-->PONE-D-24-43130-->-->Fertility rate among adolescents in Brazil in the period 2012-2021: effects of human development, primary care coverage and the COVID-19 pandemic.-->-->PLOS ONE

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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-->2. Has the statistical analysis been performed appropriately and rigorously? -->

Reviewer #1: Yes

Reviewer #2: I Don't Know

Reviewer #3: No

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

Reviewer #3: Yes

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-->5. Review Comments to the Author

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Reviewer #1: Meus comentário estão em anexo. De modo geral artigo é muito bem escrito e traz dados inovadores no estudo da fecundidade de 10 a 19 anos quando para além da análise temporal faz a inserção do período pandêmico e inova no uso do método. A análise espacial e seus resultados são bem interessantes. Meus comentários são a fim de esclarecer alguns aspectos que acredito serem relevantes.

Reviewer #2: This paper addresses an crucial public health matter for brazil and other nations of poor or medium development. Analytical procedures advances the scientific literature available in the field.

Report is quite well described and addresses the main results.

As for minor revisions I suggest but not condition changes in the title, from:

Fertility rate among adolescents in Brazil in the period 2012-2021: effects of human development, primary care coverage and the COVID-19 pandemic.

to: Effects of human development, primary care coverage and the COVID-19 pandemic on the fertility rate among adolescents in Brazil in the period 2012-2021

Other considerations follow bellow

Introduction:

Line 49 --> reduction repeat 2x, please rephrase

Lines 59-60 --> And/Or is not well applied, please adjust

Lines 77-78 are quite not conected with the overal rationale presented, I advise authors to better locate the importance of this argument in the context of their rationale. Restate.

Methods:

In this section, the trend analysis does not show in abstract and in the type of study in the 1st paragraph. This adjustment is necessary.

Página 13, linhas 27-28 this information only appears at the end of the Methods section, and its complementary to the one in the introdcution which was quite disconected to the rationale. Please restate the comparison made with de pre and pandemic years justifying this analytical procedure in both sections.

It is not quite clear in the explanation, why for the spacial analysis only 2 periods were selected, excluding all data form 2012 to 2017. Wouldn´t it be more appropriate to have a period as well in the beggining of the series? Why did the authors made this decision?

Moreover, spacial analysis details requires more thorough explanation and references.

Results:

Figure 2 and Figure 3 have diferences in the purple (high FR) gradient and this should be better explained in the text.

Text with results of Figure 4, page 20 lines 42-60 are not in a very well comprehensive and usual format. Authors should review this presentation.

Discussion:

Page 22 lines 35-37 mention an interaction analysis that was not mentioned in Methods analytical procedures.

Authors must include that dispite of the forecasts isolation during the pandemic might have had an effect on the adolescent opportunities of sexual intercourse as described in previous studies, although might have increased sexual violence.

Authors were very discrete in discussing the the observed benefits of increasing

PCP coverage in reducing the fertility rate, common to both age groups and this need more consideration, since it is a differencial.

Other issue is the political scenario and program change towards sexual and reproductive health of the country in face of these results. Aren´t they controversial?

Authors would advance if in this section they compare Brazil´s adolesct FR reduction to other countries, since we are following behing. PHC is up since 1994, why the effect is just in the last decade?

Reviewer #3: Adolescent Pregnancy and Public Health

Adolescent pregnancy is a significant public health issue, as complications during pregnancy and childbirth represent the leading cause of mortality among girls aged 15 to 19 years. Furthermore, its social impact is substantial, frequently leading to school dropouts. Given that its incidence is higher among the most socioeconomically vulnerable groups, adolescent pregnancy contributes to the perpetuation of poverty.

Socioeconomic and cultural factors strongly influence reproductive behavior during adolescence. Brazil has experienced a rapid decline in fertility rates; however, significant regional and socioeconomic disparities persist. These variations and differences in access to primary healthcare and education make the country a valuable case for analyzing this phenomenon. I acknowledge the relevance of the topic addressed in the article under review. However, several methodological issues require further discussion.

Text Revision and Introduction

One key aspect that deserves attention is the need for a text revision, particularly in the introduction. For instance, on page 3, line 58, the authors state: "Despite advances, with a drop in the fertility rate in some Latin American countries, inequities persist." I believe the word "some" could be removed, as all countries in the region have experienced a decline in fertility rates.

Methodology

An important issue that requires attention is the population data used to calculate fertility rates. The authors did not use the most recent population estimates (http://tabnet.datasus.gov.br/cgi/deftohtm.exe?ibge/cnv/popsvs2024br.def). Since many analyses were conducted at the municipal level, population changes may have a non-negligible impact on fertility rate calculations.

The first step of the analysis consists of assessing the trend in adolescent fertility rates for the 10–14 and 15–19 age groups from 2012 to 2021 by federative unit. To do so, the authors applied the nonparametric Mann-Kendall test to verify the existence of a monotonic increasing or decreasing trend over time. The approach is straightforward and clear.

In the spatial analysis, both age groups were again analyzed separately, but the period was restricted to 2018–2021. The authors justify this decision by the need for better comparability, ensuring that the pre-COVID-19 period (2018–2019) has the same duration as the pandemic period (2020–2021).

For this analysis, the authors used different clustering methods (k-means, k-medoids, Ward’s method, single linkage, and average linkage). They selected the best approach based on performance metrics (Davies-Bouldin, Dunn, Silhouette, and the Calinski-Harabasz index). However, the results of these metrics were not presented, and the authors merely stated that k-means with three groups were the chosen method. I consider these results to be included and discussed in the article.

Additionally, it would be essential to justify the choice of these methods, given that they do not account for spatial correlation. Spatial correlation is a relevant factor in adolescent fertility as it involves cultural aspects associated with the place of residence.

Another questionable aspect is Dunn’s multiple comparison test, given that k-means inherently aims to minimize within-cluster variance. The necessity of this additional test is not evident and should be better justified in the text.

Main Analysis

My main criticism of the article relates to the core analysis, which investigates the association between adolescent fertility rates (ages 10–19) and primary healthcare coverage at the municipal level. Although the authors have made their data and code available, ensuring transparency in their analyses, this does not exempt them from explicitly stating in the text which dependent variable was modeled.

The square root of fertility rates was used as the response variable, possibly to approximate a normal distribution. However, it is unclear why this transformation was applied instead of modeling the fertility rate directly using a Poisson or Negative Binomial model, which would be more appropriate for dealing with count data. The decision to use the square root transformation should be justified, especially considering that other approaches are more suitable for counting data.

Furthermore, the authors’ decision to consider the year as the level-2 unit in the multilevel model raises concerns. In this structure, municipalities are nested within years of pregnancy occurrence, which does not seem to reflect the data's hierarchical structure adequately.

I think the most appropriate approach would be to consider year level 1 and municipality level 2 since fertility rates within the same municipality tend to be correlated over time. Even if the study’s primary interest is comparing pandemic and pre-pandemic years, it isn't easy to justify the assumption that fertility rates within a given municipality are independent over time. This methodological decision should be revised or, at the very least, better justified in the text.

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Reviewer #1: No

Reviewer #2: No

Reviewer #3: No

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Effects of human development, primary care coverage and the COVID-19 pandemic on the fertility rate among adolescents in Brazil in the period 2012-2021

PONE-D-24-43130R1

Dear Dr. Domingues,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

In relation to your clarification of software licensing "We would like to inform you that the maps in Figures 2 and 3 were generated by us using the R software, specifically with the geobr and ggplot2 packages. The geobr package provides official spatial data from Brazil, obtained directly from governmental sources such as the IBGE, which are in the public domain and do not have copyright restrictions for use in research and publications. The geobr package itself is licensed under the MIT License. The ggplot2 package, used for visualization and customization of these data, is also licensed under the MIT License. Therefore, the underlying map image is based on public data from the Brazilian government, accessed through a widely used and openly licensed R package, and carries no copyright restrictions for scientific publication. We included this explanation in the methods section and in the footnote of figures 2 and 3.", which was quite thorough in my view, I must inform you that the Editorial Office of Plos One will add to this decision letter requirements as to its understanding of use of the R Package.

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Claudia Garcia Serpa Osorio-de-Castro, Ph.D

Academic Editor

PLOS ONE

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Reviewers' comments:

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Reviewer #1: All comments have been addressed

Reviewer #3: All comments have been addressed

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-->2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented. -->

Reviewer #1: Yes

Reviewer #3: Yes

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-->3. Has the statistical analysis been performed appropriately and rigorously? -->

Reviewer #1: Yes

Reviewer #3: Yes

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-->4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.-->

Reviewer #1: Yes

Reviewer #3: Yes

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-->5. Is the manuscript presented in an intelligible fashion and written in standard English?

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Reviewer #3: Yes

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Reviewer #1: O artigo já passou por três revisões, as quais atentaram para a maior parte das minhas observações.

Faço um único comentário: a fecundidade adolescente tipicamente diz respeito ao grupo de 15 a 19 anos, a fecundidade do grupo de 10 a 14 anos, apesar de também ser definida como fecundidade adolescente, não pode ser analisada sem uma discussão importante sobre direito. Temos que deixar claro que, na verdade, estamos falando de crianças, em que os dados apontam que, na maioria das vezes, a gravidez nessa idade não é intencional, e frequentemente também está relacionada a situações de abusos e violência sexual. Acho que os autores não podem trabalhar com esse dado da mesma forma que o do grupo de adolescentes de 15 a 19 anos. Como para esse grupo o sistema de saúde faria diferença? Como o sistema de saúde pode proteger essas crianças? E o sistema educacional? Em algum momento, esse tipo de reflexão precisa entrar no texto.

Ainda vejo problema na estima da fecundidade adolescente em nível municipal, não se trata apenas de uma questão de ter zero em um determinado ano, mas da variabilidade do evento ao longo do período. Existem metodologias específicas em estudos demográficos que trabalham melhor esse dado a partir de modelagens estatística.

Reviewer #3: The authors made all the necessary changes and provided clear explanations. The article should be accepted for publication, as it addresses a highly relevant topic and employs an appropriate methodology.

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Reviewer #1: No

Reviewer #3: No

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