Prednisolone pharmacokinetics after oral prednisone administration in paediatric patients with kidney transplant.

AIMS: Glucocorticoids are 1 of the primary treatments in paediatric kidney transplantation. The aims of this study were: (i) to build a population pharmacokinetics (PPK) model of free prednisolone, which is the active form of prednisone, in paediatric kidney transplant recipients; (ii) to identify covariates accounting for interindividual variability (IIV) of pharmacokinetics (PK) parameters; and (iii) to investigate drug exposure-safety relationships. METHODS: Ninety-seven samples were obtained from 39 paediatric kidney transplant recipients (aged 3.4-17.2 years) in order to investigate prednisone PPK. We selected children receiving oral prednisone as part of their immunosuppressive regimen. A PPK analysis was performed using Monolix. RESULTS: A 1-compartment model best described prednisolone concentrations. Large IIV was observed as prednisolone was undetectable at H12 in some patients but could still be detected at H24 in others. Both bodyweight and ciclosporin cotreatment influenced the PK. The clearance (CLU ) and volume of distribution of free prednisolone allometrically scaled to 70 kg were 27.6 L/h and 101 L. Ciclosporin cotreatment decreased CLU by 67%. High blood pressure and new onset diabetes after transplantation were associated with daily free prednisolone exposure. CONCLUSION: This study is the first analysis of prednisolone PPK in kidney-transplanted children. Some of the IIV in the PK parameters was explained by bodyweight and ciclosporin cotreatment. These data suggest that dose adjustment is required after identifying variability factors to optimize efficacy and limit side effects. The use of therapeutic drug monitoring in kidney-transplanted children may be useful, especially with respect to safety issues.

Saliva for molecular detection of SARS-CoV-2 in pre-school and school-age children.

SARS-CoV-2 diagnosis is a cornerstone for the management of coronavirus disease 2019 (COVID-19). Numerous studies have assessed saliva performance over nasopharyngeal sampling (NPS), but data in young children are still rare. We explored saliva performance for SARS-CoV-2 detection by RT-PCR according to the time interval from initial symptoms or patient serological status. We collected 509 NPS and saliva paired samples at initial diagnosis from 166 children under 12 years of age (including 57 children under 6), 106 between 12 and 17, and 237 adults. In children under 12, overall detection rate for SARS-CoV-2 was comparable in saliva and NPS, with an overall agreement of 89.8%. Saliva sensitivity was significantly lower than that of NPS (77.1% compared to 95.8%) in pre-school and school-age children but regained 96% when considering seronegative children only. This pattern was also observed to a lesser degree in adolescents but not in adults. Sensitivity of saliva was independent of symptoms, in contrary to NPS, whose sensitivity decreased significantly in asymptomatic subjects. Performance of saliva is excellent in children under 12 at early stages of infection. This reinforces saliva as a collection method for early and unbiased SARS-CoV-2 detection and a less invasive alternative for young children.

Text message reminders for adolescents with poorly controlled type 1 diabetes: A randomized controlled trial.

BACKGROUND: Among adolescents with type 1 diabetes, some experience great difficulties with treatment adherence, putting them at high risk of complications. We assessed the effect of text messaging (Short Messaging Service [SMS]) on glycemic control. METHODS: A two-arm open label randomized controlled trial enrolled adolescents with type 1 diabetes aged 12-21 years with baseline HbA1c ≥ 69 mmol/mol (8.5%). The intervention group received daily SMS reminders at self-selected times about insulin injections while the control group received standard of care. The patients allocated to the control group were not aware of the intervention. RESULTS: 92 patients were randomized, 45 in the SMS arm and 47 in the control arm. After 6 months, median HbA1c level was significantly lower in the intervention arm: 73 mmol/mol (8.8%) in the SMS arm and 83 mmol/mol (9.7%) in the control arm in the intent-to-treat analysis (P = 0.03) but no longer in the per protocol analysis (P = 0.65). When we consider the proportions of patients whose HbA1c level decreased by at least 1% between baseline and 6 months, we find a significant difference among patients whose baseline HbA1c was ≥ 80 mmol/mol (9.5%) (n = 56): 60% in the SMS arm and 30.6% in the control arm had lowered their HbA1c level (P = 0.03) in the intent-to-treat analysis but not in the per-protocol analysis (P = 0.50). Patients in the SMS arm reported high satisfaction with the intervention. CONCLUSIONS: While there is a trend to lower HbA1c in the intervention group, no firm conclusions can yet be drawn. Further studies are needed to address methodological issues as we believe these interventions can support behavior change among adolescents with poorly controlled type 1 diabetes. ClinicalTrials.gov identifier: NCT02230137.

Is intrapartum intravenous zidovudine for prevention of mother-to-child HIV-1 transmission still useful in the combination antiretroviral therapy era?

BACKGROUND: Intrapartum intravenous zidovudine (ZDV) prophylaxis is a long-standing component of prevention of mother-to-child transmission (MTCT) of human immunodeficiency virus (HIV) in high-resource countries. In some recent guidelines, intravenous ZDV is no longer systematically recommended for mothers receiving combination antiretroviral therapy (cART) with low viral load. We evaluated the impact of intravenous ZDV according to viral load and obstetrical conditions. METHODS: All HIV-1-infected women delivering between 1 January 1997 and 31 December 2010 in the French Perinatal Cohort (ANRS-EPF) were analyzed if they received ART during pregnancy and did not breastfeed. We identified maternal and obstetrical characteristics related to lack of intravenous ZDV and compared its association with MTCT rate and other infant parameters, according to various risk factors. RESULTS: Intravenous ZDV was used in 95.2% of the 11 538 deliveries. Older age, multiparity, and preterm and vaginal delivery were associated with lack of intravenous ZDV (n = 554). In women who delivered with viral load ≥1000 copies/mL, the overall MTCT rate was higher without than with intravenous ZDV (7.5% vs 2.9%; P = .01); however, there was no such difference when the neonate received postnatal intensification therapy. Among them, 77% of women who had viral load <400 copies/mL, there was no difference in MTCT rate (0% without intravenous ZDV vs 0.6% with intravenous ZDV; P = .17). Intravenous ZDV was not associated with increased short-term hematological toxicity or lactate level. CONCLUSIONS: Intravenous ZDV remains an effective tool to reduce transmission in cases of virological failure, even in cART-treated women. However, for the vast majority of women with low viral loads at delivery, in the absence of obstetrical risk factors, systematic intravenous ZDV appears to be unnecessary.

Cesarean section for HIV-infected women in the combination antiretroviral therapies era, 2000-2010.

OBJECTIVE: Elective cesarean section (CS) is a proven method to prevent mother-to-child transmission (MTCT), but is no longer recommended for women with antiretroviral therapy resulting in a low viral load (VL): <400 copies/mL in French and <1000 copies/mL in US guidelines. We sought to describe mode of delivery practices in human immunodeficiency virus (HIV)-infected women and their association with MTCT and postpartum complications. STUDY DESIGN: All deliveries from HIV-1-infected women in the French Perinatal Cohort (Agence Nationale de Recherches sur le Sida/Enquête Périnatale Française) 2000 through 2010 (N = 8977) were analyzed, with additional details for 2005 through 2010 (n = 4717). RESULTS: Vaginal deliveries increased from 25% in 2000 to 53% in 2010. Over 2005 through 2010, 4300 women had VL before delivery <400 copies/mL; among them only 49.3% delivered vaginally, 22.0% had nonelective CS, and 28.7% had elective CS. Elective CS were performed for scarred uterus in 45.4%, other obstetrical indications in 37.1%, and solely because of HIV in 15.7%. Of the 417 women with VL ≥400 copies/mL, 48.9% had elective CS as recommended, 25.9% had nonelective CS, and 25.2% had vaginal delivery. The MTCT rate did not differ according to the mode of delivery in term deliveries (≥37 gestational weeks) in 2000 through 2010: 0.3% after both vaginal delivery and elective CS with VL <50 copies/mL, 4.0% vs 5.3%, respectively, with VL ≥10,000 copies/mL. In case of preterm delivery, MTCT rates tended to be higher with vaginal delivery. Postpartum complications were more frequent following CS than vaginal deliveries (6.5% vs 2.9, P < .01). CONCLUSION: Our findings suggest that HIV-infected women on antiretroviral therapy with low VL can safely opt for vaginal delivery in the absence of obstetrical risk factors.

CCR5 antagonists: a therapeutic option in HIV-1 perinatally infected children experiencing virologic failure?

OBJECTIVE: The risk of virologic failure and selection of resistant strains remains a challenge in HIV-1 perinatally infected children. HIV-1 coreceptor usage was determined in HAART-failing children followed in Necker Hospital (Paris, France) in order to estimate the proportion of these patients who may benefit from CCR5-antagonists therapy. METHODS: HIV-1 coreceptor usage was determined with the SVM(Geno2pheno10%) algorithm in 51 children with virologic failure after a median treatment exposure of 7.8 years. RESULTS: CXCR4-tropic strains were found in 31.4% of the patients. CXCR4 usage was associated with high HIV-1 DNA (P=0.01), old age (P=0.02), long ART cumulative exposure (P=0.006), and previous exposure to high number of different drugs (P=0.03) and ART combinations (P=0.03) in univariate analysis. Selection of resistant viruses and current exposure to a darunavir-based HAART tended to be more frequent in the CXCR4 group compared with the children infected with CCR5-tropic strains (P=0.06). In multivariate analysis, CXCR4 usage was exclusively correlated with HIV-1 DNA (P=0.03), which accurately reflects the cumulative exposure to viral replication over the whole duration of HIV infection. CONCLUSION: Two-thirds of HAART-failing children could benefit from CCR5 antagonists-based strategies, even in case of triple-class virologic failure. Such therapy should be discussed more appropriately at early stages of infection, when CCR5-tropic strains are most frequently isolated. However, before considering such strategies, further studies are needed to evaluate the efficacy and the tolerability of CCR5 antagonists in this pediatric population.

Previous antiretroviral therapy for prevention of mother-to-child transmission of HIV does not hamper the initial response to PI-based multitherapy during subsequent pregnancy.

BACKGROUND: Few data are available on the possible long-term negative effects of a short exposure to antiretroviral therapy (ART) for prevention of mother-to-child transmission (PMTCT). OBJECTIVE: To determine whether ART for PMTCT, discontinued after delivery, affects the virological response to highly active antiretroviral therapy (HAART) administered during subsequent pregnancies. METHODS: All current pregnancies of HIV-1-infected women enrolled in the French Perinatal Cohort (ANRS CO-01 EPF) between 2005 and 2009 and not receiving ART at the time of conception were eligible. We studied the association between history of exposure to ART during a previous pregnancy and detectable viral load (VL) under multitherapy at current delivery (VL ≥ 50 copies/mL). RESULTS: Among 1116 eligible women, 869 were ART naive and 247 had received PMTCT during a previous pregnancy. Previous ART was protease inhibitor (PI)-based HAART in 48%, non-PI-based HAART in 4%, nucleoside reverse transcriptase inhibitor bitherapy in 19% and zidovudine monotherapy in 29% of the women. At current pregnancy, women with or without prior exposure to ART had similar CD4 cell counts and VL before ART initiation. PI-based HAART was initiated in 90% of the women. VL was undetectable (<50 copies/mL) at delivery in 65% of previously ART-naive women, 72% of women previously exposed to HAART, 62% previously exposed to bitherapy, and 67% previously exposed to monotherapy for prophylaxis (P = 0.42). Detectable VL was not associated with previous exposure in multivariate analysis (adjusted OR for previous versus no previous exposure to ART: 0.92; 0.95% confidence interval: 0.59 to 1.44). CONCLUSIONS: Efficacy of PI-based combinations is not decreased in women previously exposed to various regimens of antiretroviral PMTCT.

Lopinavir/ritonavir-based antiretroviral therapy in human immunodeficiency virus type 1-infected naive children: rare protease inhibitor resistance mutations but high lamivudine/emtricitabine resistance at the time of virologic failure.

BACKGROUND: Lopinavir/ritonavir (LPV/r) is now the protease inhibitor regimen of choice in the first-line antiretroviral therapy for children <6 years of age. METHODS: We included all the human immunodeficiency virus (HIV) type 1-infected highly active antiretroviral therapy (HAART)-naive children who started an LPV/r-based regimen between 2000 and 2009 at the Necker Hospital (Paris, France). Virologic failure (VF) was defined as an HIV-RNA ≥50 copies/mL. Resistance genotypic test was performed in case of VF. RESULTS: A total of 43 children were included at a median age of 4.8 years (1.8-8.0). Median level of HIV RNA and percentage of CD4 cell count was 5.5 log10 copies/mL (4.6-6) and 15% (8-27.5), respectively. HAART included LPV/r and 2 nucleoside reverse-transcriptase inhibitors, mainly lamivudine (3TC), zidovudine, and/or abacavir. The median follow-up period was 36 months (18-72). Less than 50 copies/mL of HIV RNA was observed in 46%, 67%, and 70% of the children at months 6, 9, and 12, respectively. In all, 20 children (46.5%) experienced a VF. The risk factors of primary VF were a young age and a low socioeconomic status. The genotypic resistance test, performed for 18 of 20 children with VF, revealed 1 LPV/r-resistant virus and protease inhibitor-related major mutations without LPV/r resistance in 2 other children. Of the 18 children with VF, 15 received a 3TC-based HAART: 12 of 15 (80%) harbored a 3TC-resistant virus. No virus resistant to zidovudine or abacavir was found. CONCLUSION: In all, 70% of HAART-naive children had virologic success at month 12. The selection of LPV-resistant strains was a rare event. A high rate of selection of 3TC-mutations strengthens the recommendation to prefer a first-line 3TC-sparing regimen, particularly for children with risk factors of poor adherence.

Hematological safety of perinatal exposure to zidovudine in uninfected infants born to HIV type 1-infected women in Thailand.

The evolution of hematological parameters in HIV-1-exposed uninfected infants according to various durations of perinatal zidovudine exposure was studied. We used data prospectively collected among 1122 HIV-uninfected formula-fed infants born to HIV-infected mothers who participated in a clinical trial to prevent perinatal transmission in Thailand (PHPT-1). Infants were exposed to different durations of zidovudine both in utero and after birth. Hemoglobin level and leukocyte, absolute neutrophil, and lymphocyte counts were measured at birth and at 6 weeks of age. The association between hematological parameters at birth and the duration of zidovudine exposure in utero was studied using a linear regression model, and changes between birth and 6 weeks of age and the duration of postnatal zidovudine exposure using mixed effects models. At birth, the hemoglobin level was lower in newborns exposed to zidovudine for more than 7.5 weeks in utero (adjusted regression coefficient: -0.6 g/dl; 95% confidence interval: -1.1 to -0.1). Six weeks after birth, the hemoglobin level had decreased faster in infants administered zidovudine for more than 4 weeks (adjusted regression coefficient: -0.1 g/dl; 95% confidence interval: -0.2 to -0.1). The duration of perinatal zidovudine exposure was not associated with the evolution of leukocyte, neutrophil, and lymphocyte counts. Despite the differences in hemoglobin levels, grade 3 or 4 anemia did not significantly differ by maternal or infant zidovudine duration. The clinical impact appeared modest, but longer exposure may warrant close monitoring.

Risk of extended viral resistance in human immunodeficiency virus-1-infected Mozambican children after first-line treatment failure

Background: Resistant virus may be selected by sub-optimal control of HIV-1 replication during antiretroviral treatment. The incidence and profile of resistance in children receiving World Health Organization-recommended treatment remains to be evaluated on a large scale. Goals: Assessment of the frequency and profile of resistant virus in HIV-1-infected children, treated for at least 6 months with stavudine/zidovudine + lamivudine + nevirapine and presenting virological failure in a large access program in Maputo, Mozambique. Results: Cross-sectional evaluation of plasma HIV-1 viral load (VL) in 495 evaluable children among 512 treated for at least 6 months showed that 360 (72.7%) had a VL of <50 copies/mL of HIV-1 RNA. Genotypic resistance tests were performed in the 84 available samples from the 135 treated children with VL > or = 50 copies/mL: 92% of the viruses were resistant to lamivudine and/or nevirapine, and 15% were resistant to stavudine. Twenty children (24%) harbored virus with a extended spectrum of cross-resistance defined as resistance to the 3 drugs of the combination received by the child and/or at least 1 resistance to a drug to which the child had never been exposed (abacavir: 5%, tenofovir: 6%, didanosine: 3.5% and the new generation non nucleoside inhibitor, etravirine: 6%). The only factor identified by multivariate analysis as being associated with this extended resistance profile was the duration of treatment (aOR: 6.67 [95% CI: 1.24-35.93], P = 0.015 for treatment >24 months) with a per month increase of 1.09 (1.02-1.16) P = 0.007.

Risk of extended viral resistance in human immunodeficiency virus-1-infected Mozambican children after first-line treatment failure.

BACKGROUND: Resistant virus may be selected by sub-optimal control of HIV-1 replication during antiretroviral treatment. The incidence and profile of resistance in children receiving World Health Organization-recommended treatment remains to be evaluated on a large scale. GOALS: Assessment of the frequency and profile of resistant virus in HIV-1-infected children, treated for at least 6 months with stavudine/zidovudine + lamivudine + nevirapine and presenting virological failure in a large access program in Maputo, Mozambique. RESULTS: Cross-sectional evaluation of plasma HIV-1 viral load (VL) in 495 evaluable children among 512 treated for at least 6 months showed that 360 (72.7%) had a VL of <50 copies/mL of HIV-1 RNA. Genotypic resistance tests were performed in the 84 available samples from the 135 treated children with VL > or = 50 copies/mL: 92% of the viruses were resistant to lamivudine and/or nevirapine, and 15% were resistant to stavudine. Twenty children (24%) harbored virus with a extended spectrum of cross-resistance defined as resistance to the 3 drugs of the combination received by the child and/or at least 1 resistance to a drug to which the child had never been exposed (abacavir: 5%, tenofovir: 6%, didanosine: 3.5% and the new generation non nucleoside inhibitor, etravirine: 6%). The only factor identified by multivariate analysis as being associated with this extended resistance profile was the duration of treatment (aOR: 6.67 [95% CI: 1.24-35.93], P = 0.015 for treatment >24 months) with a per month increase of 1.09 (1.02-1.16) P = 0.007. CONCLUSIONS: Residual viral replication in children receiving stavudine/zidovudine + lamivudine + nevirapine treatment is associated with a time-dependent risk of acquiring cross-resistance, including resistance to drugs currently used for second-line treatment and also to the new generation of non nucleoside reverse transcriptase inhibitors.

No relation between in-utero exposure to HAART and intrauterine growth retardation.

BACKGROUND: The use of HAART during pregnancy is now standard care to prevent mother-to-child HIV transmission in developed countries. There is controversy about its impact on low birth weight. OBJECTIVE: To evaluate the impact of antiretroviral therapy during the pregnancy on birth weight, length and head circumference. METHODS: The study was performed in uninfected infants born to HIV-1-infected mothers, enrolled from 1990 to 2006 in the Agence Nationale de Recherche sur le SIDA French Perinatal Cohort CO1. We excluded mothers who used illicit drugs during pregnancy or had no prenatal care before the third trimester, twins and stillbirths. We used Z-scores adjusted for gestational age and sex. RESULTS: In 8192 mother-infant pairs, the mean birth weight Z-scores increased between 1990 and 1997 and then remained stable until 2006. There was no significant relation between the type of antiretroviral therapy and the proportion of small for gestational age (birth weight Z-score < or = -2SD), which was 4% overall. Infants exposed to HAART compared with monotherapy had a lower mean birth weight Z-scores (difference -0.09, 95% confidence interval -0.15 to -0.02); however, there was no difference between HAART exposure in 2005-2006 and monotherapy in 1999-2004, which corresponded to standard care during each period, respectively. Length or head circumference Z-scores were not associated with antiretroviral therapy exposure. Among pregnancies with HAART, there was no relation between the duration and type of therapy and the anthropometric parameters. CONCLUSION: Our findings in a large cohort suggest that HAART during pregnancy does not increase the incidence of infants who are small for gestational age.

Perinatal zidovudine prophylaxis in HIV type-1-infected pregnant women with thalassaemia carriage in Thailand.

BACKGROUND: To investigate a possible interaction between alpha-thalassaemia, beta-thalassaemia and haemoglobin-E trait and the haematological parameters of HIV type-1 (HIV-1)-infected pregnant women receiving zidovudine prophylaxis for the prevention of mother-to-child HIV-1 transmission in Thailand. METHODS: The study sample was composed of HIV-1-infected pregnant women receiving zidovudine (300 mg twice daily) from 28 weeks of gestational age to delivery as part of the Perinatal HIV Prevention Trial (PHPT-1), a large trial investigating zidovudine use in pregnancy. These women were randomly selected and screened for haemoglobin abnormalities. Haemoglobin levels, haematocrit and erythrocyte, leukocyte, absolute neutrophil and absolute lymphocyte counts were measured at 26, 32 and 35 weeks of gestation and at delivery. PCR genotyping techniques were used to screen for haemoglobin abnormalities, which included alpha-thalassaemia-1 Southeast Asian type deletion, beta-thalassaemia mutation (codons 41/42 [-TCTT], codon 17 [A-->T], intervening sequence-I nucleotide 1 [G-->T], codons 71/72 [+A]) and haemoglobin-E trait. The evolution of haematological parameters between 26 weeks and delivery was compared according to thalassaemia carriage using linear mixed models adjusted for baseline sociodemographic characteristics, HIV clinical stage, CD4+ T-cell count and viral load. RESULTS: At baseline, women with thalassaemia or haemoglobin-E trait had significantly lower haemoglobin level and red blood cell counts than women with no haemoglobin abnormalities, whereas absolute neutrophil and leukocyte counts were significantly higher. Exposure to zidovudine until delivery did not increase this difference. CONCLUSIONS: Zidovudine exposure did not appear to have increased haematological toxicity in HIV-1-infected pregnant women with thalassaemia.

Haematological safety of perinatal zidovudine in pregnant HIV-1-infected women in Thailand: secondary analysis of a randomized trial.

OBJECTIVES: To respond to the primary safety objective of the Perinatal HIV Prevention Trial 1 (PHPT-1) by studying the evolution of haematological parameters according to zidovudine exposure duration in HIV-1-infected pregnant women. DESIGN: Multicenter, randomized, double-blind, controlled trial of different durations of zidovudine prophylaxis. SETTING: 27 hospitals in Thailand. PARTICIPANTS: 1,436 HIV-infected pregnant women in PHPT-1. INTERVENTION: Zidovudine prophylaxis initiation at 28 or 35 wk gestation. OUTCOME MEASURES: Haemoglobin level, leucocytes, total lymphocyte counts, and absolute neutrophil counts were measured at 26, 32, and 35 wk and at delivery. The evolution of haematological parameters was estimated between 26 and 35 wk (zidovudine/placebo) and between 35 wk and delivery to compare a long versus short zidovudine exposure. For each parameter, linear mixed models were adjusted on baseline sociodemographic variables, HIV clinical stage, CD4 count, and viral load. RESULTS: Between 26 and 35 wk, haemoglobin, leucocytes, and absolute neutrophil counts decreased in zidovudine-exposed compared to unexposed women (mean difference [95% CI] -0.4 [-0.5 to -0.3], -423 [-703 to -142], -485 [-757 to -213], respectively). However, between 35 wk and delivery, the haematological parameters increased faster in women exposed to long rather than short durations of zidovudine (0.1 [0.0 to 0.1]; 105 [18 to 191]; 147 [59 to 234], respectively). At delivery, the differences were not statistically significant, except for mean haemoglobin level, which remained slightly lower in the long zidovudine treatment group (difference: 0.2 g/dl). Zidovudine had no negative impact on the absolute lymphocyte counts. CONCLUSION: Zidovudine initiated at 28 wk gestation rather than 35 wk had a transient negative impact on the evolution of haematological parameters, which was largely reversed by delivery despite continuation of zidovudine. This result provides reassurance about the safety of early initiation of zidovudine prophylaxis during pregnancy to maximize prevention of perinatal HIV.

Growth of human immunodeficiency virus-uninfected children exposed to perinatal zidovudine for the prevention of mother-to-child human immunodeficiency virus transmission.

BACKGROUND: Perinatal human immunodeficiency virus (HIV) prevention programs have been implemented in several countries, and many children have been or will be exposed to antiretrovirals in utero and during their first weeks of life. Although reducing substantially the number of infected children, the potential adverse consequences of these treatments on the health of HIV-uninfected children need to be assessed. OBJECTIVE: To investigate the impact of in utero and postnatal zidovudine exposure on the growth of HIV-uninfected children born to HIV-infected women. METHODS: We used data prospectively collected in 1408 live born children participating in a clinical trial comparing zidovudine regimens of different durations to prevent perinatal transmission in Thailand (PHPT-1). We used a linear mixed model to analyze the anthropometric measurements (weight for age, height for age and weight for height Z-scores) until 18 months of age according to zidovudine treatment duration (mothers, <7.5 weeks versus more; infants, 3 days versus >4 weeks). RESULTS: Children exposed in utero for >7.5 weeks had a slightly lower birth weight (Z-score difference, 0.08; P = 0.003). However, zidovudine exposure had no effect on the evolution of Z-scores from 6 weeks to 18 months of age. CONCLUSIONS: Although a longer in utero zidovudine exposure may have had a negative impact on birth weight, the magnitude of this effect was small and faded over time. Neither the total nor the postnatal duration of exposure was associated with changes in infant Z-scores from 6 weeks to 18 months of age.