***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 
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    Input: BACKGROUND The AIDS Clinical Trials Group protocol 076 zidovudine prophylaxis regimen for HIV-1-infected pregnant women and their babies has been associated with a significant decrease in vertical HIV-1 transmission in non-breastfeeding women in developed countries . We compared the safety and efficacy of short-course nevirapine or zidovudine during labour and the first week of life . METHODS From November , 1997 , to April , 1999 , we enrolled 626 HIV-1-infected pregnant women at Mulago Hospital in Kampala , Ug and a. We r and omly assigned mothers nevirapine 200 mg orally at onset of labour and 2 mg/kg to babies within 72 h of birth , or zidovudine 600 mg orally to the mother at onset of labour and 300 mg every 3 h until delivery , and 4 mg/kg orally twice daily to babies for 7 days after birth . We tested babies for HIV-1 infection at birth , 6 - 8 weeks , and 14 - 16 weeks by HIV-1 RNA PCR . We assessed HIV-1 transmission and HIV-1-free survival with Kaplan-Meier analysis . FINDINGS Nearly all babies ( 98.8 % ) were breastfed , and 95.6 % were still breastfeeding at age 14 - 16 weeks . The estimated risks of HIV-1 transmission in the zidovudine and nevirapine groups were : 10.4 % and 8.2 % at birth ( p=0.354 ) ; 21.3 % and 11.9 % by age 6 - 8 weeks ( p=0.0027 ) ; and 25.1 % and 13.1 % by age 14 - 16 weeks ( p=0.0006 ) . The efficacy of nevirapine compared with zidovudine was 47 % ( 95 % CI 20 - 64 ) up to age 14 - 16 weeks . The two regimens were well tolerated and adverse events were similar in the two groups . INTERPRETATION Nevirapine lowered the risk of HIV-1 transmission during the first 14 - 16 weeks of life by nearly 50 % in a breastfeeding population . This simple and inexpensive regimen could decrease mother-to-child HIV-1 transmission in less-developed countries The safety , toxicity , and pharmacokinetics of intrapartum and early newborn nevirapine were evaluated in 17 human immunodeficiency virus type 1-infected women in labor and their newborns . No adverse effects of nevirapine were noted in any study mothers or infants . Following maternal dosing with 200 mg during labor , concentrations exceeding 100 ng/mL ( 10 times the in vitro IC50 ) were achieved in the newborns .  Nevirapine elimination was prolonged in both mothers and infants , with median half-lives ranging from 36.8 to 65.7 h. Administration of 200 mg orally to the mothers in labor and of a single 2-mg/kg oral dose to the infants at 48 - 72 h after birth maintained serum concentrations in the infants > 100 ng/mL through 7 days of life BACKGROUND Perinatal transmission of human immunodeficiency virus ( HIV ) type 1 contributes significantly to infant mortality . Exposure in the birth canal may account for some transmission . We examined the efficacy of a birth canal washing procedure in reducing perinatal transmission in Malawi . METHODS The infection status of infants of 3327 control women ( conventional delivery procedures ) was compared with that of 3637 infants of intervention-delivered women . The infants ' HIV status was determined by polymerase chain reaction on dried blood spots collected at 6 and 12 weeks of age . The intervention consisted of manual cleansing of the birth canal with a cotton pad soaked in 0.25 % chlorhexidine , which was done on admission in labour and every 4 h until delivery . FINDINGS No adverse reactions to the intervention procedure were seen . 2094 ( 30 % ) of the enrolled women were HIV-infected , and 59 % of their infants were seen in follow-up . Among 982 vaginal vertex singleton deliveries to HIV-infected women , 269 ( 27 % ) infants were infected . The intervention had no significant impact on HIV transmission rates ( 27 % in 505 intervention women compared with 28 % in 477 control women ) , except when membranes were ruptured more than 4 h before delivery ( transmission 25 % in the intervention group vs 39 % in the control group ) . INTERPRETATION If birth canal exposure is an important risk factor , different or additional methods to reduce the risk of perinatal HIV transmission should be tested . Alternatively , perhaps birth canal exposure is not a major contributor to perinatal infection risk BACKGROUND In HIV-1-infected women , poor micronutrient status has been associated with faster progression of HIV-1 disease and adverse birth outcomes . We assessed the effects of vitamin A and multivitamins on birth outcomes in such women . METHODS In Tanzania , 1075 HIV-1-infected pregnant women at between 12 and 27 weeks ' gestation received placebo ( n=267 ) , vitamin A ( n=269 ) , multivitamins excluding vitamin A ( n=269 ) , or multivitamins including vitamin A ( n=270 ) in a r and omised , double-blind , placebo-controlled trial with a 2x2 factorial design . We measured the effects of multivitamins and vitamin A on birth outcomes and counts of T lymphocyte subsets . We did analyses by intention to treat . RESULTS 30 fetal deaths occurred among women assigned multivitamins compared with 49 among those not on multivitamins ( relative risk 0.61 [ 95 % CI 0.39 - 0.94 ] p=0.02 ) . Multivitamin supplementation decreased the risk of low birthweight ( < 2500 g ) by 44 % ( 0.56 [ 0.38 - 0.82 ] p=0.003 ) , severe preterm birth ( < 34 weeks of gestation ) by 39 % ( 0.61 [ 0.38 - 0.96 ] p=0.03 ) , and small size for gestational age at birth by 43 % ( 0.57 [ 0.39 - 0.82 ] p=0.002 ) . Vitamin A supplementation had no significant effect on these variables . Multivitamins , but not vitamin A , result ed in a significant increase in CD4 , CD8 , and CD3 counts . INTERPRETATION Multivitamin supplementation is a low-cost way of substantially decreasing adverse pregnancy outcomes and increasing T-cell counts in HIV-1-infected women . The clinical relevance of our findings for vertical transmission and clinical progression of HIV-1 disease is yet to be ascertained BACKGROUND AND METHODS Maternal-infant transmission is the primary means by which young children become infected with human immunodeficiency virus type 1 ( HIV ) . We conducted a r and omized , double-blind , placebo-controlled trial of the efficacy and safety of zidovudine in reducing the risk of maternal-infant HIV transmission . HIV-infected pregnant women ( 14 to 34 weeks ' gestation ) with CD4 + T-lymphocyte counts above 200 cells per cubic millimeter who had not received antiretroviral therapy during the current pregnancy were enrolled . The zidovudine regimen included antepartum zidovudine ( 100 mg orally five times daily ) , intrapartum zidovudine ( 2 mg per kilogram of body weight given intravenously over one hour , then 1 mg per kilogram per hour until delivery ) , and zidovudine for the newborn ( 2 mg per kilogram orally every six hours for six weeks ) . Infants with at least one positive HIV culture of peripheral-blood mononuclear cells were classified as HIV-infected . RESULTS From April 1991 through December 20 , 1993 , the cutoff date for the first interim analysis of efficacy , 477 pregnant women were enrolled ; during the study period , 409 gave birth to 415 live-born infants .  HIV-infection status was known for 363 births ( 180 in the zidovudine group and 183 in the placebo group ) . Thirteen infants in the zidovudine group and 40 in the placebo group were HIV-infected . The proportions infected at 18 months , as estimated by the Kaplan-Meier method , were 8.3 percent ( 95 percent confidence interval , 3.9 to 12.8 percent ) in the zidovudine group and 25.5 percent ( 95 percent confidence interval , 18.4 to 32.5 percent ) in the placebo group . This corresponds to a 67.5 percent ( 95 percent confidence interval , 40.7 to 82.1 percent ) relative reduction in the risk of HIV transmission ( Z = 4.03 , P = 0.00006 ) . Minimal short-term toxic effects were observed . The level of hemoglobin at birth in the infants in the zidovudine group was significantly lower than that in the infants in the placebo group . By 12 weeks of age , hemoglobin values in the two groups were similar . CONCLUSIONS In pregnant women with mildly symptomatic HIV disease and no prior treatment with antiretroviral drugs during the pregnancy , a regimen consisting of zidovudine given ante partum and intra partum to the mother and to the newborn for six weeks reduced the risk of maternal-infant HIV transmission by approximately two thirds We conducted a double-blind , placebo-controlled trial of the efficacy of oral azidothymidine ( AZT ) in 282 patients with the acquired immunodeficiency syndrome ( AIDS ) manifested by Pneumocystis carinii pneumonia alone , or with advanced AIDS-related complex . The subjects were stratified according to numbers of T cells with CD4 surface markers and were r and omly assigned to receive either 250 mg of AZT or placebo by mouth every four hours for a total of 24 weeks . One hundred forty-five subjects received AZT , and 137 received placebo .  When the study was terminated , 27 subjects had completed 24 weeks of the study , 152 had completed 16 weeks , and the remainder had completed at least 8 weeks . Nineteen placebo recipients and 1 AZT recipient died during the study ( P less than 0.001 ) . Opportunistic infections developed in 45 subjects receiving placebo , as compared with 24 receiving AZT . The base-line Karnofsky performance score and weight increased significantly among AZT recipients ( P less than 0.001 ) . A statistically significant increase in the number of CD4 cells was noted in subjects receiving AZT ( P less than 0.001 ) . After 12 weeks , the number of CD4 cells declined to pretreatment values among AZT recipients with AIDS but not amonG AZT recipients with AIDS-related complex . Skin-test anergy was partially reversed in 29 percent of subjects receiving AZT , as compared with 9 percent of those receiving placebo ( P less than 0.001 ) . These data demonstrate that AZT administration can decrease mortality and the frequency of opportunistic infections in a selected group of subjects with AIDS or AIDS-related complex , at least over the 8 to 24 weeks of observation in this study The goal of this exercise was to provide estimates of the mother-to-child transmission rate ( TR ) of human immunodeficiency virus type 1 ( HIV-1 )  , calculated according to st and ardized methods . Prospect i ve cohort studies in Africa ( 8) , the Caribbean ( 1 ) , Europe ( 3 ) , and the U.S.A. ( 1 ) observed from birth children born to women known to be HIV infected at the time of delivery .  TRs were calculated and compared by investigators during a meeting in Ghent ( Belgium ) in September 1993 according to agreed methodology . TRs were calculated following the direct and the indirect methods developed in 1992 by the Ghent Working Group . The direct method uses a classification of children born to HIV-seropositive mothers according to their probable HIV infection status at 15 months of age or before , if they die or are lost to follow-up . Minimum , intermediate , and maximum estimates of TR are computed depending on how children classified as indeterminate are counted . The indirect method is applied for studies with a comparison cohort of children born to HIV-seronegative mothers .  TRs in developed countries ranged from 14 to 25 % with the direct method ( intermediate estimate ) . In the developing world , they ranged from 13 to 42 % with the direct method , from 21 to 43 % with the indirect method , and most of the studies reported a TR in the range of 25 to 30 % . With use of a st and ardized methodology , the overall TR of HIV-1 tends to be higher in Africa than in Europe or the U.S.A. ( ABSTRACT TRUNCATED AT 250 WORDS CONTEXT With the success of zidovudine chemoprophylaxis for prevention of perinatal transmission of the human immunodeficiency virus ( HIV ) , an increasing number of 
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There is no evidence that ' long course therapy ' is superior to ' short course therapy ' .
REVIEW ER 'S CONCLUSIONS Zidovudine , nevirapine and delivery by elective caesarean section appear to be very effective in decreasing the risk of mother-to-child transmission of HIV infection