Sociodemographic, behavioral, obstetric, and healthcare factors associated with low weight at birth: a case-control study

ABSTRACT BACKGROUND: Understanding social determinants is crucial for implementing preventive strategies, especially for low birth weight (LBW)—a public health issue that severely increases the risk of morbimortality in children. OBJECTIVE: This study aimed to identify the factors associated with LBW among newborns, assisted by the Brazilian Unified Health System. DESIGN AND SETTING: It analyzed data from newborns and their mothers. The sample was selected by convenience from users of the public health system in Francisco Beltrão (Paraná, Brazil). METHODS: Cases (n = 26) were babies weighing ≤ 2,500 g and controls (n = 52) > 2,500 g. All babies were assessed and paired by sex and date of birth in a 1:2 proportion. Statistical power was computed a posteriori, revealing a power of 87% (α = 0.05). RESULTS: Strong and significant differences were found in the bivariate analysis, in which the number of current smokers or those who quit during pregnancy was higher among mothers of babies with LBW. Moreover, the gestational weeks were lower among these cases. Logistic regression models indicated that the gestational week (odds ratio [OR] = 0.17, 95% confidence interval [CI]:0.05-0.54) and fathers' educational level (high school or above; OR = 0.22, 95% CI:0.06-0.99) were related to lower chances of low birth weight. CONCLUSIONS: Our findings confirm previous investigations on LBW's multi-causality, showing that the gestational week could reduce up to 82% chances of a baby being born with ≤ 2,500 g. Its association with paternal education underlines the importance of comprehensive policies to protect newborns.

Meiotic behavior during microsporogenesis of Alchornea triplinervia (Sprengel) Müller Argoviensis / Comportamento meiótico durante a microsporogênese de Alchornea triplinervia (Sprengel) Müller Argoviensis

The Alchornea triplinervia specie belongs to the Euphorbiaceae family, one of the main families of the Brazilian flora. In order to contribute to a better understanding of the specie, a counting of chromosome number and the microsporogenesis analysis of A. triplinervia were done. The inflorescences were collected in the municipalities of Paranavaí and Diamante do Norte, State of Paraná, Brazil, and the slides were prepared by squashing technique and staining with 1% acetic carmine. The analysis were performed using an optical microscope and showed a chromosome number for the specie equal to 2n=8x=72. Irregularities in the chromosome segregation process were the main meiotic abnormalities, presenting typical polyploid behavior. Other irregularities were observed; however, at low frequency without compromising the pollen grain formation of the analyzed plants.

A espécie Alchornea triplinervia pertence à família Euphorbiaceae, uma das principais famílias da flora brasileira. Visando a contribuir para um melhor entendimento da espécie, foi realizada a contagem do número de cromossomos e a análise da microsporogênese de A. triplinervia. As Inflorescências foram coletadas nos Municípios de Paranavaí e Diamante do Norte, no Estado do Paraná, Brasil, sendo as lâminas preparadas pela técnica de esmagamento e coradas com carmim acético 1%. As análises foram realizadas ao microscópio óptico, revelando um número cromossômico para a espécie igual a 2n=8x=72. Irregularidades no processo de segregação dos cromossomos foram as principais anormalidades meióticas, mostrando comportamento típico de poliploides. Outras irregularidades foram observadas, porém, em baixa frequência, não comprometendo a formação dos grãos de pólen das plantas analisadas.

Chromosome stickiness during meiotic behavior analysis of Passiflora serrato-digitata L. (PassifloraCEAE) / Aderência cromossômica durante a análise do comportamento meiótico de Passiflora serrato-digitata L (PassifloraCEAE)

Almost 90 percent of species of the genus Passiflora are native to the American continent, with high commercial value due to the fact that some species are used for human food while others have ornamental and medical qualities. Passiflora serrato-digitata is one of the species that integrates the Paraná Agronomic Institute germoplasm bank at its experimental base in Londrina, PR, Brazil. Collected flower buds were fixed in ethanol/acetic acid (3:1 v/v) for 24h, transferred to 70 percent alcohol and stored under refrigeration. Slides were prepared by the squashing technique and stained with 1.0 percent propionic carmine; they were analyzed under an optic microscope. Irregularities in the chromosome segregation process of P. serrato-digitata have been verified by meiotic behavior analysis. These comprised precocious migration to poles in metaphase I and II, non-oriented chromosomes in metaphase plate in metaphase I and II, laggard chromosomes in anaphase I and II towards the formation of micronucleus in telophase I and II, and microspores in tetrads. Chromosome stickiness was another irregularity reported in the Passiflora genus for the first time. These irregularities which also contributed to the formation of monads, dyads and triads, resulted in normal imbalanced 2n and 4n microspores. According to the observed Meiotic Index of 71.83 percent, this species is not meiotically stable.

Cerca de 90 por cento das espécies do gênero Passiflora são nativas das Américas, sendo que aproximadamente 200 espécies são nativas do Brasil. Possuem grande importância comercial, pois algumas espécies são utilizadas na alimentação humana, outras apresentam propriedades medicinais e ornamentais. A espécie Passiflora serrato-digitata faz parte do banco de germoplasma do Instituto Agronômico do Paraná - IAPAR, estação experimental de Londrina, PR. Botões florais colhidos foram fixados em etanol/ácido acético (3:1 v/v) por 24 horas, transferidos para álcool a 70 por cento e acondicionado sob refrigeração. As lâminas foram preparadas pela técnica de esmagamento e coradas com carmim propiônico a 1,0 por cento e observadas ao microscópio óptico. Por meio da análise do comportamento meiótico, foram verificadas irregularidades no processo de segregação dos cromossomos de P. serrato-digitata, tais como migração precoce para os pólos em metáfase I e II, cromossomos não orientados na placa equatorial em metáfase I e II, cromossomos retardatários em anáfase I e II, levando a formação de micronúcleo em telófases I e II e micrósporos em tétrades. Outra irregularidade observada foi aderência cromossômica, relatada pela primeira vez no gênero Passiflora, que também pode ter contribuído para a formação de mônades, díades, tríades, as quais foram observadas, resultando em micrósporos normais, desbalanceados, 2n e 4n. De acordo com o Índice Meiótico de 71,83 por cento observado, essa espécie pode ser classificada como não estável meioticamente.

Comportamento meiótico durante a microsporogênese em espécies da família meliaceae / Comportamiento meiótica durante la microsporogénesis en especies de la familia meliaceae / Meiotic behavior during microsporogenesis of some species of meliaceae family

A família Meliaceae inclui espécies de grande interesse agronômico, ecológico, econômico e ornamental de alto potencial madeireiro no mundo. No Brasil ocorrem cerca de seis gêneros e 100 espécies. Considerando a falta de estudos citológicos para esse grupo, este trabalho descreve o comportamento meiótico durante a microsporogênese de seis espécies (Trichilia pallida, Trichilia elegans, Trichilia catigua, Cedrela fissilis, Cabralea canjerana, Guarea guidonea) da família Meliaceae, representando quatro dos seis gêneros que estão presentes no Brasil. Inflorescências foram coletadas e fixadas em etanol/ácido acético (3:1 v/v) por 24 horas, transferidos para álcool a 70%, e acondicionadas sob refrigeração. As lâminas foram preparadas pela técnica de esmagamento, coradas com carmim acético a 1%. A análise citogenética revelou poucas irregularidades meióticas, sendo estas relacionadas a segregação dos cromossomos, fusos irregulares e conexão citoplasmática. Como consequência da segregação irregular dos cromossomos na meiose I e II e da organização irregular dos fusos na meiose II, o padrão de citocinese também foi irregular originando tétrades com micrócitos e tríades, resultando em micrósporos desbalanceados e de núcleo restituído (2n).

The Meliaceae family includes the most important species with great agronomic, ecological, economic and ornamental value and high timber potential in the world. In Brazil, approximately six genera and 100 species are found. Considering the lack of cytological studies for its genera, the present study describes the meiotic behavior during microsporogenesis of six species of the Meliaceae family, representing four of the six genera that are present in Brazil; these species are: Trichilia pallida, Trichilia elegans, Trichilia catigua, Cedrela fissilis, Cabralea canjerana, Guarea guidonea. Inflorescences were collected and fixed in ethanol/acetic acid (3:1 v/v) for 24 hours, transferred to alcohol at 70%, and stored under refrigeration. The slides were prepared by squashing, and stained with acetic carmine 1% and observed under optical microscopy. Cytogenetic analysis revealed few meiotic irregularities, which are related to segregation of chromosome spindles and irregular cytoplasmic connection. As a result of irregular segregation of chromosomes during meiosis I and II and the irregular organization of the spindles in meiosis II, the pattern of cytokinesis was also irregular resulting in microcytic tetrads and triads, unbalanced microspores and restored nuclei (2n).

La familia Meliaceae incluye especies de gran interés agronómico, ecológico, económico y ornamental de alto potencial maderero en el mundo. En Brasil ocurren cerca de seis géneros y 100 especies. Considerando la falta de estudios citológicos para ese grupo, este trabajo describe el comportamiento meiótica durante la microsporogénesis de seis especies (Trichilia pallida, Trichilia elegans, Trichilia catigua, Cedrela fissilis, Cabralea canjerana, Guarea guidonea) de la familia Meliaceae, representando cuatro de los seis géneros que están presentes en Brasil. Inflorescencias fueran colectadas y fijadas en etanol/ácido acético (3:1 v/v) por 24 horas, transferidos para alcohol a 70%, y acondicionadas bajo refrigeración. Las láminas fueron preparadas por la técnica de aplastamiento, coloradas con carmín acético a 1%. El análisis citogenética reveló pocas irregularidades meióticas, siendo éstas relacionadas a la segregación de los cromosomas, fusos irregulares y conexión citoplasmática. Como consecuencia de segregación irregular de cromosomas en la meiosis I y II y de la organización irregular de los fusos en la meiosis II, el estándar de citocinesis también fue irregular originando tétradas con micrófitos y tríades, resultando en micros poros desbalanceados y de núcleo restituido (2n).

Abnormal behavior of spindle during microsporogenesis of passiflora (passifloraceae) / Comportamento anormal de fuso durante a microsporogênese de passiflora (passifloraceae)ien

Passiflora genus, Passifloraceae family, has more than 500 species and 120 of them are native species of Brazil. All species produce fruits that are used as food, medicine and decoration. Floral buttons of five species were collected and fixed in a mixture of ethanol and acetic acid (3:1). The slides were prepared by squashing and staining with 1% propionic carmine. Results showed that during microsporogenesis there were few irregularities, mostly frequently related to chromosome irregular segregation as: precocious migration to poles in metaphase I and II, non-oriented bivalent chromosomes at metaphase I and II, and laggard chromosomes in anaphase I and II, forming micronuclei in telophases I and II and tetrad with microcyte. Another observed irregularity is related to the organization of spindle fibers in meiosis II as they organize themselves in T and V shapes and in sequential spindle. However, in the V-shaped spindle configuration, there was fusion between two nuclei that were close, forming triads instead of tetrads. Irregular chromosome segregation, abnormal spindles and irregularities in the cytokinesis process were responsible for the formation of monads, dyads, triads and polyads. However, the pollen grain viability was not harmed, presenting an 83.98% to 98.59% fertility variation.

O gênero Passiflora, família Passifloraceae, apresentam mais de 500 espécies, havendo no Brasil aproximadamente 120 espécies nativas. Todas as espécies produzem frutos que são utilizados como produtos alimentícios, medicinais e ornamentais. Botões florais de cinco espécies foram coletados e fixados em etanol/acido acético (3:1). As lâminas foram preparadas utilizando a técnica de esmagamento e coradas com carmim propiônico a 1%. Como resultado, observou-se que durante a microsporogênese poucas irregularidades foram encontradas, as mais frequentes estão relacionadas à segregação irregular dos cromossomos, tais como: migração precoce para os pólos em metáfase I e II, bivalente não orientado em metáfase I e II, e cromossomos retardatários em anáfase I e II, levando a formação de micronúcleos em telófases I e II, e micrócito em tétrades. Outra irregularidade observada esta relacionada a organização das fibras dos fusos em meiose II, que se organizam na forma em T, em V e fuso sequencial. Na configuração de fuso na forma de V ocorreu fusão entre dois núcleos que estavam próximos, formando tríade ao invés de tétrade. A segregação irregular dos cromossomos, a formação de fusos anormais e as irregularidades no processo de citocinese foram responsáveis pela formação de mônades, díades, tríades e políades como produtos final da meiose. Porém, a viabilidade dos grãos de pólen não foi comprometida, apresentado uma variação de 83,98% a 98,59% de fertilidade.

Chromosome number and microsporogenesis of two accessions of Brachiaria dura Stapf (Poaceae) / Número de cromossomos e microsporogênese de dois acessos de Brachiaria dura Stapf (Poaceae)

The two accessions of B. dura analyzed (DU01 and DU02) are hexaploid (2n = 6x = 54), derived from x = 9. Meiotic abnormalities, such as precocious chromosome migration to the poles, laggards and micronuclei, were recorded in low frequency in both accessions. The few multivalent chromosome association at diakinesis and meiotic stability suggested that hexaploidy probably resulted from chromosome doubling. In DU02, chromosome transfer (cytomixis) among meiocytes, involving part or the entire genome was observed. The implication of these findings for the Brachiaria breeding is discussed.

Os dois acessos de B. dura analisados (DU01 e DU02) são hexaplóides (2n = 6x = 54), derivados de x = 9. Anormalidades meióticas como migração precoce de cromossomos para os polos, cromossomos retardatários e micronúcleos foram observados em baixa frequência em ambos os acessos. A presença de poucas associações cromossômicas em diacinese e a estabilidade meiótica sugere que a hexaploidia provavelmente resultou de duplicação cromossômica. No acesso DU02 observou-se transferência de cromossomos (citomixia) entre meiócitos, envolvendo parte ou todo o genoma. As implicações destes resultados para o melhoramento de Brachiaria são discutidas.

Cytogenetic evidence for genome elimination during microsporogenesis in interspecific hybrid between Brachiaria ruziziensis and B. brizantha (Poaceae)

Microsporogenesis was analyzed in an interspecific hybrid between an artificially tetraploidized sexual accession of Brachiaria ruziziensis (R genome) and a natural apomictic tetraploid accession of B. brizantha (B genome). Chromosomes associated predominantly as bivalents. From this phase to the end of meiosis, chromosomes presented irregular segregation and abnormal arrangement in the metaphase plate. During metaphase I, in 27.8 percent of meiocytes, bivalents were distributed in two metaphase plates. In anaphase I, two distinct and typical bipolar spindles were formed. In 29.7 percent of pollen mother cells, one genome did not divide synchronically, with chromosomes lagging behind or not segregating at all. The second division was very irregular, resulting in polyads. Based on previous results from analysis of a triploid hybrid between these species, where the R genome was eliminated by asynchrony during meiosis, it is suggested that the laggard genome in this hybrid also belongs to B. ruziziensis.

Normal microspore production after cell fusion in Brachiaria jubata (Gramineae)

Cytogenetic studies were carried out on 22 accessions of Brachiaria jubata from the Embrapa Beef Cattle Brachiaria collection. One accession was diploid (2n = 2x = 18) and the remaining 21 were tetraploid (2n = 4x = 36). Among five tetraploid accessions, a specific and constant pattern of cell fusion involving only two microsporocytes was recorded. Meiosis proceeded normally from prophase I to the end, giving rise to an octad with normal microspores that developed into fertile pollen grains. Regular octad formation was possible because each cellular chromosome set was maintained in its proper domain, spindles were correctly positioned, and cytokinesis planes were formed in the correct places. Such behavior of meiosis in syncytes has never been reported in any other plant species.