We thank Tang et al. ¹1. Tang Mi, Cai J, Liang H. Letter to the Editors on the article by Melo & Araújo. Cad Saúde Pública 2021; 37:e00159721. for the comments and for honoring our study entitled COVID-19 Infection in Pregnant Women, Preterm Delivery, Birth Weight, and Vertical Transmission: A Systematic Review and Meta-analysis²2. Melo GC, Araújo KCGM. COVID-19 infection in pregnant women, preterm delivery, birth weight, and vertical transmission: a systematic review and meta-analysis. Cad Saúde Pública 2020; 36:e00087320.. We reinforce the limitations of our review, especially due to being constructed based on initial studies on the subject, while recognizing its informative significance in the face of the emergence of the COVID-19 pandemic.

In view of this aspect, we clarify our awareness that duplicate studies or those with overlap of participants should not be included in systematic reviews and, above all, in meta-analyses. For this reason, specially, Table 1 of our review (presenting only the studies included in the meta-analysis) shows information about the place of recruitment of the included pregnant women.

Regarding the other studies presented in Table 2 of the systematic review, we were careful to include the recruitment period of each research to reduce the possibility of including duplicate studies. The characteristics of the participants included in the studies were also observed and described in detail, mainly due to the studies that were conducted in the same institutions in China but that included neonates or women with a certain route of delivery (vaginal or cesarean).

However, we recognize that the references commented in the letter ¹ (9 and 30) have samples (n = 7 and n = 9, respectively) recruited in overlapping periods, which was a mistake on the part of the authors. Thus, the study of reference 30 ³3. Yang P, Wang X, Liu P, Wei C, He B, Zheng J, et al. Clinical characteristics and risk assessment of newborns born to mothers with COVID-19. J Clin Virol 2020; 127:104356. should be disregarded from the qualitative review framework. Similarly, references 26 and 27 ⁴4. Liu W, Wang Q, Zhang Q, Chen L, Chen J, Zhang B, et al. Coronavirus disease 2019 (COVID-19) during pregnancy: a case series. Preprints 2020; 25 feb. https://www.preprints.org/manuscript/202002.0373/v1.
https://www.preprints.org/manuscript/202... ^,55. Liu W, Wang Li W, Zhou ZX, Liu SY, Rong ZH. Clinical characteristics of 19 neonates born to mothers with COVID-19. Front Med 2020; 14:193-8. have overlapping samples (n = 3 and n = 19, respectively). This first (reference 26) should be disregarded from the qualitative review. We also recognize that the references 9 and 35 ⁶6. Chen H, Guo J, Wang C, Luo F, Yu X, Zhang W, et al. Clinical characteristics and intrauterine vertical transmission potential of COVID-19 infection in nine pregnant women: a retrospective review of medical records. Lancet 2020; 395:809-15.^,77. Chen S, Liao E, Cao D, Gao Y, Sun G, Shao Y. Clinical analysis of pregnant women with 2019 novel coronavirus pneumonia. J Med Virol 2020; 92:1556-61. are misplaced in the same table.

Finally, note that these mistakes do not influence the qualitative evaluation of the evidence described, nor the quantitative results of the study, since the references were not included in the meta-analysis.

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