Prevalence of SARS-CoV-2 infection among obstetric patients in Ottawa, Canada: a descriptive study

Romina Fakhraei; Erica Erwin; Kameela M. Alibhai; Malia S.Q. Murphy; Alysha L.J. Dingwall-Harvey; Ruth Rennicks White; Sheryll Dimanlig-Cruz; Rosemary LaRose; Kimberly Grattan; Jian-Jun Jia; George Liu; Corey Arnold; Yannick Galipeau; Khatereh Shir-Mohammadi; Gillian D. Alton; Jessica Dy; Mark C. Walker; Deshayne B. Fell; Marc-André Langlois; Darine El-Chaâr

doi:10.9778/cmajo.20210228

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Figure 1:
Flow chart of study enrolment and sample collection. Note: NP = nasopharyngeal, OP = oropharyngeal, PCR = polymerase chain reaction. *Common reasons for nonparticipation are summarized in Appendix 1, Section 4.
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Figure 2:
Serology results of participants (n = 352). Participants with immunoglobulin (Ig) G antibodies against SARS-CoV-2 were considered seropositive.

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Table 1:

Sociodemographic, clinical and pregnancy characteristics of study participants

Characteristic	No. (%) of participants^* n = 362
Trimester at triage visit^†
1st (< 14 weeks’ gestation)	< 6 (S)
2nd (14–28 weeks’ gestation)	41 (11.3)
3rd (≥ 28 weeks’ gestation)	320 (88.4)
Symptoms consistent with COVID-19 upon admission to triage^‡	57 (15.7)
SARS-CoV-2 infection in pregnancy documented in medical chart^§	5 (1.4)
Maternal age, yr, mean ± SD	32.4 ± 4.9
Parity
0	166 (45.9)
≥ 1	195 (53.9)
Missing	< 6 (S)
Neighbourhood median family income quintile
1 (lowest)	51 (14.1)
2	80 (22.1)
3	73 (20.2)
4	80 (22.1)
5 (highest)	76 (21.0)
Missing	< 6 (S)
Race and ethnicity^¶
White	203 (56.1)
Asian	28 (7.7)
Black	26 (7.2)
Other	45 (12.4)
Missing	60 (16.6)
Prepregnancy BMI, median (IQR)	25.6 (21.9–30.3)
Obese (BMI > 30.0)^**
No	228 (63.0)
Yes	86 (23.8)
Missing	48 (13.3)
Substance use during pregnancy^††,^‡‡
No	323 (89.2)
Yes	35 (9.7)
Missing	< 6 (S)
Anxiety^‡‡
No	277 (76.5)
Yes	85 (23.5)
Depression^‡‡
No	311 (85.9)
Yes	51 (14.1)
Pre-existing maternal health conditions
None	306 (84.5)
Asthma	44 (12.2)
Chronic hypertension	7 (1.9)
Diabetes	7 (1.9)
Gestational diabetes
No	324 (89.5)
Yes	38 (10.5)
Hypertensive disorder in pregnancy^§§
No	314 (86.7)
Yes	48 (13.3)
Antenatal health care provider
Family physician only	24 (6.6)
Obstetrician only	252 (69.6)
Family physician and obstetrician	44 (12.2)
Midwife	31 (8.6)
Other provider	8 (2.2)
No provider	< 6 (S)
Missing	< 6 (S)
Number of fetuses
Singleton	345 (95.3)
Multiple	17 (4.7)
Gestational age at delivery, wk, median (IQR)	39.0 (38.0–40.0)
Preterm delivery (< 37 weeks’ gestation)
No	310 (85.6)
Yes	51 (14.1)
Missing	< 6 (S)
Mode of delivery
Vaginal	221 (61.0)
Cesarean	141 (39.0)
Missing	< 6 (S)
Birth outcome
Live birth	361 (99.7)
Intrapartum stillbirth	< 6 (S)

Note: BMI = body mass index, IQR = interquartile range, S = suppressed due to small cell size, SD = standard deviation.
↵* Unless indicated otherwise.
↵† Trimester of triage visit was calculated using the date that the patient was first enrolled in the study.
↵‡ Participant reported symptoms consistent with COVID-19 on Febrile Respiratory Illness Screening Tool used at hospital entry.
↵§ Participant had documentation of a positive SARS-CoV-2 laboratory test result that was reported during pregnancy and within time period of study.
↵¶ Information on race and ethnicity was obtained from the Ontario birth registry (Better Outcomes Registry & Network) and supplemented with medical chart review wherever possible. Racial and ethnic designations were assigned by the provider, sometimes through self-declaration by patients.
↵** BMI values below 10.3 and above 79.9 were excluded as outliers and set to missing for BMI grouping and obesity.
↵†† Substance use during pregnancy is defined as alcohol, drug or smoking during pregnancy.
↵‡‡ Self-reported variables obtained from the Ontario birth registry (Better Outcomes Registry & Network).
↵§§ Conditions include eclampsia, gestational hypertension, HELLP (hemolysis, elevated liver enzymes and low platelets), preeclampsia and pre-existing hypertension with superimposed preeclampsia.