Malaria during pregnancy and newborns outcome in an unstable transmission area in Brazil: a population-based record linkage study

Background Malaria during pregnancy is one of the major causes of mortality in tropical regions, causing maternal anemia, intrauterine growth retardation, preterm birth, and low birth weight (LBW). The integration of the information systems is crucial to assess the dimension of gestational malaria in a wide and useful way, to improve decision making and maternal-child health. Methods and Findings An observational population-based study acquired information retrospectively from all live births that occurred between 2006 and 2014 in Cruzeiro do Sul (Acre, Brazil). Social and clinical data of the mother and newborn was extracted from the Information System of Live Births. Malaria episodes information was obtained from the Brazilian Epidemiological Surveillance Information System Malaria. A deterministic record linkage was performed to assess malaria impact on pregnancy. The studied population presented a malaria incidence of 8.9%, of which 63.9% infected by Plasmodium (P.) vivax. Reduction of newborns birth weight at term (small for gestational age (SGA) and LBW) has been found associated with P. vivax infection during pregnancy (SGA - OR 1.24, 95% CI 1.02-1.52, p=0.035; term LBW - OR 1.39, 95% CI 1.03-1.88, p=0.033). Additionally, P. falciparum infection during pregnancy has been found to be associated with preterm births (OR 1.54, 95% CI 1.09-2.18, p=0.016), which is related with late preterm births (OR 1.59, 95% CI 1.11-2.27, p=0.011). Conclusions Despite the decrease of malaria cases during the evaluated period, we present evidence of the deleterious effects of gestational malaria in a low transmission area in the Amazonian region. Regardless of Plasmodium species, malaria during pregnancy poses a risk for newborns birth weight reduction, highlighting the impact that P. vivax has on the fetus. Funding São Paulo Research Foundation - FAPESP/Brazil.


INTRODUCTION 48
Malaria is a severe and potentially fatal parasitic disease that constitutes a major public health issue, 49 being one of the greatest causes of mortality in tropical regions. Pregnant women are particularly 50 vulnerable to malaria infection and are estimated that 125 million women are at risk of malaria in 51 pregnancy each year 1 . Malaria can be devastating for both mother and fetus, leading up to 10,000 52 maternal and 75,000 to 200,000 child deaths each year 2 . Maternal malaria presents a significant 53 impact on the neonates, being the primary cause of abortion, stillbirth, premature delivery, fetal 54 death, low birth weight (LBW) and fetal/child development retardation in malaria-endemic 55 countries 2 . 56 LBW reflects an intra-uterine growth retardation (IUGR) and preterm delivery, which are 57 compelling indicators of infant morbidity 2-5 . LBW has been linked to infant mortality and poor 58 cognitive development, and the occurrence of non-communicable diseases later in life 5,6 . In fact, 59 LBW in newborns due to malaria is related with up to 100,000 infant deaths each year in endemic 60 countries 7,8 . These adverse birth outcomes have been extensively associated with P. falciparum 61 infection during pregnancy. In contrast to P. falciparum, the P. vivax burden in pregnancy is less 62 well described, and have been described as having less impact in the newborn 2,9 . Though, recent 63 studies have presented the two species as similar threats to the mother and fetus 10 . Despite the 64 efforts to reduce malaria the prevalence of these adverse birth outcomes remains high. 65 Therefore, it is crucial to have an efficient epidemiological surveillance of malaria during 66 pregnancy. The linkage of two or more health public surveillance record databases with shared 67 variables presents an important and effective strategy to plan preventive measures. Currently, most 68 of the malaria-endemic countries have malaria public surveillance record databases since it is 69 compulsory notification disease. This will contribute to the identification of epidemics and areas 70 most affected. Thus, allowing to direct and intensify the control and preventive measures to the 71 tests. Every p values were 2-sided at a significance level of <0.05. To assess the association 159 between malaria and birth weight reduction or prematurity, adjusted odds ratios (OR) with 95% 160 confidence intervals (CI) were estimated using a multivariate logistic regression approach. These 161 models included infections by malaria (yes / no), maternal age (≥ 18 years old / ≤ 17 years old), 162 gravidity (primigravida / multigravida), and years of formal education (≥ 4 years / ≤ 3 years) as 163 explanatory variables, and birth weight [≤ 10 th centile] (yes / no) or LBW (yes / no) as response 164 variables. The first category for each explanatory variable was considered as reference 20 . 165 166

Role of the funding source 167
The funders of this study played no part in the study design, data collection, data analysis, data 168 interpretation, or writing of the manuscript. The corresponding author had full access to all the data 169 in the study and had final responsibility for the decision to submit for publication.

Study Population and Baseline Characteristics 172
Between January 2006 and December 2014, 16,444 births occurred in Cruzeiro do Sul (Acre) with a 173 total of 3,021 malaria cases notified during pregnancy. After applying the exclusion criteria, 14,487 174 maternal-child pairs remained for further analysis (Fig 2). Table 1 shows maternal characteristics 175 according to infection status (detailed by year in the S1 Table). To highlight that: circa 35% of 176 women were primigravida; above 40% had at least 8 years of formal education (despite the high 177 proportion of no-schooling women); and more than 70% had a minimum of four antenatal visits 178 (Table 1). Nevertheless, it was possible to observe that there were no major differences between 179 non-infected and infected mothers. Malaria incidence in the studied population was 8.9%, with P. 180 vivax contributing to 63.9% of the cases (Fig 2). Time series of malaria cases in pregnant women 181 allowed to detect three epidemic peaks along the studied period, one in 2007 with more than 500 182 cases, and other two in 2010 and 2013 (Fig 3A and S2 Table). Interestingly, the significant 183 reduction of cases from 2007 to 2008 coincides with the introduction of artemisinin combined 184 therapy in Brazil 15 . Though, P. falciparum infections represented on average more than 30% of 185 cases reported during pregnancy, in the assessed years (S2 Table). 186 187         The analysis of the newborns birth weight across the nine years period, allowed to observe a 202 significant reduction in the mean weight of babies born from women that had malaria during 203 pregnancy ( Fig 3B, Table 2, and S3 Table). Newborns from P. falciparum-infected mothers 204 presented a more prominent difference of approximately 150 g (p<0.0001) when compared to 205 newborns from non-infected women (Table 2). Notably, the comparison of each group by year 206 evidenced that newborns from P. vivax-infected mothers showed higher weight reduction when 207 compared with non-infected (S3 Table). These differences can be explained by the higher 208 prevalence of newborns with LBW among P. vivax-infected women (term LBW: NI 4.8%, Pv 209 6.5%, p=0.031; all LBW: NI 6.8%, Pv 8.9%, p=0.020) ( Table 2 and S4 Table). Although this 210 prevalence occurred throughout the assessed years, it was more evident in 2006 and 2013 (S4 211   Table). 212 213 Median (

P. falciparum infection during pregnancy increases preterm births 252
The assembly of databases unveiled increased prematurity among babies born from P. falciparum-253 infected women during pregnancy (Table 2). Prematurity prevalence increased around 3% when 254 women were infected with P. falciparum, and the association was evidenced by multivariate logistic 255 regression analysis (OR 1.54, 95% CI 1.09-2.18, p=0.016), which corresponded with late preterm 256 births (OR 1.59, 95% CI 1.11-2.27, p=0.011) (Fig 6). Moreover, P. vivax infections were related to 257 very preterm births in women with malaria during pregnancy (OR 2.09, 95% CI 1.04-4.20, 258 p=0.039) (Fig 6). 259 Together, these results demonstrate that linkage of national record databases is a valuable research 260 tool, which disclosed adverse neonatal outcomes upon malaria infection during pregnancy in Brazil. Though, the prevalence is higher in relation to reports from Iquitos (6.6%) (Peru), and from other 284 Brazilian cities, such as Manaus (6.1%) and Coari (4.3%) in the Amazonas state, and Rio Branco 285 (1.4%) in Acre state [26][27][28][29] . The discrepancies may encompass differential study designs and 286 endemicity of studied areas. 287 Prematurity is one of the adverse effects commonly observed in malaria during pregnancy 6,30,31 . 288 Usually, it correlates with infections occurring during the third trimester of pregnancy and 289 contributes to increasing the number of newborns with LBW, which is more likely to be observed in 290 low transmission areas 2,32 . In fact, our data show that P. falciparum infections during pregnancy are 291 responsible for a high proportion of preterm births, mainly late preterm births (≥32 and <37 weeks 292 of gestation). However, it was not possible to correlate the time of infection with the gestational 293

trimester. 294
Newborns reduced weight at birth either classified as LBW or SGA, is an important predictive 295 marker of neonatal and child survival, and can result from two basic factors: intrauterine growth 296 restriction and preterm births 33,31 . In gestational malaria, birth weight reduction is the main adverse 297 outcome observed in studies involving P. falciparum infections 2,30,34,35 . In our observations, 298 malaria infection during pregnancy represents a critical morbidity that impacts newborns' weight. 299 The records show that malaria in pregnant women increases the number of babies born at term with 300 The reduction of newborns birth weight is multifactorial, and it can be related to social-economic, 311 environmental, nutritional, and clinic factors during pregnancy. However, in this study, it was not 312 possible to assess other risk factors, once these variables were absent in the databases used. Of note, 313 it is important to highlight that it is impossible to compare this study with other carried out in 314 Africa. There, P. falciparum infections are predominant and, in general, the health systems that 315 diagnose and treat malaria have several limitations, summed up with the high rate of co-infection 316 with other diseases, such as HIV and tuberculosis. The Brazilian Amazonian region has a health 317 care system with effective strategies to control, diagnose, and treat malaria, despite being a low 318 transmission area with predominance of P. vivax infections. These characteristics make our findings 319 even more interesting, as we observed a substantial impact of infection during pregnancy in 320 newborns. 321 In Brazil, malaria is a mandatory notification disease, and SIVEP-Malaria is essential to plan health 322 interventions that enable effective control and preventive strategies to eradicate the disease. For 323 pregnant women, the early diagnosis is essential to prevent adverse outcomes. In 2014, it was 324 We thank Health Surveillance Secretariat of Acre for authorizing the data collection. Also, we thank 345 the Municipal Health Secretariat of Cruzeiro do Sul, which promptly welcome us and provided us 346 access to the SINASC database, and to the Brazilian Epidemiological Surveillance/Administration 347 of Endemics, which authorized the assess to SIVEP-Malaria information.    1 S1