Association of antepartum and intrapartum SARS-CoV-2 infection on
pregnancy outcomes in South African women, two observational studies
Objective: Evaluate the impact of the timing of SARS-CoV-2 infection on
pregnancy outcomes in a low-middle income setting. Design: two parallel,
observational studies. Setting and population: pregnant women or women
presenting for labour, enrolled between April-September 2020, in South
Africa. Methods: i) longitudinal follow-up study of symptomatic or
asymptomatic pregnant women investigated for SARS-CoV-2 infection
antenatally, ii) cross-sectional study of SARS-CoV-2 infection at time
of labour. SARS-CoV-2 infection was investigated by nucleic acid
amplification test (NAAT). Main Outcome Measures: association of
SARS-CoV-2 infection on nasal swab and birth outcomes. Results:
Antenatally, 793 women were tested for SARS-CoV-2. Overall SARS-CoV-2
infection was confirmed in 138 women, including 119/275 with symptomatic
illness (COVID-19) and 19/518 asymptomatic women; 493 women were
asymptomatic and SARS-CoV-2 non-reactive. Women with COVID-19 were
1.66-times (95%CI: 1.02, 1.71) more likely to have a low-birthweight
newborn (30%) compared to asymptomatic women without SARS-CoV-2 (21%).
Overall, 3117 women were tested for SARS-CoV-2 infection at delivery,
including 1560 healthy women with an uncomplicated term delivery.
Adverse birth outcomes or pregnancy-related complications were not
associated with infection at delivery. Among women with SARS-CoV-2
infection at delivery, NAAT was reactive on 6/98 of maternal blood
samples, 8/93 of cord-blood, 14/54 of placentas and 3/22 of
nasopharyngeal swabs from newborns collected within 72-hours of birth.
Conclusions: Antenatal, but not intrapartum, SARS-CoV-2 infection was
associated with low-birthweight delivery. Maternal infection at the time
of labour was associated with in utero foetal and placental infection,
and possible vertical and/or horizontal viral transfer to the newborn.