Syphilis in during pregnancy: association of maternal and perinatal characteristics in a region of southern Brazil 1

ABSTRACT Objective: To analyze the prevalence of syphilis in during pregnancy and its association with socioeconomic characteristics, reproductive history, prenatal and labor care, and newborn characteristics. Method: A retrospective, cross-sectional study based on gestational and congenital syphilis reports. A (records) linkage was performed in the Brazilian databases: “Information System for Notifiable Diseases” (Sistema de Informação de Agravos de Notificação - SINAN); “Live Births Information System” (Sistema de Informação sobre Nascidos Vivos - SINASC); and “Mortality Information System” (Sistema de Informação sobre Mortalidade - SIM). Results: The prevalence of gestational syphilis was 0.57%. The following associations of syphilis in pregnancy were found: non-white skin color/ethnicity (PR=4.6, CI=3.62-5.76); low educational level (PR=15.4; CI=12.60-18.86); and absence of prenatal care (PR=7.4, CI=3.68-14.9). The perinatal outcomes associated with gestational syphilis were prematurity (PR=1.6 CI=1.17-2.21) and low birth weight (PR=1.6; CI=1.14-2.28). Two deaths from congenital syphilis, one death from another cause and five stillbirths were reported. Conclusion: The results signify a long way until reaching the World Health Organization’s goal of eradicating congenital syphilis.


Method
SINAN was used to access the total number of syphilis reports in gestation and congenital syphilis for studied the period and region. Sinasc was used to obtain data on the obstetric history of the mother in cases of live births, in addition to newborn data. Lastly, the SIM database was used to obtain data regarding the obstetric history of mothers in cases of abortion and stillbirths, in addition to records of neonatal death due to congenital syphilis.
A linkage of the SINAN-gestational syphilis, Sinasc and SIM databases was carried out using the variables: "patient's name", "date of birth and/or age" in the SINANgestational syphilis; and "mother's name", "maternal date of birth and/or age" in the Sinasc database; and the variable "mother's name" in the SIM database. After unification of the databases, it was observed that 36 pregnant women who had been reported as having syphilis during pregnancy had no records of their babies in the Sinasc or SIM databases, and were excluded from the analysis.
After performing the (records) linkage between syphilis in pregnancy and congenital syphilis in the databases, it was observed that 14 newborns did not have records of their respective mothers' reports, therefore they were also excluded from the analysis.
Another 15 cases were subsequently excluded for not having their respective records included in the Sinasc or in the SIM databases, therefore resulting in 147 cases of congenital syphilis included in the analysis.
A ratio of the total number of reported cases of syphilis during pregnancy (306) divided by the number of pregnancies in the period multiplied by 100 was used to estimate syphilis prevalence in gestation (number of existing cases of the disease in the population). The Padovani C, Oliveira RR, Pelloso SM.
number of pregnancies was obtained by the sum of live births, abortions and stillbirths recorded in the period, while the number of reported cases divided by the number of live births multiplied by 1,000 was used for the detection rate of syphilis in pregnant women (annual incidence of the disease).   the majority of notified cases classified as "primary" syphilis (61.11%) ( Table 2).
The treatment of pregnant women with syphilis was considered inappropriate or was not performed in 53.70% of the cases. There was no treatment for the partner of the pregnant woman in 64.07% of the cases, and the most reported reasons were: the pregnant woman lost contact with the partner, the partner's serology was not reactive, the partner was invited but he did not attend, among other reasons ( Table 2).

Discussion
To the best of our knowledge, this is the first study conducted in southern Brazil that investigated the results of syphilis during pregnancy associated with maternal and perinatal factors. The present study found a detection rate of syphilis during gestation of 12.79 cases/thousand live births, which is similar data to that found in the Southeast region (12.6), and above the national rate (11.2). We also found an association of non-white skin color/ethnicity, low educational level, and companion absence during prenatal care with syphilis during pregnancy, as well as the occurrence of prematurity and low birth weight associated with gestational syphilis.
The incidence rate of congenital syphilis in the studied region for the year 2015 was 9.67 cases/ thousand live births; higher than the national incidence in the same year, which was 6.5 cases per thousand live births, and far from the stipulated target of 0 Transmitted Diseases (STDs) (9) .
Characteristics such as non-white skin color/ ethnicity, low educational level and absence of paid occupation are variables that were statistically associated with gestational syphilis, and are similar to other studies* (5,8,(10)(11) . This is often the profile of individuals with a less favorable socioeconomic condition and with less access to quality healthcare. However, it cannot be said that syphilis is exclusively a risk condition for the most deprived populations; on the contrary, anyone can acquire the infection regardless of social or economic condition, however the risk is higher in more vulnerable populations (12) .
Multiparous women with a history of fetal loss and without prenatal care or with a low number of prenatal visits were also statistically associated with the occurrence of syphilis during gestation. In Brazil, prenatal coverage is greater than 95% (13-15) . However, it is known that high prenatal coverage rates do not necessarily mean quality and adequacy of care. There are several factors that produce adequate prenatal care, such as gestational age at the beginning of prenatal care, number of consultations, and the performance of routine examinations, among others (16) .
In addition, there are some pregnant women without any prenatal follow-up or prenatal consultations; these women constitute a socially vulnerable population and manifest a higher prevalence of syphilis during pregnancy (13-15) .
Regarding the type of delivery, syphilis was more prevalent in women who had their children through vaginal delivery. According to some authors, this data may be related to the socioeconomic condition (16) . In Brazil, the highest cesarean rates are historically related to factors such as more privileged socioeconomic situation, having white skin color/ethnicity, having a higher educational level and access to private health services, while vaginal delivery is still more common in public health services in women of lower socioeconomic power, and with lower education levels (17)(18) .
With regard to the early diagnosis of syphilis in pregnant women, the majority of women were diagnosed during prenatal care. Some studies show that outcomes of non-identification and (lack of) early treatment of infection during pregnancy are severe for the infant, and these outcomes depend on the stage of maternal In this study, it was observed that the partner was not treated and the main reasons were absence of contact with the pregnant woman, unreactive serology and treatment refusal. Other studies also address the importance of treating the partner(s) in curing gestational syphilis and preventing vertical transmission (5,(7)(8) , thus not only indicating the importance of health education for pregnant women, but also for the sexual partners.
It should be noted that this study has some limitations such as the use of secondary data, since they are conditioned to the quality of the records, in addition to allowing for estimating how much the frequency of underreporting can distort the results, which can even lead to regional disparities. However, despite their limitations, the databases used are considered reliable, of good quality and with reliable information. In addition, the linkage of different databases enabled a more comprehensive analysis of the reported syphilis cases during pregnancy.

Conclusion
The results of this study show that there is still much progress to be made towards the WHO goal of eliminating congenital syphilis as a public health problem.
The prevalence of gestational syphilis was 0.57%, and the analyzes indicated several variables associated with its occurrence such as age, non-white skin color/ ethnicity, low education level and absence of prenatal follow-up. Prematurity and low birth weight were associated with gestational syphilis and were related to perinatal outcomes such as the occurrence of two deaths by congenital syphilis and five cases of stillbirth among the newborns of mothers with syphilis during pregnancy.
In order to reduce the prevalence of syphilis in pregnancy and congenital syphilis, it is essential that health professionals and the community become aware of the importance of early diagnosis and the effective treatment of women and their partners. The multiprofessional team is responsible for screening pregnant women in prenatal consultations, actions to raise awareness about the risks of unsafe sexual practices and the importance of self-care, especially among the most vulnerable populations.