[Risk factors for repetition of low birth weight, intrauterine growth retardation, and prematurity in subsequent pregnancies: a systematic review]

Potential pregnancy days lost: an innovative measure of gestational age

In Brazil, the excess of interventions that anticipate childbirth, such as cesarean sections and labor inductions, has resulted in the shortening of pregnancy, with negative consequences on maternal-infant outcomes. This commentary presents a novel way to measure gestational age: the continuous variable "Potential pregnancy days lost." Using data from the Live Birth Information System (SINASC), we counted the missing days between the period until childbirth and the average duration of pregnancy (280 days), or the lost weeks. This measure can be used as an outcome variable (socioeconomic-demographic characteristics of the mother, type of childbirth, financing, etc.) or exposure variable (for neonatal, infant, and maternal outcomes). The indicator can be used in municipal and national cohorts and intervention studies to analyze hospitals and regions. We discuss the limits and scope of gestational age measures and, given their inaccuracies, the importance of studying their trends.

Association between maternal lifestyle factors and low birth weight in preterm and term births: a case-control study

Background

It has been reported that lifestyle factors may affect birth weight; however, few studies have explored the association between lifestyle factors and low birth weight in preterm and term births in China. The objective of this study was to explore the effect of lifestyle on low birth weight in preterm and term births.

Methods

This case-control study was conducted in fourteen hospitals in Jiangmen, Guangdong Province. Data were collected from August 2015 to May 2016 using a standard questionnaire. Data were analysed using logistic regression.

Results

Women who delivered preterm and were physically active (1–3 times per week and ≥ 4 times per week) had reduced odds of having low birth weight babies (aOR = 0.584, 95%CI = 0.394–0.867 and, aOR = 0.516, 95%CI = 0.355–0.752, respectively). Pregnant women who had insufficient gestational weight gain had increased odds of having low birth weight babies (aOR = 2.272, 95%CI = 1.626–3.176). Women exposed to passive smoking had an increased risk of delivering low birth weight infants (aOR = 1.404, 95%CI = 1.057–1.864). Insufficient gestational weight gain and excessive gestational weight gain were both significantly associated with low birth weight (aOR = 1.484, 95%CI = 1.103–1.998 and aOR = 0.369, 95%CI = 0.236–0.577, respectively) for term deliveries. In addition, parity, history of low birth weight, antenatal care and gestational hypertension were significantly associated with the likelihood of low birth weight.

Conclusion

Pregnant women without exercise contraindications should remain physically active. Pregnant women should be aware of the negative effects of smoke and be aware of strategies to protect themselves from passive smoke exposure. Hospitals should inform pregnant women of the importance appropriate gestational weight gain. These recommendations should be put into practice to decrease the prevalence of low birth weight infants.

Developmental defects of enamel in primary teeth: highly prevalent, unevenly distributed in the oral cavity and not associated with birth weight

AIM

Estimate the prevalence of developmental defects of enamel (DDE) in the primary dentition, describe the distribution among tooth groups and investigate the association with birth weight.

METHODS

A cross-sectional study was conducted with a sample of 827 children aged 2-5 years representative of the city of Canela in southern Brazil. Demographic characteristics (gender and age) and birth weight were collected from vaccination cards. The diagnosis of DDE was performed by six trained examiners following the criteria of the Federation Dentaire International. DDE were described both jointly and separately as opacity and hypoplasia. Statistical analysis involved the Chi square test, Mann-Whitney test and Poisson regression with robust variance.

RESULTS

The prevalence of DDE was 55.1% (95% CI 51.6-58.5%), with a mean of 3.0 ± 2.2 teeth affected. Opacity was the more frequent defect (50.4%), followed by hypoplasia (15.5%). Distribution of the defects was uneven, with opacity predominant on second molars and hypoplasia predominant on canines and second molars. Children with a low birth weight did not have a greater probability of opacity (PR: 1.13; 95% CI 0.91-1.41), hypoplasia (PR: 1.33; 95% CI 0.80-2.22) or DDE (PR: 1.11; 95% CI 0.91-1.37).

CONCLUSION

The prevalence of DDE was high, predominant on second molars and not associated with birth weight. These findings indicate directions for future examination/diagnosis protocols and specific orientations.

Birth history as a predictor of adverse birth outcomes: Evidence from state vital statistics data

One of the most important predictors of preterm births (PTBs) or low-birth-weight births (LBWBs) is whether a mother has had a history of these birth outcomes. This study examined how different characterizations of birth history (e.g., any previous incidence of PTBs or LBWBs, immediate previous birth that was preterm or of low birth weight, and number of previous PTBs or LBWBs) were associated with PTBs or LBWBs. Based on birth records (n = 98,776) reported to the vital statistics electronic registration system in Nebraska from 2005 to 2014, mothers with a history of PTBs or LBWBs were more likely to have recurrences of these outcomes than those who did not have any history of PTBs or LBWBs. The adjusted odds ratios for recurrent PTBs ranged from 2.82 (95% CI: 2.62, 3.04) to 5.54 (95% CI: 4.67, 6.57) depending on how previous incidence of PTBs or LBWBs were characterized. The corresponding adjusted odds ratio for LBWBs ranged from 1.58 (95% CI: 1.43, 1.74) to 6.75 (95% CI: 4.96, 9.17). Relative to other measures used to characterize birth history, the use of number of previous PTBs or LBWBs allows for identifying mothers most vulnerable to recurrences of these birth outcomes. To help identify mothers at risk for future PTBs or LBWBs, it is beneficial to develop state-wide surveillance of reoccurrences for adverse birth outcomes which is feasible by integrating all separated birth records for the same mother using vital statistics data.

Fish consumption during pregnancy, mercury transfer, and birth weight along the Madeira River Basin in Amazonia

Birth weight can be a predictor of maternal health issues related to nutrition and environmental contaminants. Total hair mercury (HHg) concentration was studied as an indicator of both fish consumption and methylmercury exposure in mothers (and newborns) living in selected low income areas of the Madeira River basin, Amazonia, Brazil. This cohort study (n = 1,433) consisted of traditional riverines (n = 396), riverines who had moved to urban (n = 676) and rural (n = 67) settings, and tin miner settlers (n = 294). Median maternal HHg was significantly different (p = 0.00001) between riverine (12.1 µg·g⁻¹), rural (7.82 µg·g⁻¹), urban (5.4 µg·g⁻¹), and tin miner (4.5 µg·g⁻¹) groups studied. The same trend (of medians) was observed for newborns’ HHg which also showed significant differences between riverine (3.0 µg·g⁻¹), rural (2.0 µg·g⁻¹), urban (1.5 µg·g⁻¹), and tin miner (0.8 µg·g⁻¹) groups. The correlation between maternal and newborn HHg was statistically significant in the riverine (r = 0.8952; p = 0.0001), urban (r = 0.6744; p = 0.0001), and rural (r = 0.8416; p = 0.0001) groups but not in the mother-infant pairs in the tin miner group (r = 0.0638; p = 0.2752). Birth weight was significantly different among groups but did not show a pattern consistent with that of fish consumption (and HHg). A multiple regression analysis showed that only family income and gestational age had a significant impact on birth weight. Conclusions: Maternal HHg is an important biomarker of maternal fish consumption and of methylmercury exposure during pregnancy. However, in these Amazonian groups, only maternal education and gestational age seemed to affect birth weight positively.

[Evidence-based practices published in Brazil: identification and analysis studies about human health prevention]

Integrative review of Brazilian studies about evidence-based practices (EBP) about prevention in human health, published in Web of Science/JCR journals, between October 2010 and April 2011. The aim was to identify the specialties that most accomplished these studies, their foci and methodological approaches. Based on inclusion criteria, 84 studies were selected, mainly published in public health journals, focusing on primary care and also addressing clinical issues and different specialties. Prevention foci and methodological approaches also varied, with a predominance of systematic reviews without meta-analysis. The results indicate that there is no single way to conceptualize and practice EBP in the field of prevention, and that its application may not only serve to obtain indisputable evidence to equip intervention actions. This endless knowledge area is under construction, with a view to the analysis and further understanding of health phenomena.

Prognostic factors for low birthweight repetition in successive pregnancies: a cohort study

Background

To identify prognostic factors associated with recurrence of low birthweight (LBW) in successive gestations, a study was carried out with a subsample of mothers enrolled in the 2004 Pelotas Birth Cohort.

Methods

Data were collected by hospital-based interviews. Newborns were weighed and measured. Gestational age was defined according to the date of last menstrual period, ultra-sound scan before the 20^th week of pregnancy or the Dubowitz method. Mothers who reported at least one LBW newborn in the two previous gestations were included. Prevalence ratios (PR) and 95% confidence intervals were estimated from Poisson Regression. All estimates were adjusted for parity.

Results

A total of 4558 births were identified in 2004, and 565 met inclusion criteria, out of which 86 (15.2%) repeated LBW in 2004. Among mothers with two LBW babies before 2004, 47.9% presented LBW recurrence. Belonging to the highest socio-economic stratum (PR 0.89; 0.01-0.46) and gaining ≥ 10 kg during pregnancy (PR 0.09; 0.01-0.77) were protective against LBW recurrence. Higher risk of LBW recurrence was observed among mothers with higher parity (≥3 previous deliveries; PR=1.93; 95% CI 1.23-3.02); who had given birth to a previous preterm baby (PR=4.01; 2.27-7.10); who delivered a female newborn in current gestation (PR=2.61; 1.45-4.69); and that had not received adequate antenatal care (PR=2.57; 1-37-4.81).

Conclusion

Improved quality of antenatal care and adequate maternal weight gain during pregnancy may be feasible strategies to prevent LBW repetition in successive pregnancies.

[Evidence-based practices published in Brazil: identification and analysis of their types and methodological approches]

This is an integrative review of Brazilian studies on evidence-based practices (EBP) in health, published in ISI/JCR journals in the last 10 years. The aim was to identify the specialty areas that most accomplished these studies, their foci and methodological approaches. Based on inclusion criteria, 144 studies were selected. The results indicate that most EBP studies addressed childhood and adolescence, infectious diseases, psychiatrics/mental health and surgery. The predominant foci were prevention, treatment/rehabilitation, diagnosis and assessment. The most used methods were systematic review with or without meta-analysis, protocol review or synthesis of available evidence studies, and integrative review. A strong multiprofessional expansion of EBP is found in Brazil, contributing to the search for more selective practices by collecting, recognizing and critically analyzing the produced knowledge. The study also contributes to the analysis itself of ways to do research and new research possibilities.

Association between stress and breast cancer in women: a meta-analysis

The objective of the current meta-analysis was to verify the association between stressful life events and primary breast cancer incidence in women. A total of 618 studies from 1982-2007 were found in the PubMed, LILACS, and Cochrane Library databases. Methodological quality was evaluated according to the Downs & Black criteria. Eight studies were selected (six case-controls and two cohorts). The studies were grouped in three analyses, two of which based on the categories widowhood and divorce and the other based on self-rated intensity and frequency of stressful events. Relative risks were: widowhood 1.04 (95%CI: 0.75-1.44; p = 0.800); divorce 1.03 (95%: 0.72-1.48; p = 0.850); and intensity/frequency of stress 1.73 (95%CI: 0.98-3.05; p = 0.059). We conclude that stressful life events as a whole are not associated with risk of breast cancer in women. However, it is not possible to rule out high-intensity stress as a risk factor for breast cancer.