
|
1 (11.1%)
|
0 (0%)a
|
0.82
|
Mother-Neonate Separation
|
9 (100%)
|
3 (100%)
|
> 0.99
|
Data presented as n (%) or medians (interquartile ranges)
a: Data was not available for one patient as delivery had just occurred at the time of data collection
SARS-CoV-2: severe acute respiratory syndrome coronavirus 2
COVID-19: coronavirus disease 2019
The maternal outcomes of symptomatic patients in each pregnancy period are shown in Table 4. Severe respiratory symptoms, oxygen administration, and radiologically confirmed pneumonia were frequently reported in the third trimester and postpartum period compared with those in early pregnancy (22.2% vs 2.5% [P = 0.03], 38.9% vs 7.5% [P = 0.01], and 50.0% vs 7.5% [P < 0.01], respectively).
Table 4
Maternal outcomes of symptomatic patients during each pregnancy period
|
1st or 2nd trimester (n = 40)
|
3rd trimester or puerperium (n = 18)
|
P-value
|
Respiratory rate > 30/min.
|
1 (2.5%)
|
3 (16.7%)
|
0.08
|
SpO2 < 93%
|
1 (2.5%)
|
3 (16.7%)
|
0.08
|
PaO2/FiO2 ratio less than 300
|
1 (2.5%)
|
0 (0%)
|
0.69
|
Severe respiratory symptoms
|
1 (2.5%)
|
4 (22.2%)
|
0.03
|
Oxygen administration
|
3 (7.5%)
|
7 (38.9%)
|
0.01
|
Radiologically confirmed pneumonia
|
3 (7.5%)
|
9 (50.0%)
|
< 0.001
|
Data presented as n (%)
SpO2: Percutaneous oxygen saturation
PaO2: Arterial oxygen partial pressure
FiO2: Inspired oxygen fraction