Prevalência de nascimentos gemelares em Pelotas, Rio Grande do Sul, Brasil

Twin Peaks: A spatial and temporal study of twinning rates in Brazil

Twin births are an important public health issue due to health complications for both mother and children. While it is known that contemporary factors have drastically changed the epidemiology of twins in certain developed countries, in Brazil, relevant data are still scarce. Thus, we carried out a population-based study of live births in spatial and temporal dimensions using data from Brazil's Live Birth Information System, which covers the entire country. Over 41 million births registered between 2001 and 2014 were classified as singleton, twin or multiple. Twinning rates (TR) averaged 9.41 per 1,000 for the study period and a first-order autoregressive model of time-series analysis revealed a global upward trend over time; however, there were important regional differences. In fact, a Cluster and Outlier Analysis (Anselin Local Moran's I) was performed and identified clusters of high TR in an area stretching from the south of Brazil's Northeast Region to the South Region (Global Moran Index = 0.062, P < 0.001). Spearman's correlation coefficient and a Wilcoxon matched pairs test revealed a positive association between Human Development Index (HDI) and TRs in different scenarios, suggesting that the HDI might be an important indicator of childbearing age and assisted reproduction techniques in Brazil. Furthermore, there was a sharp increase of 26.42% in TR in women aged 45 and over during study period. The upward temporal trend in TRs is in line with recent observations from other countries, while the spatial analysis has revealed two very different realities within the same country. Our approach to TR using HDI as a proxy for underlying socioeconomic changes can be applied to other developing countries with regional inequalities resembling those found in Brazil.

Twinning and Multiple Birth Rates According to Maternal Age in the City of São Paulo, Brazil: 2003–2014

The present study investigates the twinning rates in the city of São Paulo, Brazil, during the years 2003–2014. The data were drawn from the Brazilian Health Department database of Sistema de Informações de Nascidos Vivos de São Paulo—SINASC (Live Births Information System of São Paulo). In general, more information is available on the incidence of twinning in developed countries than in developing ones. A total of 24,589 twin deliveries and 736 multiple deliveries were registered in 140 hospitals of São Paulo out of a total of 2,056,016 deliveries during the studied time period. The overall average rates of singleton, twin, and multiple births per 1,000 maternities (‰) were 987.43, 11.96 (dizygotic (DZ) rate was 7.15 and monozygotic (MZ) 4.42), and 0.36, respectively. We further regressed maternal age and historical time period on percentage of singleton, twin, and multiple birth rates. Our results indicated that maternal age strongly positively predicted twin and multiple birth rates, and negatively predicted singleton birth rates. The historical time period also positively, although weakly, predicted twin birth rates, and had no effect on singleton or multiple birth rates. Further, after applying Weinberg's differential method, we computed regressions separately for the estimated frequencies of DZ and MZ twin rates. DZ twinning was strongly positively predicted by maternal age and, to a smaller degree, by time period, while MZ twinning increased marginally only with higher maternal age. Factors such as increasing body mass index or air pollution can lead to the slight historical increase in DZ twinning rates. Importantly, consistent with previous cross-cultural and historical research, our results support the existence of an age-dependent physiological mechanism that leads to a strong increase in twinning and multiple births, but not singleton births, among mothers of higher age categories. From the ultimate perspective, twinning and multiple births in later age can lead to higher individual reproductive success near the end of the reproductive career of the mother.

Análise espacial dos aglomerados de nascimentos ocorridos em hospitais SUS e não SUS do município de São Paulo, Brasil

O objetivo deste estudo é avaliar a distribuição espacial de nascidos vivos (NV) do município de São Paulo (MSP), verificar se há dependência espacial, identificar possíveis diferenças no perfil dos nascimentos e avaliar as distâncias percorridas entre os domicílios e os hospitais do parto. Foram estudados os NV ocorridos em hospitais de alta complexidade, quatro SUS e quatro da rede não SUS no MSP em 2008. Foram georreferenciados 46.190 NV: 48,8% em hospitais SUS e 51,2% não SUS, estes representaram 27,9% do total de NV do MSP. Os NV de hospitais SUS formaram dois aglomerados com elevada proporção de domicílios com renda de 1/2 a 2SM, concentração de favelas e altas taxas de natalidade. Os NV de hospitais não SUS formaram um aglomerado na região central do MSP, onde há elevada proporção de domicílios com renda > 10 SM e baixa natalidade. Foram encontradas diferenças estaticamente significantes das características maternas, da gestação e do parto entre os NV de hospitais SUS e não SUS e da frequência de gemelaridade. Não houve diferença na prevalência de baixo peso e pré-termo. Os resultados mostraram existir diferenciais no perfil dos aglomerados de NV, que refletem as desigualdades das condições de vida do MSP.