Causes of preterm delivery and intrauterine growth retardation in a malaria endemic region of Papua New Guinea

Global prevalence of preterm birth among Pacific Islanders: A systematic review and meta-analysis

The epidemiology of preterm birth among Pacific Islanders is minimally understood. The purpose of this study was to estimate pooled prevalence of preterm birth among Pacific Islanders and to estimate their risk of preterm birth compared to White/European women. We searched MEDLINE, EMBASE, Web of Science Core Collection, Cochrane Library, CINAHL, Global Health, and two regional journals in March 2023. Observational studies were included if they reported preterm birth-related outcomes among Pacific Islanders. Random-effects models were used to estimate the pooled prevalence of preterm birth with 95% confidence interval (CI). Bayes meta-analysis was conducted to estimate pooled odds ratios (OR) with 95% highest posterior density intervals (HPDI). The Joanna Briggs Institute checklists were used for risk of bias assessment. We estimated preterm birth prevalence among Pacific Islanders in the United States (US, 11.8%, sample size [SS] = 209,930, 95% CI 10.8%-12.8%), the US-Affiliated Pacific Islands (USAPI, SS = 29,036, 6.7%, 95% CI 4.9%-9.0%), New Zealand (SS = 252,162, 7.7%, 95% CI 7.1%-8.3%), Australia (SS = 20,225, 6.1%, 95% CI 4.2%-8.7%), and Papua New Guinea (SS = 2,647, 7.0%, 95% CI 5.6%-8.8%). Pacific Islanders resident in the US were more likely to experience preterm birth compared to White women (OR = 1.45, 95% HPDI 1.32-1.58), but in New Zealand their risk was similar (OR = 1.00, 95% HPDI 0.83-1.16) to European women. Existing literature indicates that Pacific Islanders in the US had a higher prevalence of preterm birth and experienced health inequities. Learning from New Zealand's culturally-sensitive approach to health care provision may provide a starting point for addressing disparities. The limited number of studies identified may contribute to higher risk of bias and the heterogeneity in our estimates; more data is needed to understand the true burden of preterm birth in the Pacific region.

Global estimates of pregnancies at risk of Plasmodium falciparum and Plasmodium vivax infection in 2020 and changes in risk patterns since 2000

BACKGROUND

Women are at risk of severe adverse pregnancy outcomes attributable to Plasmodium spp. infection in malaria-endemic areas. Malaria control efforts since 2000 have aimed to reduce this burden of disease.

METHODS

We used data from the Malaria Atlas Project and WorldPop to calculate global pregnancies at-risk of Plasmodium spp. infection. We categorised pregnancies as occurring in areas of stable and unstable P. falciparum and P. vivax transmission. We further stratified stable endemicity as hypo-endemic, meso-endemic, hyper-endemic, or holo-endemic, and estimated pregnancies at risk in 2000, 2005, 2010, 2015, 2017, and 2020.

FINDINGS

In 2020, globally 120.4M pregnancies were at risk of P. falciparum, two-thirds (81.0M, 67.3%) were in areas of stable transmission; 85 2M pregnancies were at risk of P. vivax, 93.9% (80.0M) were in areas of stable transmission. An estimated 64.6M pregnancies were in areas with both P. falciparum and P. vivax transmission. The number of pregnancies at risk of each of P. falciparum and P. vivax worldwide decreased between 2000 and 2020, with the exception of sub-Saharan Africa, where the total number of pregnancies at risk of P. falciparum increased from 37 3M in 2000 to 52 4M in 2020.

INTERPRETATION

Historic investments in malaria control have reduced the number of women at risk of malaria in pregnancy in all endemic regions except sub-Saharan Africa. Population growth in Africa has outpaced reductions in malaria prevalence. Interventions that reduce the risk of malaria in pregnancy are needed as much today as ever.

Risk factors and pregnancy outcomes associated with placental malaria in a prospective cohort of Papua New Guinean women

Background

Plasmodium falciparum in pregnancy results in substantial poor health outcomes for both mother and child, particularly in young, primigravid mothers who are at greatest risk of placental malaria (PM) infection. Complications of PM include maternal anaemia, low birth weight and preterm delivery, which contribute to maternal and infant morbidity and mortality in coastal Papua New Guinea (PNG).

Methods

Placental biopsies were examined from 1451 pregnant women who were enrolled in a malaria prevention study at 14–26 weeks gestation. Clinical and demographic information were collected at first antenatal clinic visits and women were followed until delivery. Placental biopsies were collected and examined for PM using histology. The presence of infected erythrocytes and/or the malaria pigment in monocytes or fibrin was used to determine the type of placental infection.

Results

Of 1451 placentas examined, PM infection was detected in 269 (18.5%), of which 54 (3.7%) were acute, 55 (3.8%) chronic, and 160 (11.0%) were past infections. Risk factors for PM included residing in rural areas (adjusted odds ratio (AOR) 3.65, 95% CI 1.76–7.51; p ≤ 0.001), being primigravid (AOR 2.45, 95% CI 1.26–4.77; p = 0.008) and having symptomatic malaria during pregnancy (AOR 2.05, 95% CI 1.16–3.62; p = 0.013). After adjustment for covariates, compared to uninfected women, acute infections (AOR 1.97, 95% CI 0.98–3.95; p = 0.056) were associated with low birth weight babies, whereas chronic infections were associated with preterm delivery (AOR 3.92, 95% CI 1.64–9.38; p = 0.002) and anaemia (AOR 2.22, 95% CI 1.02–4.84; p = 0.045).

Conclusions

Among pregnant PNG women receiving at least one dose of intermittent preventive treatment in pregnancy and using insecticide-treated bed nets, active PM infections were associated with adverse outcomes. Improved malaria prevention is required to optimize pregnancy outcomes.

Effects of Plasmodium falciparum infection on umbilical artery resistance and intrafetal blood flow distribution: a Doppler ultrasound study from Papua New Guinea

Background

Doppler velocimetry studies of umbilical artery (UA) and middle cerebral artery (MCA) flow help to determine the presence and severity of fetal growth restriction. Increased UA resistance and reduced MCA pulsatility may indicate increased placental resistance and intrafetal blood flow redistribution. Malaria causes low birth weight and fetal growth restriction, but few studies have assessed its effects on uteroplacental and fetoplacental blood flow.

Methods

Colour-pulsed Doppler ultrasound was used to assess UA and MCA flow in 396 Papua New Guinean singleton fetuses. Abnormal flow was defined as an UA resistance index above the 90th centile, and/or a MCA pulsatility index and cerebroplacental ratio (ratio of MCA and UA pulsatility index) below the 10th centile of population-specific models fitted to the data. Associations between malaria (peripheral infection prior to and at ultrasound examination, and any gestational infection, i.e., ‘exposure’) and abnormal flow, and between abnormal flow and birth outcomes, were estimated.

Results

Of 78 malaria infection episodes detected before or at the ultrasound visit, 62 (79.5%) were Plasmodium falciparum (34 sub-microscopic infections), and 16 were Plasmodium vivax. Plasmodium falciparum infection before or at Doppler measurement was associated with increased UA resistance (adjusted odds ratio (aOR) 2.3 95% CI 1.0–5.2, P = 0.047). When assessed by ‘exposure’, P. falciparum infection was significantly associated with increased UA resistance (all infections: 2.4, 1.1–4.9, P = 0.024; sub-microscopic infections 2.6, 1.0–6.6, P = 0.051) and a reduced MCA pulsatility index (all infections: 2.6, 1.2–5.3, P = 0.012; sub-microscopic infections: 2.8, 1.1–7.5, P = 0.035). Sub-microscopic P. falciparum infections were additionally associated with a reduced cerebroplacental ratio (3.64, 1.22–10.88, P = 0.021). There were too few P. vivax infections to draw robust conclusions. An increased UA resistance index was associated with histological evidence of placental malaria (5.1, 2.3–10.9, P < 0.001; sensitivity 0.26, specificity 0.93). A low cerebroplacental Doppler ratio was associated with concurrently measuring small-for-gestational-age, and with low birth weight.

Discussion/conclusion

Both microscopic and sub-microscopic P. falciparum infections impair fetoplacental and intrafetal flow, at least temporarily. Increased UA resistance has high specificity but low sensitivity for the detection of placental infection. These findings suggest that interventions to protect the fetus should clear and prevent both microscopic and sub-microscopic malarial infections.

Trial Registration ClinicalTrials.gov NCT01136850. Registered 06 April 2010

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-1689-z) contains supplementary material, which is available to authorized users.

Azithromycin-containing intermittent preventive treatment in pregnancy affects gestational weight gain, an important predictor of birthweight in Papua New Guinea - an exploratory analysis

In Papua New Guinea, intermittent preventive treatment with sulphadoxine-pyrimethamine and azithromycin (SPAZ-IPTp) increased birthweight despite limited impact on malaria and sexually transmitted infections. To explore possible nutrition-related mechanisms, we evaluated associations between gestational weight gain (GWG), enrolment body mass index (BMI) and mid-upper arm circumference (MUAC), and birthweight. We investigated whether the increase in birthweight associated with SPAZ-IPTp may partly be driven by a treatment effect on GWG. The mean GWG rate was 393 g/week (SD 250; n = 948). A 100 g/week increase in GWG was associated with a 14 g (95% CI 2.6, 25.4) increase in birthweight (P = 0.016). Enrolment BMI and MUAC also positively correlated with birthweight. SPAZ-IPTp was associated with increased GWG [58 g/week (26, 900), P < 0.001, n = 948] and with increased birthweight [48 g, 95% CI (8, 880), P = 0.019] when all eligible women were considered (n = 1947). Inclusion of GWG reduced the birthweight coefficient associated with SPAZ-IPTp by 18% from 44 to 36 g (n = 948), although SPAZ-IPTp was not significantly associated with birthweight among women for whom GWG data were available (P = 0.13, n = 948). One month post-partum, fewer women who had received SPAZ-IPTp had a low post-partum BMI (<18.5 kg m(-2) ) [adjusted risk ratio: 0.55 (95% CI 0.36, 0.82), P = 0.004] and their babies had a reduced risk of wasting [risk ratio 0.39 (95% CI 0.21, 0.72), P = 0.003]. SPAZ-IPTp increased GWG, which could explain its impact on birthweight and maternal post-partum BMI. Future trials of SPAZ-IPTp must incorporate detailed anthropometric evaluations to investigate mechanisms of effects on maternal and child health.

Determining effects of areca (betel) nut chewing in a prospective cohort of pregnant women in Madang Province, Papua New Guinea

Background

Chewing areca nut (AN), also known as betel nut, is common in Asia and the South Pacific and the habit has been linked to a number of serious health problems including oral cancer. Use of AN in pregnancy has been associated with a reduction in mean birthweight in some studies, but this association and the relationship between AN chewing and other adverse pregnancy outcomes remain poorly understood.

Methods

We assessed the impact of AN chewing on adverse outcomes including stillbirth, low birthweight (LBW, <2,500 g) and anaemia at delivery (haemoglobin <11.0 g/dL) in a longitudinal cohort of 2,700 pregnant women residing in rural lowland Papua New Guinea (PNG) from November 2009 until February 2013. Chewing habits and participant characteristics were evaluated at first antenatal visit and women were followed until delivery.

Results

83.3 % [2249/2700] of pregnant women used AN, and most chewed on a daily basis (86.2 % [1939/2249]. Smoking and alcohol use was reported by 18.9 % (511/2700) and 5.0 % (135/2688) of women, respectively.

AN use was not associated with pregnancy loss or congenital abnormalities amongst women with a known pregnancy outcome (n = 2215). Analysis of 1769 birthweights did not demonstrate an association between AN and LBW (chewers: 13.7 % [200/1459] vs. non-chewers: 14.5 % [45/310], P = 0.87) or reduced mean birthweight (2957 g vs. 2966 g; P = 0.76). Women using AN were more likely to be anaemic (haemoglobin <11 g/dL) at delivery (75.2 % [998/1314] vs. 63.9 % [182/285], adjusted odds ratio [95 % CI]: 1.67 [1.27, 2.20], P < 0.001). Chewers more commonly had male babies than non-chewers (46.1 % [670/1455] vs. 39.8 % [123/309], P = 0.045).

Conclusions

AN chewing may contribute to anaemia. Although not associated with other adverse pregnancy outcome in this cohort gestational AN use should be discouraged, given the potential adverse effects on haemoglobin and well-established long-term health risk including oral cancer. Future research evaluating the potential association of AN use and anaemia may be warranted.

Trial registration

ClinicalTrials.gov NCT01136850 (06 April 2010).

Preterm or not--an evaluation of estimates of gestational age in a cohort of women from Rural Papua New Guinea

BACKGROUND

Knowledge of accurate gestational age is required for comprehensive pregnancy care and is an essential component of research evaluating causes of preterm birth. In industrialised countries gestational age is determined with the help of fetal biometry in early pregnancy. Lack of ultrasound and late presentation to antenatal clinic limits this practice in low-resource settings. Instead, clinical estimators of gestational age are used, but their accuracy remains a matter of debate.

METHODS

In a cohort of 688 singleton pregnancies from rural Papua New Guinea, delivery gestational age was calculated from Ballard score, last menstrual period, symphysis-pubis fundal height at first visit and quickening as well as mid- and late pregnancy fetal biometry. Published models using sequential fundal height measurements and corrected last menstrual period to estimate gestational age were also tested. Novel linear models that combined clinical measurements for gestational age estimation were developed. Predictions were compared with the reference early pregnancy ultrasound (<25 gestational weeks) using correlation, regression and Bland-Altman analyses and ranked for their capability to predict preterm birth using the harmonic mean of recall and precision (F-measure).

RESULTS

Average bias between reference ultrasound and clinical methods ranged from 0-11 days (95% confidence levels: 14-42 days). Preterm birth was best predicted by mid-pregnancy ultrasound (F-measure: 0.72), and neuromuscular Ballard score provided the least reliable preterm birth prediction (F-measure: 0.17). The best clinical methods to predict gestational age and preterm birth were last menstrual period and fundal height (F-measures 0.35). A linear model combining both measures improved prediction of preterm birth (F-measure: 0.58).

CONCLUSIONS

Estimation of gestational age without ultrasound is prone to significant error. In the absence of ultrasound facilities, last menstrual period and fundal height are among the more reliable clinical measures. This study underlines the importance of strengthening ultrasound facilities and developing novel ways to estimate gestational age.

Knowledge, attitudes, and practices concerning malaria in pregnancy: results from a qualitative study in Madang, Papua New Guinea

Background

Malaria is the leading cause of illness and death in Papua New Guinea (PNG). Infection during pregnancy with falciparum or vivax malaria, as occurs in PNG, has health implications for mother and child, causing complications such as maternal anemia, low birth weight and miscarriage. This article explores knowledge, attitudes and practices concerning malaria during pregnancy and it’s prevention in Madang, PNG, a high prevalence area.

Methods

As part of a qualitative study in Madang, exploring MiP, participatory techniques (free-listing and sorting) were conducted along with focus group discussions, in-depth interviews (with pregnant women, health staff and other community members) and observations in the local community and health facilities.

Results

The main themes explored were attitudes towards and knowledge of MiP, its risks, and prevention. Although there was a general awareness of the term “malaria”, it was often conflated with general sickness or with pregnancy-related symptoms. Moreover, many preventive methods for MiP were related to practices of general healthy living. Indeed, varied messages from health staff about the risks of MiP were observed. In addition to ideas about the seriousness and risk of MiP, other factors influenced the uptake of interventions: availability and perceived comfort of sleeping under insecticide-treated mosquito nets were important determinants of usage, and women’s heavy workload influenced Chloroquine adherence.

Conclusion

The non-specific symptoms of MiP and its resultant conflation with symptoms of pregnancy that are perceived as normal have implications for MiP prevention and control. However, in Madang, PNG, this was compounded by the inadequacy of health staff’s message about MiP.

Risk factors for malaria and adverse birth outcomes in a prospective cohort of pregnant women resident in a high malaria transmission area of Papua New Guinea

BACKGROUND

Low birth weight (LBW), anaemia and malaria are common in Papua New Guinean women.

METHODS

To identify risk factors for LBW, anaemia and preterm delivery (PTD), pregnant women recruited into a cohort study in Madang, Papua New Guinea, were followed to delivery.

RESULTS

Of 470 women enrolled, delivery data were available for 328 (69.7%). By microscopy, 34.4% (113/328) of women had malaria parasitaemia at enrolment and 12.5% (41/328) at delivery; at each time point, PCR detected sub-microscopic parasitaemia in substantially more. Most infections were with Plasmodium falciparum; the remainder being predominantly P. vivax. Anaemia and smoking were associated with lower birth weight, and LBW (16.7%; 51/305) and PTD (21.8%; 63/290) were common. Histopathologically diagnosed chronic placental malaria was associated with LBW (adjusted odds ratio [aOR] 3.3; p=0.048) and PTD (aOR 4.2; p=0.01). Lack of maternal education predisposed to PTD. Sub-microscopic parasitaemia at delivery appeared to increase the risk of LBW. Of the genetic polymorphisms, Southeast Asian ovalocytosis, α(+)-thalassaemia and complement receptor 1 (CR1) deficiency, a CR1 heterozygous genotype was associated with decreased risk of anaemia and substantial but non-significant effects were noted in other comparisons.

CONCLUSIONS

In coastal Papua New Guinea, malaria and anaemia are important causes of adverse pregnancy outcomes.

The associations of parity and maternal age with small-for-gestational-age, preterm, and neonatal and infant mortality: a meta-analysis

Background

Previous studies have reported on adverse neonatal outcomes associated with parity and maternal age. Many of these studies have relied on cross-sectional data, from which drawing causal inference is complex. We explore the associations between parity/maternal age and adverse neonatal outcomes using data from cohort studies conducted in low- and middle-income countries (LMIC).

Methods

Data from 14 cohort studies were included. Parity (nulliparous, parity 1-2, parity ≥3) and maternal age (<18 years, 18-<35 years, ≥35 years) categories were matched with each other to create exposure categories, with those who are parity 1-2 and age 18-<35 years as the reference. Outcomes included small-for-gestational-age (SGA), preterm, neonatal and infant mortality. Adjusted odds ratios (aOR) were calculated per study and meta-analyzed.

Results

Nulliparous, age <18 year women, compared with women who were parity 1-2 and age 18-<35 years had the highest odds of SGA (pooled adjusted OR: 1.80), preterm (pooled aOR: 1.52), neonatal mortality (pooled aOR: 2.07), and infant mortality (pooled aOR: 1.49). Increased odds were also noted for SGA and neonatal mortality for nulliparous/age 18-<35 years, preterm, neonatal, and infant mortality for parity ≥3/age 18-<35 years, and preterm and neonatal mortality for parity ≥3/≥35 years.

Conclusions

Nulliparous women <18 years of age have the highest odds of adverse neonatal outcomes. Family planning has traditionally been the least successful in addressing young age as a risk factor; a renewed focus must be placed on finding effective interventions that delay age at first birth. Higher odds of adverse outcomes are also seen among parity ≥3 / age ≥35 mothers, suggesting that reproductive health interventions need to address the entirety of a woman’s reproductive period.

Funding

Funding was provided by the Bill & Melinda Gates Foundation (810-2054) by a grant to the US Fund for UNICEF to support the activities of the Child Health Epidemiology Reference Group.

Neonatal morbidity and mortality in a Tanzanian tertiary care referral hospital

In developing countries, neonatal mortality accounts for 50-70% of infant mortality. The purpose of this study was to describe morbidity and mortality patterns, with a focus on neonatal infections, in a Tanzanian special care baby unit (SCBU). During a 3-month period, 246 consecutive admissions to the SCBU at Kilimanjaro Christian Medical Centre were audited. Prematurity, low birthweight and suspected infection accounted for 61% of all admissions. The overall mortality rate was 19%, but varied considerably according to gestational age, birthweight and diagnosis. Thirty-one neonates (two-thirds of all deaths) died during the 1st 24 hours of life. Of 27 infants admitted on grounds of perinatal asphyxia, 11 (41%) died, and, of 19 infants with a gestational age <31 weeks, 13 (68%) died. More than two-thirds of all infants were treated with antibiotics. Septicaemia confirmed by blood culture was found in 16 cases. The susceptibility pattern of bacterial isolates did not indicate high rates of resistance to commonly used antibacterial agents. A reduction in the number of preterm deliveries and improved perinatal care to avoid and treat perinatal asphyxia would be the two most important measures in reducing neonatal mortality in this setting.

Malaria in pregnancy: diagnosing infection and identifying fetal risk

Despite increased malaria control efforts, recent reports indicate that over 1.2 million deaths due to malaria occurred in 2010. Pregnant women represent a particularly vulnerable risk group as malaria infection can lead to life-threatening disease for the mother and fetus. With 125 million women at risk of malaria in pregnancy every year, better diagnostic tools are needed for timely identification and treatment of malaria infection. Diagnostic surveillance tools are also needed to estimate disease burden and inform public health policies. In this review, the authors focus on malaria diagnostics in pregnancy and discuss considerations for different Plasmodium species and geographic regions. The authors also look at promising diagnostic modalities to monitor fetal and maternal health in pregnancy and discuss implementation barriers for low resource settings.

The role of prophylactic antimalarial in the reduction of placental parasitemia among pregnant women in Calabar, Nigeria

Introduction:

Intermittent preventive treatment of malaria with sulfadoxine-pyrimethamine is a recommendation of the World Health Organization as part of the malaria control strategy in pregnancy in areas with malaria burden.

Aim:

This study set out to appraise the effectiveness of this regimen in the prevention of placental parasitemia among parturients in Calabar, Nigeria.

Materials and Methods:

Pretested, precoded questionnaires were administered to eligible women at the antenatal clinic and later updated at the labor ward. Intermittent preventive treatment was administered under direct observation at the clinic, while packed cell volume, placental parasitemia, and other laboratory tests were measured at the labor ward.

Results:

The gross presence of placental malaria in the intermittent preventive treatment (IPT)-treated and the control groups was 10.6% and 11.3% respectively (P=0.76). Anemia occurred in 3.1% of the IPT-treated group compared to 11.7% among the control group (P=0.000). Only 7.9% of the IPT-treated women had moderate to severe placental parsitemia whereas as many as 53.2% of women in the control group had moderate to severe parasitemia (P=0.000).

Conclusion:

Intermittent preventive treatment of malaria with sulfadoxine-pyrimethamine was associated with significant reduction in the degree of placental parasitemia among women in the IPT-treated group, although it did not completely eradicate placental malaria in the treatment group.

Research challenges and gaps in malaria knowledge in Papua New Guinea

Taking into consideration the relative number of people living in Papua New Guinea the burden of malaria in this country is among the highest in Asia and the Pacific region. This article summarizes the research questions and challenges being undertaken by the Southwest Pacific International Center of Excellence for Malaria Research in the context of the epidemiology, transmission and pathogenesis of Plasmodium falciparum and P. vivax at the present time and the recent past. It is hoped that the research accomplished and local infrastructure strengthened by this effort will help inform regional and national policy with regard to the control and ultimately elimination of malaria in this region of the world.

Malaria in pregnancy in the Asia-Pacific region

Most pregnant women at risk of for infection with Plasmodium vivax live in the Asia-Pacific region. However, malaria in pregnancy is not recognised as a priority by many governments, policy makers, and donors in this region. Robust data for the true burden of malaria throughout pregnancy are scarce. Nevertheless, when women have little immunity, each infection is potentially fatal to the mother, fetus, or both. WHO recommendations for the control of malaria in pregnancy are largely based on the situation in Africa, but strategies in the Asia-Pacific region are complicated by heterogeneous transmission settings, coexistence of multidrug-resistant Plasmodium falciparum and Plasmodium vivax parasites, and different vectors. Most knowledge of the epidemiology, effect, treatment, and prevention of malaria in pregnancy in the Asia-Pacific region comes from India, Papua New Guinea, and Thailand. Improved estimates of the morbidity and mortality of malaria in pregnancy are urgently needed. When malaria in pregnancy cannot be prevented, accurate diagnosis and prompt treatment are needed to avert dangerous symptomatic disease and to reduce effects on fetuses.

Nutritional status of Makushi Amerindian children and adolescents of Guyana

BACKGROUND

Amazonian Indians are in the midst of a rapid cultural transition. The developments affecting Amazonian Indians present an opportunity to address important public health problems through public and private initiatives, but to do so it is imperative to begin with information on the health status of these peoples and the underlying factors affecting it. However, relatively few such data are available for this vast region.

AIM

This study describes the nutritional status of Makushi Amerindians of Guyana and considers several variables which might help to explain it.

SUBJECTS AND METHODS

Data for 792 Makushi, 0-20 years of age from 11 villages are considered. Outcome variables considered are anthropometric markers of growth and nutritional status; specifically height-for-age, weight-for-height and body-mass index. Predictor variables explored are age, sex, relative isolation, number of siblings, season of birth, diet and morbidity. Fisher's exact test, chi-square, Pearson's correlation and multiple regression were used to assess possible relationships between these variables.

RESULTS

Relative to other Amazonian Indians, the Makushi have a lower rate of linear-growth faltering and a higher rate of linear-growth faltering relative to non-Amerindian Guyanese. Males, older cohorts, those living in isolated villages or born in the wet season showed higher rates of growth faltering.

CONCLUSION

Makushi nutritional status may be explained by sex, age, relative isolation, family size, season of birth, dietary intake and infectious disease.

Induction of hyperglycemia in adult intrauterine growth-restricted rats: effects on renal function

Intrauterine growth restriction (IUGR) leads to a reduction in nephron endowment at birth and is linked to renal dysfunction in adulthood. The aim of the present study was to determine whether kidneys of IUGR rat offspring are more vulnerable to a secondary insult of hyperglycemia. IUGR was induced in Wistar-Kyoto rats by maternal protein restriction. At 24 wk of age, diabetes was induced in male IUGR and non-IUGR offspring by streptozotocin injection; insulin was injected daily to maintain blood glucose levels at either a mild (7-10 mmol/l; n=8/group) or a moderate (10-15 mmol/l; n=8/group) level. At 32 wk of age, renal function was assessed using ultrasound and [(3)H]inulin and [(14)C]para-aminohippurate clearance techniques. Conscious mean arterial blood pressure and heart rate were unchanged in IUGR offspring. Relative kidney length was increased significantly in IUGR offspring, and renal function was altered significantly; of importance, there was a significant increase in filtration fraction, indicative of glomerular hyperfiltration. Induction of hyperglycemia led to marked impairment of renal function. However, the response to hyperglycemia was not different between IUGR and non-IUGR offspring. Maintaining blood glucose levels at a mild hyperglycemic level led to marked improvement in all measures of renal function in IUGR and non-IUGR offspring. In conclusion, while the IUGR offspring showed evidence of hyperfiltration, the response to hyperglycemia was similar in IUGR and non-IUGR kidneys in adulthood. Importantly, maintaining blood glucose levels at a mild hyperglycemic level markedly attenuated the renal dysfunction associated with diabetes, even in IUGR offspring.

Folate metabolism pathway and Plasmodium falciparum malaria infection in pregnancy

Malaria induced by Plasmodium falciparum is a major cause of mortality. P. falciparum has the ability to use host plasma folate as its primary folate source. Folate is a cofactor needed for both malaria parasite growth and host erythrocyte production. This review examines the possible impairment of the folate-mediated one-carbon metabolism pathway as a result of P. falciparum malaria infection during pregnancy. Folate deficiency during malaria infection is presented, with an emphasis on the controversy regarding the decrease of plasma or erythrocyte folate secondary to malaria. Maternal folate deficiency increases the risk of adverse pregnancy outcomes. Functional folate deficiency and/or increased plasma homocysteine levels during pregnancy of infected women in areas endemic for malaria is a probable scenario accentuating the impairment of placenta function leading to the occurrence of neural tube defects, low birth weights, and intrauterine growth retardations. Potential questions that may be answered in future investigations using an appropriate protocol to study pregnant women with malaria are also addressed.

Pharmacokinetic properties of conventional and double-dose sulfadoxine-pyrimethamine given as intermittent preventive treatment in infancy

Intermittent preventive treatment in infancy (IPTi) entails routine administration of antimalarial treatment doses at specified times in at-risk infants. Sulfadoxine-pyrimethamine (SDX/PYR) is a combination that has been used as first-line IPTi. Because of limited pharmacokinetic data and suggestions that higher milligram/kilogram pediatric doses than recommended should be considered, we assessed SDX/PYR disposition, randomized to conventional (25/1.25 mg/kg of body weight) or double (50/2.5 mg/kg) dose, in 70 Papua New Guinean children aged 2 to 13 months. Blood samples were drawn at baseline, 28 days, and three time points randomly selected for each infant at 4 to 8 h or 2, 5, 7, 14, or 21 days. Plasma SDX, PYR, and N(4)-acetylsulfadoxine (NSX, the principal metabolite of SDX) were assayed by high-performance liquid chromatography (HPLC). Using population modeling incorporating hepatic maturation and cystatin C-based renal function, two-compartment models provided best fits for PYR and SDX/NSX plasma concentration profiles. The area under the plasma concentration-time curve from 0 h to infinity (AUC(0-∞)) was greater with the double dose versus the conventional dose of PYR (4,915 versus 2,844 μg/day/liter) and SDX (2,434 versus 1,460 mg/day/liter). There was a 32% reduction in SDX relative bioavailability with the double dose but no evidence of dose-dependent metabolism. Terminal elimination half-lives (15.6 days for PYR, 9.1 days for SDX) were longer than previously reported. Both doses were well tolerated without changes in hemoglobin or hepatorenal function. Five children in the conventional and three in the double-dose group developed malaria during follow-up. These data support the potential use of double-dose SDX/PYR in infancy, but further studies should examine the influence of hepatorenal maturation in very young infants.

Global report on preterm birth and stillbirth (2 of 7): discovery science

Background

Normal and abnormal processes of pregnancy and childbirth are poorly understood. This second article in a global report explains what is known about the etiologies of preterm births and stillbirths and identifies critical gaps in knowledge. Two important concepts emerge: the continuum of pregnancy, beginning at implantation and ending with uterine involution following birth; and the multifactorial etiologies of preterm birth and stillbirth. Improved tools and data will enable discovery scientists to identify causal pathways and cost-effective interventions.

Pregnancy and parturition continuum

The biological process of pregnancy and childbirth begins with implantation and, after birth, ends with the return of the uterus to its previous state. The majority of pregnancy is characterized by rapid uterine and fetal growth without contractions. Yet most research has addressed only uterine stimulation (labor) that accounts for <0.5% of pregnancy.

Etiologies

The etiologies of preterm birth and stillbirth differ by gestational age, genetics, and environmental factors. Approximately 30% of all preterm births are indicated for either maternal or fetal complications, such as maternal illness or fetal growth restriction. Commonly recognized pathways leading to preterm birth occur most often during the gestational ages indicated: (1) inflammation caused by infection (22-32 weeks); (2) decidual hemorrhage caused by uteroplacental thrombosis (early or late preterm birth); (3) stress (32-36 weeks); and (4) uterine overdistention, often caused by multiple fetuses (32-36 weeks). Other contributors include cervical insufficiency, smoking, and systemic infections. Many stillbirths have similar causes and mechanisms. About two-thirds of late fetal deaths occur during the antepartum period; the other third occur during childbirth. Intrapartum asphyxia is a leading cause of stillbirths in low- and middle-income countries.

Recommendations

Utilizing new systems biology tools, opportunities now exist for researchers to investigate various pathways important to normal and abnormal pregnancies. Improved access to quality data and biological specimens are critical to advancing discovery science. Phenotypes, standardized definitions, and uniform criteria for assessing preterm birth and stillbirth outcomes are other immediate research needs.

Conclusion

Preterm birth and stillbirth have multifactorial etiologies. More resources must be directed toward accelerating our understanding of these complex processes, and identifying upstream and cost-effective solutions that will improve these pregnancy outcomes.

Betel nut chewing during pregnancy, Madang province, Papua New Guinea

INTRODUCTION

In Papua New Guinea, betel nut chewing is very common in the general population and in pregnant women. It has similarities in terms of use and complications of use to chewing tobacco (=smokeless tobacco), as its active agent, arecoline is similar to nicotine. The present study investigates the habits of betel nut chewing and possible impact on pregnancy.

METHODS

In a cross-sectional survey 310 pregnant women attending Alexishafen Health Centre (Madang Province) were interviewed with a survey measuring: detailed demographic data, betel nut chewing habits, other potential addictions (smoking, alcohol and drug use) and a medical examination (weight, height, blood pressure and hemoglobin level were recorded). Their babies have been assessed for birth weight and signs of prematurity.

RESULTS

Among pregnant women, 94% regularly chew betel nut, 9% smoke and 1% used alcohol. 31% are heavy chewers (>10 nuts/day). The principal reasons for pregnant women to chew are: to prevent morning sickness (28%), to prevent having a smelly mouth (26%), the habit of chewing (20%), being addicted (10%). Primigravidity, betel nut chewing and low BMI had a statistically significant impact on birth weight reduction of 467 g (p<0.001), 238 g (p=0.02) and 175 g (p=0.005) respectively. 80% of the women thought that chewing would not have any effect on the fetus.

DISCUSSION

Given the high use of "pure" betel nut among pregnant women, a significant impact on birth weight reduction and a poor knowledge about the adverse health effects of this substance, prevention programs in pregnant women should include betel nut chewing as a risk factor for poor pregnancy outcome.

Alpha+ -thalassaemia and pregnancy in a malaria endemic region of Papua New Guinea

The effect of maternal alpha+ -thalassaemia on pregnancy was assessed in the north coastal region of Papua New Guinea (PNG), where malaria is hyperendemic and alpha+ -thalassaemia is extremely common. In a prospective study of 987 singleton hospital deliveries, we correlated maternal alpha-globin genotype with markers of reproductive fitness (age in primigravidae, gravidity, pregnancy interval and the number of miscarriages and stillbirths), Plasmodium falciparum(P. falciparum) infection of the mother and placenta, maternal haemoglobin, preterm delivery and birthweight. The frequency of the -alpha genotype in mothers was 0.61. Markers of reproductive fitness were similar in women with and without alpha+ -thalassaemia. Median haemoglobin concentration during pregnancy and after delivery was about 1.0 g/dl lower in homozygous alpha+ -thalassaemia than in women with a normal alpha- globin genotype (P < or = 0.001). The frequency of placental P. falciparum infection and systemic malaria infection after delivery showed no consistent relationship to alpha-globin genotype. The frequency of preterm delivery and low birthweight did not vary significantly according to maternal alpha-globin genotype. Maternal alpha+ -thalassaemia does not affect reproductive fitness or susceptibility to malaria during pregnancy. Although median haemoglobin concentration was significantly lower in mothers homozygous for alpha+ -thalassaemia than those with a normal alpha-globin genotype, this did not result in an adverse outcome of pregnancy.

The epidemiology of preterm labor--a global perspective

The major burden of preterm birth is in the developing world, where much of the death and morbidity is secondary to infectious diseases such as malaria, HIV, tuberculosis and intestinal parasites. There is some evidence to support the concept that normal gestational length varies with ethnic group; babies of black African ancestry tend to be born earlier, more commonly pass meconium in labor, but have less respiratory distress than white European babies of matched gestational age. However, ethnic differences are tiny compared with the effects of infectious disease and malnutrition. Interventions to prevent preterm birth should predominantly be aimed at the prevention and treatment of infectious disease, and the improvement of maternal nutrition. Without this, medical intervention tends to increase the rate of preterm birth without corresponding improvement in outcomes.

Risk factors and mechanisms of preterm delivery in Malawi

PROBLEM

We examined risk factors and mechanisms of preterm delivery (PTD) in malaria-exposed pregnant women in Blantyre, Malawi.

METHOD OF STUDY

The human immunodeficiency virus (HIV), malaria, syphilis, and anemia were assessed in a cross-sectional study of 572 pregnant women. In a nested case-control study, chorioamnionitis (CAM) was examined; tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-8, macrophage inflammatory protein (MIP)-1alpha, monocyte chemotactic protein (MCP)-1, transforming growth factor (TGF)-beta, cortisol, and corticotropin-releasing hormone were measured in placental, maternal and/or cord blood.

RESULTS

HIV, infrequent antenatal clinic attendance, low-maternal weight, no intermittent preventive malaria therapy (IPT), and CAM were associated with PTD, while malaria was not. Of the 18 compartmental cytokine measurements, elevations in placental and/or cord IL-6 and IL-8 were associated with both CAM and PTD. In contrast, there was no overlap between the cytokines affected by malaria and those associated with PTD.

CONCLUSIONS

The HIV and CAM were the major infections associated with PTD in this study. CAM, but not malaria, causes PTD via its effect on proinflammatory cytokines.

The epidemiology of malaria in Papua New Guinea

Papua New Guinea (PNG) is a patchwork of different ecological zones, inhabited by human populations of exceptional cultural and linguistic diversity. This results in complex variations in vector ecology and malaria epidemiology. Malaria is the main cause of morbidity in many health facilities in lowland areas, but it is absent in much of the highlands. All four human malaria species occur, but endemicity varies widely, with Plasmodium falciparum locally reaching holo-endemic levels that are rarely found outside sub-Saharan Africa. The high frequency of Plasmodium vivax is an important difference to most African situations. PNG is therefore a prime location for studies of interactions between different parasite species, and of the biology of local human genetic adaptation and its implications for malaria morbidity and mortality.

Is There a Causal Relationship between Iron Deficiency or Iron-Deficiency Anemia and Weight at Birth, Length of Gestation and Perinatal Mortality?

An extensive literature review was conducted to identify whether iron deficiency, iron-deficiency anemia and anemia from any cause are causally related to low birth weight, preterm birth or perinatal mortality. Strong evidence exists for an association between maternal hemoglobin concentration and birth weight as well as between maternal hemoglobin concentration and preterm birth. It was not possible to determine how much of this association is attributable to iron-deficiency anemia in particular. Minimal values for both low birth weight and preterm birth occurred at maternal hemoglobin concentrations below the current cut-off value for anemia during pregnancy (110 g/L) in a number of studies, particularly those in which maternal hemoglobin values were not controlled for the duration of gestation. Supplementation of anemic or nonanemic pregnant women with iron, folic acid or both does not appear to increase either birth weight or the duration of gestation. However, these studies must be interpreted cautiously because most are subject to a bias toward false-negative findings. Thus, although there may be other reasons to offer women supplemental iron during pregnancy, the currently available evidence from studies with designs appropriate to establish a causal relationship is insufficient to support or reject this practice for the specific purposes of raising birth weight or lowering the rate of preterm birth.