Cigarette smoking and maternal-child HIV transmission

We investigated the association of cigarette smoking with maternal-child HIV transmission, adjusting for illicit drug use, maternal clinical status, and delivery factors. Vital statistics birth data were linked to the New York State Medicaid HIV/AIDS Research Database for HIV-infected women delivering a liveborn singleton from 1988 through 1990. Follow-up of these children was accomplished by Medicaid data ≥2 years after birth, and their HIV status was ascertained by a clinically based classification. The adjusted relative risk or hazard (RH) of transmission for maternal factors was determined from Cox models. The overall transmission was 24.5% for the 901 maternal-child pairs. Smokers comprised 40% of women with data on smoking (n = 768); their transmission rate was 31% versus 22% for nonsmokers (p = 0.02). In the entire cohort, the adjusted RH of transmission for smokers was 1.45 (95% confidence interval [CI] 1.07-1.96); among women with advanced HIV, the adjusted RH was even higher (RH = 1.71; 95% CI 1.14-2.58). Users of cocaine (15% of the cohort) or of mixed or unspecified illicit drugs (28%) had higher transmission rates in unadjusted analysis (33%, p = 0.06 and 31%, p = 0.06 respectively); after adjustment for smoking and other maternal factors, neither cocaine (RH = 1.04 (95% CI 0.66-1.63)) nor mixed nor unspecified drug use (RH = 1.13 (95% CI = 0.75-1.70)) was significantly associated with transmission. Our data document an association of cigarette smoking during pregnancy with an increased risk of maternal-child HIV transmission that can be added to the growing list of complications caused by cigarette smoking.