***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: BACKGROUND Results from observational studies suggest that micronutrient status is a determinant of the progression of human immunodeficiency virus ( HIV ) disease . METHODS We enrolled 1078 pregnant women infected with HIV in a double-blind , placebo-controlled trial in Dar es Salaam , Tanzania , to examine the effects of daily supplements of vitamin A ( preformed vitamin A and beta carotene ) , multivitamins ( vitamins B , C , and E ) , or both on progression of HIV disease , using survival  models . The median follow-up with respect to survival was 71 months ( interquartile range , 46 to 80 ) . RESULTS Of 271 women who received multivitamins  , 67 had progression to World Health Organization ( WHO ) stage 4 disease or died -- the primary outcome --as compared with 83 of 267 women who received placebo ( 24.7 percent vs. 31.1 percent ; relative risk , 0.71 ; 95 percent confidence interval , 0.51 to 0.98 ; P=0.04 ) . This regimen was also associated with reductions in the relative risk of death related to the acquired immunodeficiency syndrome ( 0.73 ; 95 percent confidence interval , 0.51 to 1.04 ; P=0.09 ) , progression to WHO stage 4 ( 0.50 ; 95 percent confidence interval , 0.28 to 0.90 ; P=0.02 ) , or progression to stage 3 or higher ( 0.72 ; 95 percent confidence interval , 0.58 to 0.90 ; P=0.003 ) . Multivitamins also result ed in significantly higher CD4 + and CD8 + cell counts and significantly lower viral loads . The effects of receiving vitamin A alone were smaller and for the most part not significantly different from those produced by placebo . Adding vitamin A to the multivitamin regimen reduced the benefit with regard to some of the end points examined . CONCLUSIONS Multivitamin supplements delay the progression of HIV disease and provide an effective , low-cost means of delaying the initiation of antiretroviral therapy in HIV-infected women Objective To determine the risk of HIV transmission by infant feeding modality . Design and setting A prospect i ve study in two hospitals in Durban , South Africa . Participants A total of 551 HIV-infected pregnant women enrolled in a r and omized trial of vitamin A.  Interventions Women self-selected to breastfeed or formula feed after being counselled . Breastfeeders were encouraged to practice exclusive breastfeeding for 3–6 months . Main outcome measures Cumulative probabilities of detecting HIV over time were estimated using Kaplan – Meier methods and were compared in three groups : 157 formula-fed ( never breastfed ) ; 118 exclusively breastfed for 3 months or more ; and 276 mixed breastfed . Results The three feeding groups did not differ in any risk factors for transmission , and the probability of detecting HIV at birth was similar . Cumulative probabilities of HIV detection remained similar among never and exclusive breastfeeders up to 6 months : 0.194 ( 95 % CI 0.136–0.260 ) and 0.194 ( 95 % CI 0.125–0.274 ) , respectively , whereas the probabilities among mixed breastfeeders soon surpassed both groups reaching 0.261 ( 95 % CI 0.205–0.319 ) by 6 months . By 15 months , the cumulative probability of HIV infection remained lower among those who exclusively breastfed for 3 months or more than among other breastfeeders ( 0.247 versus 0.359 ) . Conclusion Infants exclusively breastfed for 3 months or more had no excess risk of HIV infection over 6 months than those never breastfed . These findings , if confirmed elsewhere , can influence public health policies on feeding choices available to HIV-infected mothers in developing countries BACKGROUND Multiple micronutrient deficiencies may contribute to low birth weight , which is a major global determinant of mortality . OBJECTIVE We assessed the effect of prenatal multimicronutrient supplementation on gestational length and birth size . DESIGN We conducted a r and omized , placebo-controlled , double-blind effectiveness trial among antenatal care attendees in Harare , Zimbabwe . Pregnant women ( 22 - 35 wk of gestation ) were r and omly allocated to receive a multimicronutrient or placebo supplement daily until delivery . Supplementation with iron and folic acid was part of antenatal care . RESULTS Of 1669 women , birth data were available from 1106 ( 66 % ) , of whom 360 ( 33 % ) had HIV infection . The mean gestational length was 39.1 wk , and 16.6 % of the women had a gestational length < 37 wk . The mean birth weight was 3030 g , and 10.5 % of the infants had a birth weight < 2500 g. Multimicronutrient supplementation was associated with tendencies for increased gestational length ( 0.3 wk ; 95 % CI : -0.04 , 0.6 wk ; P = 0.06 ) , birth weight ( 49 g ; -6 , 104 g ; P = 0.08 ) , and head circumference ( 0.2 cm ; -0.02 , 0.4 cm ; P = 0.07 ) but was not associated with low birth weight ( birth weight < 2500 g ) ( relative risk : 0.84 ; 0.59 , 1.18 ; P = 0.31 ) . The effect of multimicronutrient supplementation on birth weight was not significantly different between HIV-uninfected ( 26 g ; -38 , 91 g ) and HIV-infected ( 101 g ; -3 , 205 g ) subjects ( interaction , P > 0.10 ) . CONCLUSION Antenatal multimicronutrient supplementation may be one strategy to increase birth size We investigated the effect of supplementing women weekly with 7000 microg retinol equivalents as preformed vitamin A or beta-carotene vs. a placebo , on the incidence of night blindness during pregnancy and the postpartum period in the rural plains of Nepal . Over a period of approximately 3 y , approximately 29,000 women of child-bearing age , living in 171 wards that were r and omized to one of the three supplements , contributed 9932 first pregnancies . A prospect i ve , weekly surveillance identified night blindness in pregnant women , verified further by detailed question ing about nighttime vision . After delivery , women were also interviewed at approximately 3 and approximately 6 mo postpartum to elicit a night blindness history over the preceding 3 mo . Vitamin A supplementation reduced the incidence of night blindness during pregnancy from 10.7 % among controls to 6.7 % ( relative risk 0.62 , 95 % confidence interval : 0.45 - 0.85 ) . beta-Carotene supplementation had less of an effect ( 0 . 83 , 0.63 - 1.11 ) . Among women who took > 95 % of their vitamin A supplements during pregnancy , incidence of verified night blindness was reduced by 67 % . Incidence ( per 100 person-years ) of night blindness during the first 3 mo postpartum was 11.3 in the control , 4.3 in the vitamin A and 8.7 in the beta-carotene groups , yielding corresponding relative risks of 0.38 ( 0.26 - 0.55 ) and 0.77 ( 0.57 - 1 . 04 ) . In the second 3 mo postpartum , both vitamin A and beta-carotene reduced night blindness by approximately 50 % . Vitamin A intakes approaching a recommended amount for pregnancy markedly reduced but did not eliminate night blindness in Nepali women . Greater intakes of vitamin A than provided and /or other nutrients may be needed to prevent maternal  night blindness in rural South Asia BACKGROUND Young infants are at risk of vitamin A deficiency . Supplementation of breastfeeding mothers improves the vitamin A status of their infants , but there are no data regarding its effect on infant mortality , and data on the effect of directly supplementing infants during the first few weeks of life are conflicting . OBJECTIVE The objective was to measure the effect on infant mortality of supplementing neonates and their HIV-negative mothers with single , large doses of vitamin A during the immediate postpartum period . DESIGN A r and omized , placebo-controlled , 2-by-2 factorial design trial was conducted in 14,110 mothers and their infants ; 9208 of the mothers were HIV-negative at delivery , remained such during the postpartum year , and were retained in the current analysis . The infants were r and omly assigned within 96 h of delivery to 1 of 4 treatment groups : mothers and infants received vitamin A ( Aa ) , mothers received vitamin A and infants received placebo ( Ap ) , mothers received placebo and infants received vitamin A ( Pa ) , and both mothers and infants received placebo ( Pp ) . The vitamin A dose in the mothers was 400,000 IU and in the infants was 50,000 IU . The mother-infant pairs were followed to 12 mo . RESULTS Hazard ratios ( 95 % CI ) for 12 mo mortality among infants in the maternal-supplemented and infant-supplemented groups were 1.17 ( 0.87 , 1.58 ) and 1.08 ( 0.80 , 1.46 ) , respectively . Hazard ratios ( 95 % CI ) for the Aa , Ap , and Pa groups compared with the Pp group were 1.28 ( 0.83 , 1.98 ) , 1.27 ( 0.82 , 1.97 ) , and 1.18 ( 0.76 , 1.83 ) , respectively . These data indicate no overall effect . Serum retinol concentrations among a sub sample of women were similar to reference norms . CONCLUSION Postpartum maternal or neonatal vitamin A supplementation may not reduce infant mortality in infants of HIV-negative women with an apparently adequate vitamin A status BACKGROUND Linear growth retardation and wasting are common in children born to HIV-infected women . Inexpensive interventions that could improve the postnatal growth pattern of such children are needed . OBJECTIVE The objective was to examine the effect of supplementing HIV-infected women with multivitamins or vitamin A and beta-carotene , during and after pregnancy , on the growth of their children during the first 2 y of life . DESIGN We conducted a r and omized placebo-controlled trial in 886 mother-infant pairs in Tanzania . At the first prenatal visit , HIV-infected women were r and omly assigned to 1 of 4 daily oral regimens in a 2 x 2 factorial fashion : multivitamins ( MV : thiamine , riboflavin , vitamin B-6 , niacin , vitamin B-12 , vitamin C , vitamin E , and folic acid ) , preformed vitamin A + beta-carotene ( VA/BC ) , MV including VA/BC , or placebo . Supplementation continued during the first 2 y postpartum and thereafter . Children were weighed and measured monthly , and all received vitamin A supplements after 6 mo of age per the st and ard of care . RESULTS Multivitamins had a significant positive effect on attained weight ( 459 g ; 95 % CI : 35 , 882 ; P = 0.03 ) and on weight-for-age ( 0.42 ; 95 % CI : 0.07 , 0.77 ; P = 0.02 ) and weight-for-length ( 0.38 ; 95 % CI : 0.07 , 0.68 ; P = 0.01 ) z scores at 24 mo . VA/BC seemed to reduce the benefits of MV on these outcomes . No significant effects were observed on length , midupper arm circumference , or head circumference . CONCLUSION Supplementation of HIV-infected women with multivitamins ( vitamin B complex , vitamin C , and vitamin E ) during pregnancy and lactation is an effective intervention for improving ponderal growth in children Night blindness occurs commonly among women during pregnancy in rural NEPAL : We examined the relationship between maternal night blindness and the risk of mortality occurring among infants in the first 6 mo of life . Stratified analysis by maternal night blindness status during pregnancy was done for 10,000 women participating in a r and omized , placebo-controlled trial of vitamin A and beta-carotene supplementation .  Mortality of infants of non-night blind women in all three supplementation groups was similar , and when combined , was 63/1000 live births . Relative to this , mortality was higher by 63 % [ 95 % confidence interval ( CI ) : 9 - 138 % ) and 50 % ( 95 % CI : -3 to 133 % ) among infants of night blind women receiving placebo and beta-carotene , respectively , but only by 14 % ( 95 % CI : -33 to 93 % ) among those receiving vitamin A. Thus , 6-mo mortality was higher among infants of women who had night blindness during pregnancy . Maternal receipt of vitamin A reduced this risk Objectives : The promotion of exclusive 
    Output:
    
Authors ' conclusions Antepartum or postpartum vitamin A supplementation , or both , probably has little or no effect on mother‐to‐child transmission of HIV in women living with HIV infection and not on antiretroviral drugs .