Interpretation
There have been limited studies looking at COVID-19 in the pregnant population.
When a new pathogen emerges we can look to previous pandemics for insight into the natural history and course of the disease. With previous coronavirus spectrum infections serious acute respiratory syndrome (SARS) and middle eastern respiratory syndrome (MERS) there was a higher incidence of preterm birth, pre-eclampsia and caesarean section than in the general population . In addition, the clinical outcomes were worse for pregnant women than non-pregnant women, with a high incidence of death, renal failure, and disseminated intravascular coagulopathy .
By contrast, SARS-CoV-2 does not appear to have worse clinical outcomes for pregnant women compared to non-pregnant women. In a recent case series of 158 patients who tested positive for SARS-CoV-2 in New York, 78% had mild or asymptomatic disease . This is comparable to a study of 118 SARS-CoV-2 positive pregnant patients in Wuhan, 92% of whom had mild disease . In both settings, the risk of severe disease was similar to that of the general population, and appears to be associated with medical co-morbidities and increasing age.
COVID-19 is known to be a pro-coagulopathic state, with significantly higher rates of venous thromboembolism than in the general population . One might therefore expect evidence of thrombotic complications in the placentas of obstetric patients infected with COVID-19. Indeed, histopathological examinations of these placentas have demonstrated that they are more likely to show features of maternal vascular malperfusion (MVM) . These findings may suggest that these patients are at a higher risk of complications of poor placental perfusion, and warrant increased surveillance. Placental abruption ranges from the subclinical to massive catastrophic cases, histological assessment of all placentas throughout the pandemic period may have revealed many more cases of sub clinical abruption, but resources limit the ability to perform this in an initial review. We may therefore be underestimating the frequency of abruptions, and thus the impact of the disease.
Khalil et al studied the incidence of stillbirth and preterm birth at St George’s Hospital, London during the pandemic period (1st Feb 2020 to 14th June 2020) and the pre-pandemic period (1st Oct 2019 to 31st Jan 2020). Investigators found a significantly higher incidence of stillbirth during the pandemic period compared to the pre-pandemic period . Similar to our review, none of their patients had tested positive to SARS-CoV-2. Although the results were significant, they could not infer direct causality between asymptomatic SARS-CoV-2 and stillbirth. Other possible explanations include a reluctance of patients to attend hospital for fetal concerns, or a change in the available obstetric services during the pandemic period.
Despite none of our patients testing positive for SARS-CoV-2 there was a significantly lower lymphocyte count in 2020 compared to 2019. Lymphopaenia is known to be a cardinal feature of COVID 19. In the obstetric population, lymphopaenia is associated with moderate or severe disease . If we could consider lymphopaenia a proxy for SARS-CoV-2 infection, our preliminary findings could suggest an association between COVID-19 and IUD.
Learning from previous epidemics, it is widely acknowledged that services for women and children are especially vulnerable to disruption. In the 2014 Ebola outbreak in west Africa there was a 44% reduction in inpatient services, with similar reductions in antenatal and postnatal services, and family planning availability . Analysis of Sierra Leone’s Health Management Information System found that the Ebola epidemic lead indirectly to 3,600 additional maternal deaths, neonatal deaths, and stillbirths . Similarly, during the COVID-19 pandemic, we have seen restructuring of services to prioritise acute care of those affected. This was compounded by fear of contracting the disease, healthcare provider sickness, and disruption to the global medical supply chain. Because of this, estimates of indirect maternal deaths during the COVID-19 outbreak in low- and middle-income countries lie between 8.3-38.6% . It is therefore likely that some aspect of the rise in IUD that we have seen is an indirect, rather than direct, result of COVID-19.