Pregnant individuals are known to be at increased risk of worse outcomes from COVID-19 infection. Recent data suggests that they are also more likely to exhibit milder symptoms and have higher rates of asymptomatic infection. The health impacts of milder disease are less well-described but may include adverse perinatal outcomes. Serosurveillance can help describe accurately background rates of seropositivity in populations with high rates of asymptomatic infection. The seroprevalence of SARS-CoV-2 infection prior to vaccine availability was assessed in two large maternity centres. Of 437 pregnant individuals, seven were positive on initial screening, with one false positive identified on subsequent confirmatory testing. An overall seropositivity rate of 1.4% was found. No adverse pregnancy outcomes were identified. Confirmatory testing was performed with four commercial antibody-based assays and an in-house microneutralisation assay. Wantai SARS-CoV-2 receptor-binding-domain total antibody performed best, similar to previous reports. Serological surveillance can estimate infection rates not captured by acute PCR testing, and may assist with contact tracing, estimation of immunity rates and inform public health policy in at-risk groups. Evaluation of serological assays should be integrated into serosurveillance initiatives.

Objective: To determine the prevalence of pre-eclampsia and fetal growth restriction (FGR; <3rd centile) in women with pre-existing cardiac dysfunction. Design: Retrospective cohort study. Setting: Maternity units in UK and Australia. Population: Pregnant women with impaired left ventricular ejection fraction<55%. Methods: Routine clinical data, including medical history and pregnancy outcome were collected retrospectively. Main Outcome Measures: Pre-specified outcomes included pre-eclampsia and FGR prevalence in women with pre-existing cardiac impairment, compared with the general population; and the relationship between pregnancy outcome and pre-pregnancy cardiac phenotype. Results: In this cohort of 282 pregnancies, pre-eclampsia prevalence was not significantly increased (4.6% [95% C.I 2.2-7.0%] versus population prevalence of 4.6% [95% C.I. 2.7-8.2], p=0.99); 12/13 of these women had additional obstetric/medical risk factors. However, prevalences of preterm pre-eclampsia (<37 weeks) and FGR were increased (1.8% versus 0.7%, p=0.03; 15.2% versus 5.5%, p<0.001, respectively). Neither systolic nor diastolic function correlated with pregnancy outcome; however, left ventricular mass index (LVMi) weakly correlated with pre-eclampsia (5g/m2 increase: OR 1.18 [95% C.I. 1.01-1.38], p=0.04). Antenatal ß blockers (n=116) were associated with lower birthweight Z score (adjusted difference -0.33 [95% C.I. -0.63- -0.02], p=0.04). Conclusions: This study demonstrated a modest increase in preterm pre-eclampsia and significant increase in FGR in women with cardiac dysfunction. These results do not support a causal relationship between cardiac dysfunction and pre-eclampsia, especially accounting for the background risk status of the population. The mechanism underpinning the relationship between cardiac dysfunction and FGR merits further research but could be influenced by concomitant ß blocker use.

Objective: Universal screening has been proposed as a strategy to identify asymptomatic individuals infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and mitigate transmission. We aimed to investigate the rate of positive tests among pregnant women attending routine antenatal care. Design: Cross-sectional prevalence study. Setting: Antenatal clinic at three maternity hospitals (one tertiary referral hospital and two secondary maternities) in Melbourne, Australia. Population: Asymptomatic pregnant women attending routine antenatal care and pregnant women undergoing testing with symptoms of possible coronavirus disease. Methods: SARS-CoV-2 testing was offered to all pregnant women attending face-to-face antenatal visits and to those attending the hospital with symptoms of possible coronavirus disease, between 6th and 19th of May 2020. Testing was performed by multiplex-tandem polymerase chain reaction (PCR) on combined oropharyngeal and nasopharyngeal swabs. Main Outcome Measures: Proportion of positive SARS-CoV-2 tests. Results: SARS-CoV-2 testing was performed in 350 women, of whom 19 had symptoms of possible COVID-19. The median maternal age was 32 years (IQR 28 to 35 years), and the median gestational age at testing was 33 weeks and four days (IQR 28 weeks to 36 weeks and two days). All 350 tests returned negative results (p̂ = 0%, 95% CI 0 to 0.86%). Conclusion: The rate of asymptomatic coronavirus infection among pregnant women in Australia during the study period was negligible, which reflected reassuringly low levels of community transmission.