This prospective and exploratory study report the prevalence of COVID-19 in pregnancy and its impact on maternal and perinatal health in the obstetric population of Maputo, Mozambique. The overall prevalence of COVID-19 in pregnant and postpartum women was 9.2%. Almost half of the population was asymptomatic at the time of diagnosis. In addition, the sociodemographic and gestational factors commonly associated with greater vulnerability to SARS-CoV-2 infection were being pregnant, alcohol consumption, and not having a partner.
These data suggest that the overall prevalence of COVID-19 in pregnant and postpartum women is higher than the general Mozambican population, which was 2–4 % (25). Likewise, this prevalence is relatively higher than that of the study in pregnant and postpartum women, also carried out in Maputo city (21). The difference in the COVID-19 prevalence might be due to the testing strategy, as the studies previously conducted in Mozambique (in general and obstetric population) were seroepidemiologic, and the COVID-19 pandemic magnitude in the country at the time of the studies implementation.
Conversely, our findings are similar to the results of the systematic review by Allotey and colleagues and another epidemiological study carried out in Zambia, which estimated an overall prevalence of COVID-19 in pregnant and postpartum women of 10% and 11.7%, respectively (15, 26).
The prevalence of COVID-19 was 32.4 % in the group of symptomatic women at study admission. These findings are similar to other studies in which testing was based on clinical symptoms (15, 27). Therefore, these data reinforce that the best testing approach is universal in places where resources are available to ensure proper management of pregnant women and newborns once even asymptomatic patients have an increased risk of maternal outcomes, maternal morbidity (RR, 1.24; 95%CI, 1.00-1.54) and preeclampsia (RR, 1.63; 95%CI, 1.01–2.63)(28).
Our data reinforce that SARS-CoV-2 infection is associated with an increased risk of adverse obstetric outcomes, such as foetal death. (RR = 4.0 [1.19–13.48]) and abortion/ stillbirth 12.0 [7.7–18.7]. These findings are similar to the systematic review, which estimated increased risk of stillbirth OR 1·29 (1·06–1·58)(14) and RR 2.84 (1.25–6.45)(15). The higher risk of adverse maternal outcomes observed in our cohort may be due to the third delay (receiving adequate and appropriate treatment)(29). Given that two-thirds of the participants in our study had at least four antenatal care, this delay might have been exacerbated by the COVID-19 pandemic.
We did not observe significant differences in the risk of admission to the intensive care unit, development of severe acute respiratory syndrome, preeclampsia, prematurity, NICU admission and neonatal death between the exposed and non-exposed groups. Our data are similar to systematic reviews (14, 30) and individual studies (28). On the other hand, our findings differ from those of other published studies for maternal ICU admission outcomes, preeclampsia, which increased risk in pregnant women with COVID-19 (30, 31).
The major limitation of this study is related to the sample size. The sample size was small as it might not have the power to detect a difference between the exposure and non-exposure groups for some maternal and perinatal outcomes. Furthermore, although we have estimated a sample size of 300 participants (pairs of pregnant women and newborn), a scarcity of laboratory supplies (SARS-CoV-2 GeneXpert cartridges) at the national level hindered the study implementation. Therefore, reinforcing the difficulty of implementing prospective studies in places with few resources. In addition, the scarcity of SARS-CoV-2 GeneXpert cartridges might have influenced the lower test per COVID-19 case ratio de 5.8 observed in Mozambique, which is almost half of the recommended ratio.
The second limitation would be related to the testing strategy for the asymptomatic participant. Although the pooling test strategy might raise some concerns regarding the test performance (32), studies suggest that this testing modality could be implemented without compromising the sensitivity and specificity of the test (20, 33, 34). We consider that this technique should be implemented in a low-resource setting (for example, Mozambique) to upscale the test capacity.
Another limitation would be the study setting. We implemented the study in a referral hospital with comprehensive and specialised obstetric care. In addition, we included a population mainly from the urban region; thus, the sample might not represent the entire population. Therefore, the study finding should be interpreted with caution, limiting their generalizability.
Conversely, our study has some strengths. First, we conducted a prospective study. Prospectively collected data were used to implement an adequate measure and appropriate COVID-19 cases management at the hospital level, with early isolation of positive cases, rational use of protective equipment and reduction of COVID-19 hospital transmission. Second, to the best of our knowledge, this is one of the first works developed in low-resource countries in sub-Saharan Africa and might be used as a baseline for future studies. Third, our study highlighted the role of modifiable factors (alcohol consumption) in the risk of SARS-CoV-2 infection. Likewise, the evidence of a risk increase in adverse gestational outcomes can raise awareness for greater attention to this group of patients and guide the construction and implementation of public policies to deal with COVID-19 in the obstetric population at the local and regional level.