Impact of El Niño and malaria on birthweight in two areas of Tanzania with different malaria transmission patterns

BACKGROUND: Malaria infection increases low birthweight especially in primigravidae. Malaria epidemics occur when weather conditions favour this vector borne disease. Forecasting using the El Ni?o Southern Oscillation (ENSO) may assist in anticipating epidemics and reducing the impact of a disease which is an important cause of low birthweight. The aim of the present study was to determine the impact of the malaria epidemic in East Africa during 1997-1998 on birthweights in two different areas of Tanzania and to explore ESNO's potential for forecasting low birthweight risk in pregnant women. METHOD: A retrospective analysis of birthweight differences between primigravidae and multigravidae in relation to malaria cases and rainfall for two different areas of Tanzania: Kagera, which experiences severe outbreaks of malaria, and Morogoro which is holoendemic. Birthweight and parity data and malaria admissions were collected over a 10-year period from two district hospitals in these locations. RESULTS: The risk of delivering a low birthweight baby in the first pregnancy increases approximately 5 months following a malaria epidemic. An epidemic of marked reduced birthweight in primigravidae compared with multigravidae occurred, related to the ENSO of 1997-1998. In Kagera this birthweight difference and the risk of low birthweight were significantly lower compared with Morogoro, except after the ENSO when the two areas had similar differences. No significant interaction was noted between secundigravidae and any of the risk periods. The results indicate that the pressure of malaria is much greater on pregnant women, especially primigravidae, living in the Morogoro location. CONCLUSIONS: Surveillance of birthweight differences between primigravidae and multigravidae is a useful indicator of malaria exposure.     

Identifying high‐risk babies born in the community using foot length measurement at birth in Uganda

Background Low birthweight and prematurity are risk factors for neonatal mortality. Identifying low birthweight and premature babies at birth and giving them appropriate care could increase their chances of survival. This study aimed at assessing the use of foot length as a surrogate for low birthweight and prematurity, and recommending an operational cut‐off for identifying high‐risk babies at the community level in low resource settings. Methods A hospital‐based cross‐sectional study was carried out between 1 September and 17 December 2009 in Uganda. Foot length of 711 newborns was measured using three different methods and their weight taken using a digital salter scale within 24 h of life. Gestational age of the newborns was also estimated using the Eregie method. Non‐parametric receiver operating characteristic curve analysis was carried out to determine the foot length method with the highest predictive value to predict low birthweight and premature newborns. Sensitivity, specificity and predictive values for a range of foot lengths were estimated to determine the optimal cut‐off to predict low birthweight and prematurity in this setting. Results Of the 711 babies recruited on day 1, 85 (12%) babies were low birthweight (<2500 g) and 29 (4%) premature (<37 weeks). The operational cut‐off for foot length to detect small babies was defined as 7.6 cm, with sensitivity 85% [95% confidence interval (CI) 75–92] and specificity 81% (95% CI 78–84) for low birthweight, and sensitivity 96% (95% CI 82–100) and specificity 76% (95% CI 73–79) for premature babies. Conclusion Foot length in the first days of life can predict low birthweight and prematurity among newborn babies in this setting. Further evaluation is needed to assess the feasibility of its use by community health workers to identify babies that need extra care.     

Importance and prevention of malaria in pregnancy

Malaria in pregnancy is one of the most important preventable causes of low birthweight deliveries worldwide. It is also a major cause of severe maternal anaemia contributing to maternal mortality. It is estimated that 40% of the world's pregnant women are exposed to malaria infection during pregnancy. The clinical features of Plasmodium falciparum malaria in pregnancy depend to a large extent on the immune status of the woman, which in turn is determined by her previous exposure to malaria. In pregnant women with little or no pre-existing immunity, such as women from non-endemic areas or travellers to malarious areas, infection is associated with high risks of severe disease with maternal and perinatal mortality. Women are at particular risk of cerebral malaria, hypoglycaemia, pulmonary oedema and severe haemolytic anaemia. Fetal and perinatal loss has been documented to be as high as 60-70% in non-immune women with malaria. Adults who are long-term residents of areas of moderate or high malaria transmission, including large parts of sub-Saharan Africa, usually have a high level of immunity to malaria. Infection is frequently asymptomatic and severe disease is uncommon. During pregnancy this immunity to malaria is altered. Infection is still frequently asymptomatic, so may go unsuspected and undetected, but is associated with placental parasitization. Malaria in pregnancy is a common cause of severe maternal anaemia and low birthweight babies, these complications being more common in primigravidae than multigravidae. Preventative strategies include regular chemoprophylaxis, intermittent preventative treatment with antimalarials and insecticide-treated bednets.     

Predicting low birthweight and complicated labor in urban black women: A biopsychosocial perspective

This study explored demographic, biomedical and psychosocial factors as predictors of two adverse pregnancy outcomes: intrapartum complications and low birthweight, in 140 urban black pregnant women. The intrapartum complication rate was 18%. A four factor equation (low family functioning, advanced maternal age, working during pregnancy, and short stature) predicted intrapartum complications (80% sensitivity, 67% specificity and 35% positive predictive value). The low birthweight rate was 14%. Four factors (low family functioning, stressful events, Quetelet's Index, and cigarette smoking) predicted low birthweight (65% sensitivity, 84% specificity and 42% positive predictive value). Family functioning, alone, predicted low birthweight with 65% sensitivity, 64% specificity and 31% positive predictive value. Family functioning, was the only predictor for both outcomes. Family functioning and other psychosocial risk factors may potentially improve identification of high risk pregnant urban black women.     

Malaria in pregnancy as an indirect cause of infant mortality in sub-Saharan Africa

Although randomized controlled trials of interventions to reduce malaria in pregnancy have demonstrated an increase in the birthweight of the newborn in primigravidae, the subsequent impact on infant mortality in all-parities has not been assessed. The aim of this paper was to model the possible impact of placental malarial infection on infant mortality through reduced birthweight. An extensive literature search was undertaken to define a series of parameters describing the associations between placental infection, birthweight and premature mortality in sub-Saharan Africa. It was shown that a baby is twice as likely to be born of low birthweight if the mother has an infected placenta at the time of delivery (all-parities: 23% vs 11%, primigravidae only: 32% vs 16%), and that the probability of premature mortality of African newborns in the first year of life is 3 times higher in babies of low birthweight than in those of normal birthweight (16% vs 4.6%). Assuming 25% of pregnant women in malaria-endemic areas of Africa harbour placental malarial infection, it is suggested that 5.7% of infant deaths in malarious areas could be an indirect cause of malaria in pregnancy. This would imply that, in 1997, malaria in pregnancy could have been responsible for around 3700 infant deaths under the diverse epidemiological conditions in Kenya. Placental infection with Plasmodium falciparum appears to have a more significant role in infant survival in Africa than has been previously assumed. This may explain the high reduction in infant mortality rates from interventions aimed at reducing transmission, over and above that expected from a decline in direct malaria-specific mortality alone.     

Distribution and determinants of low birthweight in Central Sudan

Summary. Two studies were conducted during 1989-90 in Central Sudan to determine the incidence of low birthweight and to ascertain the major risk factors which influence birthweight. In a hospital-based investigation, surveillance of all births was accompanied by a nested case-control study, and in a community based investigation, all midwife-assisted births were studied. There were 4868 and 1523 livebirths among the hospital and community populations, respectively. The incidence of low birthweight was 18.1% in the community and 8.2% in the hospitals. The ratio of term to pre-term low birthweight was 2.9 in the community but only 1.3 in the hospitals. Several risk factors showed consistent and significant associations with low birthweight in the hospital and community studies. Two important and modifiable predictors of term and preterm low birthweight were low maternal weight and malaria infection during pregnancy. Other risk factors included low socio-economic status and, among the hospital population, lack of antenatal care, short birth intervals, poor obstetric history and complications of pregnancy.     

Individual and Community Predictors of Preterm Birth and Low Birthweight Along the Rural-Urban Continuum in Central Pennsylvania

CONTEXT: Preterm birth and low birthweight remain high priority public health problems and are associated with increased risk of infant mortality as well as long-term health impairments. Although 20% of all births nationally are to rural women, relatively little attention has been paid to pregnancy outcomes in rural areas relative to more urbanized areas. PURPOSE: This study examines the relationship of individual- and community-level socioeconomic, health care, and health status-related characteristics to preterm birth and low birthweight outcomes among women living in urban and various types of rural communities. METHODS: Vital record data on singleton first births to residents of a 28-county region in central Pennsylvania in 2002 (N = 11,546) were merged with zip code-level information from the census and residence in a primary care health professional shortage area. Rural-urban commuting area codes were also appended. Multiple logistic regression analyses were performed to model risks of preterm birth and low birthweight using generalized estimating equations to account for clustering within zip code. FINDINGS: Women residing in large rural city-focused areas had lower adjusted odds of both preterm birth and low birthweight as compared to urban women, controlling for individual risk factors including maternal demographic characteristics, health conditions, and prenatal care use. In contrast, risks of these adverse birth outcomes were not significantly lower among women living in more rural areas relative to those in urban communities. CONCLUSIONS: Reduced risks of preterm birth and low birthweight risk are associated with some, but not all types of rural as compared to urban communities.     

Seasonality of births and birthweights in Tanzania

Seasonal patterns of birthrates and birthweights have been compiled from the delivery records of 11 rural hospitals and compared with each other and with the local rainfall pattern by means of lagged regression analysis. While mean birthweight is lower in high rainfall areas, both magnitude and predictability of seasonal birthweight variations are greater in low rainfall areas. Such differences are attributed to different combinations of infection rates, dietary intake and reliability of food supply. Seasonal variations in birthrate were found to occur independently from those of birthweight. Birth seasonality was found to be prominent only in areas with holoendemic malaria and is attributed to a seasonal depression of fecundity mainly due to malaria infection.     

Low birthweight and socioeconomic status,Victoria 1982 to 1986

Abstract: The aim of this study was to evaluate the association between the incidence of low birthweight and socioeconomic status, in particular whether the relationship was different for very low birthweight (< 1500 g) and moderately low birthweight (1500 to 2499 g). The study population was births from 1982 to 1986 to women resident in Victoria (300 704). Data on socioeconomic status were derived from an indicator developed by the Australian Bureau of Statistics from the 1981 census and applied to postcodes. Using the rates of very low birthweight and moderately low birthweight in the highest socioeconomic status decile as the reference value we found that the relative risk for very low birthweight was significantly raised in only the lowest socioeconomic status decile (relative risk = 1.29, 95% confidence interval (CI) 1.17 to 1.42). The relative risk for moderately low birthweight was increased in the two lowest deciles: 1.19 (CI 1.12 to 1.26) and 1.09 (CI 1.01 to 1.17) respectively. Women not married at the time of the birth had a higher rate of low birthweight and were more likely to live in the lower socioeconomic status postcode areas. The relationships between very low birthweight, moderately low birthweight and socioeconomic status were attenuated but still significant when this factor was taken into account. Differences in low birthweight by socioeconomic status decile were not apparent for nonsmoking women. The relationship between smoking and low birthweight was different in the two lowest socioeconomic status deciles: the relative risk of low birthweight in smokers was 2.60 (CI 1.73 to 3.91) compared with a relative risk of 1.64 (CI 1.33 to 2.03) in deciles 3 to 10.     

Pregnancy and Birth Outcomes Among Primiparae at Very Advanced Maternal Age: At What Price?

Objectives In light of the potential physical and emotional costs to both woman and child, this study was conducted to assess pregnancy complications and birth outcomes in primiparae at very advanced maternal age (VAMA, aged ≥45) compared to younger primiparae. Methods Retrospective cohort study comparing 222 VAMA primiparae and a reference group of 222 primiparae aged 30–35, delivering at Sheba Medical Center from 2008 through 2013.Results VAMA primiparae were more likely than younger primiparae to be single, to have chronic health conditions, and higher rates of gestational diabetes mellitus (GDM), gestational-hypertension (GHTN) and preeclampsia-eclampsia. VAMA primiparae conceived mostly by oocyte donation. They were more likely to be hospitalized during pregnancy, to deliver preterm and by cesarean birth. Infants of VAMA primiparae were at greater risk for low birthweight and Neonatal Intensive Care Unit admission. There were no differences in outcomes between VAMA primiparae with or without preexisting chronic conditions, or between those aged 45–49 and ≥50. In multivariable analysis VAMA was an independent risk factor for GDM, GHTN and preeclamsia-eclampsia, with adjusted odds ratio of 2.38 (95 % CI 1.32, 4.29), 5.80 (95 % CI 2.66, 12.64) and 2.45 (95 % CI 1.03, 5.85); respectively. The effect of age disappeared in multiple pregnancies. Conclusions Primiparity at VAMA holds a significant risk for adverse pregnancy and birth outcomes. The absence of chronic medical conditions or the use of a young oocyte donor does not improve these outcomes. Multiple pregnancies hold additional risk and may diminish the effect of age. Primiparity at an earlier age should be encouraged.     

Estimation of effectiveness of interventions for malaria control in pregnancy using the screening method

BACKGROUND: The evaluation of the effectiveness of antimalarial drugs and bed net use in pregnant women is an important aspect of monitoring and surveillance of malaria control in pregnancy. In principle the screening method for assessing vaccine efficacy can be applied in non-vaccine settings for assessing interventions for malaria control in pregnancy. METHODS: In this analysis field data on the proportion of placental malaria cases treated with two doses of sulphadoxine-pyrimethamine (SP) and the uptake of two doses of SP in the antenatal clinic was used in a case-coverage method to assess the protective effectiveness (PE) of intermittent preventive treatment with SP for malaria control in pregnancy. PE was assessed using placental malaria, low birthweight and maternal anaemia at delivery as outcome variables. The method was also applied to an evaluation of the protective effectiveness of self-reported use of impregnated bed nets (ITNs). RESULTS: Effectiveness was highest for reduction of low birthweight in multigravidae (87.2%, 95% CI, 83.2-91.3%). PE was lower for placental malaria (61.6% primigravidae, 28.5% multigravidae), and maternal anaemia (Hb < 8.0 g/dl, 37.8% primigravidae, 29.6% multigravidae). Estimates for PE of self-reported use of ITNs gave values for all three outcome parameters that were much lower than for SP use. For women of all parties effectiveness estimates for reduction of low birthweight were 22% (95% CI, 17.7-26.4), prevention of placental malaria (all types) 7.1% (95% CI, 4.4-9.8), prevention of active placental infection 38.9% (95% CI, 27.4-50.4), and for maternal anaemia 8.8% (95% CI, 0-20.0). CONCLUSIONS: The case-coverage method could provide a useful and practical approach to routine monitoring and evaluation of drug interventions to control malaria in pregnancy and has potentially wide applications. Effectiveness estimates related to reported ITN use in pregnancy may be less reliable. The method should be further evaluated using currently available data sets.     

Attributable fraction estimates and case definitions for malaria in endemic

Asymptomatic carriage of malaria parasites occurs frequently in endemic areas and the detection of parasites in a blood film from a febrile individual does not necessarily indicate clinical malaria. In areas of low and moderate endemicity the parasite prevalence in fever cases can be compared with that in community controls to estimate the fraction of cases which are attributable to malaria. In areas of very high transmission such estimates of the attributable fraction may be imprecise because very few individuals are without parasites. Furthermore, non-malarial fevers appear to suppress low levels of parasitaemia resulting in biased estimates of the attributable fraction. Alternative estimation techniques were therefore explored using data collected during 1989-1991 from a highly endemic area of Tanzania, where over 80 per cent of young children are parasitaemic. Logistic regression methods which model fever risk as a continuous function of parasite density give more precise estimates than simple analyses of parasite prevalence and overcome problems of bias caused by the effects of non-malarial fevers. Such models can be used to estimate the probability that any individual episode is malaria-attributable and can be extended to allow for covariates. A case definition for symptomatic malaria that is used widely in endemic areas requires fever together with a parasite density above a specific cutoff. The choice of a cutoff value can be assisted by using the probabilities derived from the logistic model to estimate the sensitivity and specificity of the case definition.     

Epidemiologic evaluation of screening for risk factors: application to genetic screening.

To assess the usefulness of screening for risk factors, we derived arithmetic relationships between screening parameters (sensitivity, specificity, and positive predictive value PPV) and risk factor frequency, disease frequency and relative risk. We evaluated these relationships in the special case of genetic markers and disease susceptibility. It can be shown that even in the face of very large relative risks, sensitivity and positive predictive value are affected by the relative magnitude of disease and genetic marker frequencies. When the genetic marker is less frequent than the disease, PPV increases with increasing relative risk but sensitivity remains low. When the genetic marker is more frequent than the disease, sensitivity increases with increasing relative risk but PPV remains low. When marker and disease frequencies are equal, both PPV and sensitivity increase with increasing relative risks, but very high relative risks (greater than 100) have to be obtained for rare diseases. Depending on the goals of the screening program, these relationships can be used to predict the relative magnitudes of false positives (low PPV) and false negatives (low sensitivity). This approach can be generalized to evaluate nongenetic risk factors in screening programs as well.     

Family history as a predictor of asthma risk

Asthma, one of the most important chronic diseases of children, disproportionately affects minority and low-income children. Many environmental risk factors for asthma have been identified, including animal, mite, and other allergens; cigarette smoke; and air pollutants. Genetics also play an important causative role, as indicated by familial aggregation and the identification of candidate genes and chromosomal regions linked to asthma risk. Using a positive family history of asthma to identify children at increased risk could provide a basis for targeted prevention efforts, aimed at reducing exposure to environmental risk factors.To assess the predictive value of family history as an indicator of risk for childhood asthma, we reviewed population-based studies that evaluated family history of asthma and atopic disease in children with asthma.Our search identified 33 studies from all geographic regions of the world for review. The studies varied in definitions of positive family history and asthma phenotype and used study populations with asthma prevalence ranging from 2% to 26%. Nevertheless, family history of asthma in one or more first-degree relatives was consistently identified as a risk factor for asthma. In ten studies, sensitivity and predictive value of a positive family history of asthma could be calculated: sensitivity ranged from 4% to 43%, positive predictive value from 11% to 37%, and negative predictive value from 86% to 97%.Although a positive family history predicts an increased risk of asthma, it identifies a minority of children at risk. Positive family history may have utility in targeting some individual prevention efforts, but the low positive predictive value limits its value as a means to direct environmental remediation efforts.     

Appreciating the complexity of localized malaria risk in Ghana: Spatial data challenges and solutions

Various factors have been associated with the ongoing high prevalence of malaria in Ghana. Among these are poor sanitation, low socioeconomic status (SES), building construction and other proximate micro environmental risks, and individual behaviors. What makes the curbing of malaria more challenging, is that for many of the most impacted areas there is little data for modeling or predictions, which are needed, as risk is not homogenous at the sub-neighborhood scale. In this study we use available local surveillance data combined with novel on-the-ground fine scale environmental data collection, to gain an initial understanding of malaria risk for the Teshie township of Accra, Ghana. Mapped environmental risk factors include open drains, stagnant water and trash. Overlaid onto these were clinical data of reported malaria cases collected between 2012 and 2016 at LEKMA hospital. We then enrich these maps with local context using a new method for malaria research, spatial video geonarratives (SVGs). These SVGs provide insights into the underlying spatial-social patterns of risks, to reveal where traditional data collection is lacking, and how and where to develop local intervention strategies.     

The effect of a preterm birth prevention program in 17 rural and three urban counties in northwest North Carolina.

The results of a program of low birthweight prevention in 17 rural (20,727 births) and three urban counties (15,561 births) for calendar years 1985 and 1986 are described. Records for women in the program were matched with birth certificate data by computer. Rural and urban women in and out of the program were compared by race on the following risk factors: age less than 18 years, unmarried, education less than 12 years, Medicaid recipient, not WIC recipient, inadequate prenatal care, and previous fetal or live born death. Adjusting for these risk factors, logistic regression was used to estimate program effects on low birthweight (LBW), very low birthweight (VLBW), and preterm low birthweight (PLBW) among rural women. There was a statistically significant difference (p less than or equal to 0.01) favoring women in the program for very low birthweight and preterm low birthweight in white women, and low birthweight and preterm low birthweight in nonwhite women. The differences in rural areas exceed those in urban areas for all but one mean, very low birthweight births among white women.     

Maternal age and parity-associated risks of preterm birth: differences by race/ethnicity

There is a well-known interaction between maternal age and parity in the risk of adverse perinatal outcomes, including preterm birth (PTB), such that young multiparae and older primiparae have greater risks. Yet it is not known whether this interaction varies by race/ethnicity. US birth records for singleton births from 2000 to 2002 were used to examine the incidence of PTB by maternal age and parity within non-Hispanic White, non-Hispanic Black and Hispanic subgroups. PTB was categorised as moderately (32-36 weeks), very (28-31 weeks), or extremely (<28 weeks) preterm. Odds ratios of PTB according to age and parity were calculated in racial/ethnic specific multinomial logistic regression models. Within each race/ethnicity, comparisons were made relative to 25- to 29-year-old primiparae. Young teenagers (<18), particularly multiparae, generally had a higher risk of each degree of PTB among all three racial/ethnic groups. However, Black teenagers did not have a higher risk of extremely PTB. For very and extremely PTB, teenagers had considerably higher risk among Whites than Blacks or Hispanics. Within each racial/ethnic group, older (35+ years) primiparae had similarly higher risk of each category of PTB relative to 25- to 29-year-old primiparae. Older multiparae had higher risk of moderately and very PTB among Black and Hispanic women only. Adjustment for education did not alter these findings. Teenagers and older primiparae are already widely regarded as having greater perinatal risks. This study suggests that, among Black and Hispanic women, older multiparae may also have a higher risk of moderately and very PTB.     

基于TOPSIS法疟疾防治系统脆弱性评估

目的 评估中国疟疾防治系统的脆弱性,为疟疾的风险管理提供策略建议。方法 采用分层随机抽样和典型抽样相结合的方法于2015年7月-2016年2月在湖北、安徽和广西3个省共抽取8个样本县（区）,通过文献检索、小组头脑风暴和专家咨询等方法编制调查问卷对样本县（区）疟疾流行现状和居民的疟疾防治知识进行调查,选出代表性指标,运用TOPSIS法对样本县（区）的疟疾防治系统脆弱性进行评估。结果 通过文献检索、小组头脑风暴和专家咨询,最终选取经济脆弱性、社会脆弱性、政治脆弱性、卫生系统脆弱性和敏感性5个维度共19个指标,权重系数为0.009 2~0.103 7,其中,疫区流入人员数量（0.100 6）和政府疟疾风险关注度（0.103 7）权重系数较大;中国8个样本县（区）疟疾防治系统脆弱性从高到低依次为湖北省潜江市（0.652 42）、安徽省淮南田家庵区（0.578 39）、安徽省肥西县（0.509 58）、湖北省广水市（0.459 92）、广西省都安县（0.405 82）、安徽省淮南谢家集区（0.369 89）、广西省天峨县（0.234 74）、广西省南丹县（0.181 66）,总体的系统脆弱性不高。结论 中国疟疾防治系统总体脆弱性不高,政府疟疾风险关注度和疫区流入人员数量是影响疟疾防治系统脆弱性最为重要的风险因素。