A Cohort Study On The Effects Of Obstetric Factors On Mother - To - Child Transmission Of HIV / AIDS

BackgroundElective cesarean section is preferred as a regular PMTCT (prevention of mother-to-child transmission of HIV) intervention in United States and most European countries, but it is not recommended for developing countries. In China there is no national guideline of clinical services for HIV-infected pregnant women when they are in labor and delivery till now. The role of elective cesarean section in PMTCT in our country is not confirmed. This study aims to explore the impact of obstetric factors especially the mode of delivery on MTCT (mother-to-child transmission) risk of HIV, and to develop the guideline of clinical services for HIV-infected pregnant women in labor and delivery.Objective1. To explore the impact of the mode of delivery on MTCT risk of HIV;2. To explore the impact of other obstetric factors on MTCT risk of HIV, including the duration of labor, invasive operations and so on.MethodsA retrospective&prospective cohort study, in which HIV-infected pregnant women and their babies were recruited and followed up to18months after the delivery, was carried out in11districts with high HIV prevalence in Henan, Guangxi, Yunnan, and Xinjiang provinces. The series of structured questionnaires and laboratory testing were used to get the demographic characteristics, behavioral characteristics, pregnancy complications, CD4+T lymphocyte count, HIV viral load, antiviral medication and other baseline characteristics of HIV-infected pregnant women. Obstetric information such as the mode of delivery, the duration of labor and invasive operations was collected by reviewing medical records. Based on their modes of delivery, the eligible pregnant women were recruited to cesarean section group (CS) and vaginal delivery group (VD). The babies were followed-up until18months old to get their HIV status by early infant diagnosis (EID) or HIV antibody testing. Univariate and multivariate statistical analyses, including chi-square test, Mantel-Haenszel(MH) test and multivariate logistic regression, were applied to compare the MTCT risk between different groups.Main results1042pairs of HIV-infected pregnant women and their non-breastfeeding live birth babies with clear HIV status were recruited in the study.426pairs were in CS and616pairs were in VD. Most of the baseline characteristics were comparable between groups.1. MTCT rates in CS and VD were7.0%and6.3%respectively. The relative risk (RR) of CS to VD was1.008(95%CI0.975～1.042), adjusted RR ranged from0.902to1.678after MH analysis, adjusted Odds Ratio(OR) was1.114(95%CI0.631～1.966) and1.753(95%CI0.783～3.928)(viral load into the regression model) after logistic regression analysis. No statistically significant difference was found in comparison of CS with VD.2. MTCT rates in elective cesarean section group (elective CS) and emergency cesarean section group (emergency CS) were6.3%and7.9%respectively. The RR of elective CS to emergency CS was0.982(95%CI0.932～1.035), adjusted RR ranged from0.692to1.267after MH analysis, adjusted OR was0.960(95%CI0.421～2.188) after logistic regression analysis. No statistically significant difference was found in comparison of elective CS with emergency CS.3. The RR of elective CS to VD was0.999(95%CI0.960～1.039), adjusted RR ranged from0.765to1.656after MH analysis, adjusted OR was1.179(95%CI0.577～2.408) and1.946(95%CI0.766～4.949)(viral load into the regression model) after logistic regression analysis. No statistically significant difference was found in comparison of elective CS with VD.4. MTCT rates in duration labor>8h&2nd stage>15min group (LD) and duration labour≤8h or2nd stage≤15min group (SD) were7.9%and5.1%respectively. The RR of LD to SD was1.030(95%CI0.982～1.081), adjusted RR ranged from1.223to2.894after MH analysis, adjusted OR was1.883(95%CI0.854～4.150) and2.784(95%CI0.720～10.770)(viral load into the regression model) after logistic regression analysis. No statistically significant difference was found in comparison of LD with SD.5. MTCT rates in invasive operation group (IO) and non-invasive operation group (NIO) were7.3%and6.1%respectively. The RR of IO to NIO was1.013(95%CI0.957～1.073), adjusted RR ranged from0.689to1.869after MH analysis, adjusted OR was1.196(95%CI0.500～2.860)and1.920(95%CI0.533～6.921)(viral load into the regression model) after logistic regression analysis. No statistically significant difference was found in comparison of IO with NIO.Conclusion1In the condition of using antiretroviral drugs, cesarean section may not reduce MTCT risk of HIV in areas with high HIV prevalence in China;2In China, elective cesarean section may not reduce MTCT risk of HIV, but there is declining trend in the condition of using combined antiretroviral drugs early and on standard;3Duration of labor>8h&2nd stage>15min, and invasive operations in vaginal delivery may not increase MTCT risk of HIV, but further study with more samples is needed.