***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Spatial analyses of the effect of insecticide (permethrin)-treated bed nets ( ITNs ) on nearby households both with and without ITNs was performed in the context of a large-scale , group-r and omized , controlled mortality trial in Asembo , western Kenya . Results illustrate a protective effect of ITNs on compounds lacking ITNs located within 300 meters of compounds with ITNs for child mortality , moderate anemia , high-density parasitemia , and hemoglobin levels . This community effect on nearby compounds without nets is approximately as strong as the effect observed within villages with ITNs . This implies that in areas with intense malaria transmission with high ITN coverage , the primary effect of insecticide-treated nets is via area-wide effects on the mosquito population and not , as commonly supposed , by simple imposition of a physical barrier protecting individuals from biting . The strength of the community effect depended upon the proportion of nearby compounds with treated nets . To maximize their public health impact , high coverage with treated nets is essential The effectiveness of insecticide-treated bednets ( ITBN ) in preventing malaria and anaemia among primigravidae living in Kilifi District , Kenya , was assessed by a r and omized controlled trial between September 1994 and November 1995 . All residents within 28 community clusters received ITBN in July 1993 , whilst residents of another 28 clusters served as contemporaneous controls . All resident primigravid women with singleton pregnancies attending antenatal care at Kilifi District Hospital were eligible for recruitment . 503 primigravidae were recruited . 91.4 % were anaemic antenatally ( Hb < 11 g/dl ) : 91.0 % from the intervention arm and 92.0 % from the control arm . Severe anaemia ( Hb < 7 g/dl ) was found among 15.1 % of intervention women and 20.1 % of control women ( P = 0.28 ) . No significant differences were observed in reports of febrile illness or the presence of chloroquine in the serum or peripheral parasitaemia during the third trimester between the two groups . In the women delivering in hospital ( n = 130 ) , there was no association between placental malaria infection and the intervention : 77.4 % of placentas from control women had evidence of past or active infection , compared with 72.0 % of placentas from intervention women ( P = 0.76 ) . Similarly , in the women delivering in hospital , ITBN did not improve birth weight , and there were no differences in perinatal mortality between the two study groups . Despite ITBN having a great impact on paediatric severe malaria and mortality in this transmission setting , there was very little impact of ITBN on the morbidity associated with malaria infection in primigravidae . Alternative strategies are required to tackle this continued public health problem for pregnant women living in endemic areas similar to the Kenyan Coast The impact of insecticide (permethrin)-treated bed nets ( ITNs ) on  malaria in pregnancy was studied in a rural area in western Kenya with intense perennial malaria transmission . All households in 40 of 79 villages were r and omized to receive  ITNs  by January 1997 . The ITNs were distributed in control villages two years later . Complete data on birth outcome were available on 2,754 ( 89.6 % ) of 3,072 deliveries . Women ( n = 780 ) were followed monthly throughout pregnancy in 19 of 79 villages . Among gravidae 1 - 4 , ITNs were associated with reductions of 38 % ( 95 % confidence interval [ CI ] = 17 - 54 % ) in the incidence of malaria parasitemia and 47 % ( 95 % CI = 6 - 71 % ) in the incidence of severe malarial anemia ( hemoglobin level < 8 g/dL with parasitemia ) during pregnancy . At the time of delivery , mean hemoglobin levels were 0.6 g/dL ( 95 % CI = 0.01 - 1.2 g/dL ) higher , the prevalence of placental or maternal malaria was reduced by 35 % ( 95 % CI = 20 - 47 % ) , and the prevalence of low birth weight was reduced by 28 % ( 95 % CI = 2 - 47 % ) in gravidae 1 - 4 from ITN villages . No beneficial impact was observed in gravidae five or higher . In areas of intense perennial malaria transmission , permethrin-treated bed nets reduce the adverse effect of malaria during the first four pregnancies As part of a community-based , group-r and omized , controlled trial of insecticide-treated bed nets ( ITNs ) in an area with intense malaria transmission in western Kenya , a birth cohort ( n = 833 ) was followed monthly until the age of 24 months to determine the potential beneficial and adverse effects of reduced malaria exposure during pregnancy and infancy . Malaria transmission and morbidity were comparable pre-intervention . The ITNs reduced malaria attack rates ( force of infection ) in infancy by 74 % , and delayed the median time-to-first parasitemia ( 4.5 to 10.7 months ; P < 0.0001 ) . The incidence of both clinical malaria and moderate-severe anemia ( hemoglobin level < 7 g/dL ) were reduced by 60 % ( P < 0.001 for both ) . Protective efficacy was greatest in infants less than three months old and similar in older infants and one-year-old children . Efficacy was lowest in the dry season . Infants from ITN villages experienced better height and weight gain . In areas of intense perennial malaria transmission , ITNs substantially reduce exposure to malaria and subsequent malaria-associated morbidity in children less than 24 months old . Reduced malaria exposure during infancy did not result , with continued ITN use , in increased malaria morbidity in one-year-old children A prospect i ve comparison of the antimalarial efficacy of bed nets was conducted with 341 pregnant women living in a mesoendemic malarious area of the Thai-Burmese border . Women in 3 adjacent study sites were allocated at r and om to receive either a single size permethrin-impregnated bed net ( PIB ) , a non-impregnated bed net ( NIB ) , or to a control group who used either their own family size non-impregnated bed net ( FNIB ) or no net . In one study site , but not the other 2 , PIB significantly reduced parasite densities and , together with FNIB , reduced the incidence of malaria in pregnancy from 56 % to 33 % ( relative risk = 1.67 , confidence interval = 1.07 - 2.61 , P = 0.03 , allowing for parity ) . Anaemia proved a more sensitive marker of bed net antimalarial efficacy than parasite rates . The incidence of anaemia ( haematocrit < 30 % ) at all study sites was significantly lower at delivery in the PIB ( 27 % ) and FNIB groups ( 21 % ) than in the NIB group ( 41 % ) or those using no net ( 56 % ) . This suggests that a significant proportion of the malaria in pregnancy in this mesoendemic area was sub-patent . Both patent Plasmodium falciparum parasitaemia and anaemia were associated with a reduction in birth weight . Infant mortality was high ( 16 % ) and strongly associated with prematurity , low birth weight and maternal anaemia . PIB were well tolerated and had no apparent adverse effect on the pregnancy or infant development . Although the overall effect of bed nets on patent parasitaemia was marginal , they were associated with a significant reduction in maternal malaria-associated anaemia . ( ABSTRACT TRUNCATED AT 250 WORDS To compare the effects of intermittent treatment with sulfadoxine-pyrimethamine ( SP ) given during the second and third trimester of pregnancy , the use of insecticide-treated nets ( ITN ) , or the combination of both on haemoglobin ( Hb ) levels during pregnancy , a r and omized , placebo-controlled intervention trial was conducted in a malaria-endemic area of western Kenya from July 1997 to September 1999 . Primigravidae and secundigravidae were enrolled into the study and r and omized into 4 intervention groups : ( i ) ITNs and SP , ( ii ) ITNs and placebo SP , ( iii ) SP alone , and ( iv ) placebo SP . All groups were offered case management and iron and folic acid supplementation .  Seven hundred and fifty-two women were followed until delivery ( 53.2 % were primigravidae and 46.8 % secundigravidae ) . Among primigravidae in all the groups there was a significant improvement in Hb levels at delivery ( 107.6 g/L ) compared with recruitment ( 101.9 g/L ) ( P < 0.006 ) with the greatest improvement in the combination ITNs + SP group . The protective efficacy of ITNs + SP on anaemia was 55.8 % ( 95 % CI 30.6 - 71.8 ) , of SP alone 50.9 % ( 95 % CI 22.2 - 69.0 ) , and of ITNs 41.6 % ( 95 % CI 9.8 - 62.3 ) . Among secundigravidae , Hb levels were slightly lower at delivery compared with recruitment ( P = 0.03 ) . It was concluded that malaria is a major cause of anaemia in primigravidae but that other causes play a more significant role in secundigravidae , and that intermittent treatment with SP or use of ITNs benefits primigravidae more than secundigravidae Effects of the distribution in space of permethrin (insecticide)-impregnated bed nets ( IIBNS ) on  child mortality  were studied in a r and omized controlled trial of IIBNs in a an area highly endemic for Plasmodium falciparum malaria in rural northern Ghana . Eight hundred sixty-two deaths occurred among children 6 - 59 months of age during 16,841 child-years-at-risk .  Mortality increased with the distance from health facilities but not with proximity to identifiable anopheline breeding sites ( reservoirs ) . The efficacy of IIBNs was independent of these distances . Mortality in users of IIBNs was independent of the proximity of nonusers , and mortality rates of nonusers and users living close to each other were similar . Poisson regression estimated a 6.7 % increase in mortality among nonusers with each 100-m shift away from the nearest compound with IIBNS , indicating that the insecticide protects nearby nonusers . High coverage of IIBNs achieves maximum impact , but users of IIBNs offer some protection to less fortunate neighbors if coverage is incomplete The impact of insecticide-treated bednet use on  malaria and anaemia in pregnancy was assessed , as a supplementary study , in a major WHO/TDR-supported bednet trial in northern Ghana between July 1994 and April 1995 . The study area was divided into 96 clusters of compounds , with 48 clusters being r and omly allocated to intervention . All pregnant women were included in the study but the focus was on primigravidae and secundigravidae . 1961 pregnant women were recruited into the study --1033 ( 52.7 % ) in the treated bednet group and 928 ( 47.3 % ) in the no net group . 1806 ( 92.1 % ) had blood taken for malaria microscopy and haemoglobin determination in the third trimester . Pregnancy  outcomes were reported for 847 women . The characteristics of women in intervention and control groups were comparable . The odds ratios , with 95 % confidence interval ( CI ) , for different study endpoints were , for Plasmodium falciparum parasitaemia--0.89 ( 0.73 , 1.08 ) , for anaemia--0.88 ( 0.70 , 1.09 ) , for low birthweight (LBW)--0.87 ( 0.63 , 1.19 ) , indicating no benefit for treated bednet use . Effective net use by parity varied from 42 % in primigravidae to 63 % in multigravidae , in spite of free nets and insecticide impregnation . The main reasons for not using a net were warm weather and perceived absence of mosquito biting . Chloroquine use in pregnancy was low and comparable in both groups . Implication s of findings for malaria control in pregnancy and further research are discussed 
    Output:
    
The trial in Thail and , which r and omised individuals to ITNs or untreated nets , showed reductions in anaemia and fetal loss in all gravidae , but not reductions in clinical malaria or low birth weight .
CONCLUSIONS ITNs used throughout pregnancy or from mid-pregnancy onwards have a beneficial impact on pregnancy outcome in malaria-endemic Africa in the first few pregnancies .