BACKGROUND A single recent study has suggested a decrease in HIV risk for women attending antenatal clinics (ANCs) in southern India. Yet, some have questioned the validity of the Indian national surveillance data and analyses. Previous studies suggest that the only major HIV risk factor for married Indian women is the risk behavior of their husbands. Therefore, to address concerns about potential selection bias in the analysis of sentinel surveillance data from multiple sites, we estimated the trajectory of HIV transmission rates among recently married, monogamous, primigravid women attending a single large ANC in Pune, India. METHODS Participants were self-referred, young, primigravid women from 18 to 27 years of age consenting to HIV screening. Time trends in HIV prevalence over 3.5 years were evaluated by logistic regression adjusted for age. HIV incidence was estimated by dividing the number of HIV-infected mothers by an estimate of exposure person-time, which was an estimate of the average age-specific duration of marriage. RESULTS Between August 16, 2002 and February 28, 2006, 30,085 (79.5%) of 37,858 pregnant women consented to HIV screening; 10,982 (36.5%) were primigravid and their age range was from 18 to 27 years. HIV infection risk declined over 3.5 years among primigravid women. An estimated 19,739 person-years (PYs) of exposure yielded an overall HIV incidence rate 1.25/100 PYs (95% confidence interval [CI]: 1.10 to 1.42). Estimated HIV incidence decreased from 2.2/100 PYs (95% CI: 1.6 to 3.0) in 2002 to 2003 to 0.73/100 PYs (95% CI: 0.5 to 1.0) in 2006. CONCLUSIONS HIV infection risk among young primigravid women in Pune seems to have decreased over the past 3.5 years. A decreasing HIV risk among pregnant women in Pune would also decrease the number of HIV-exposed infants. We hypothesize that decreased high-risk sexual behavior among young recently married men is most likely contributing to a decreasing risk to their wives and children in Pune.