Incidence of and socio-biologic risk factors for spontaneous preterm birth in HIV positive Nigerian women

BACKGROUND Recent studies have identified HIV as a leading contributor to preterm delivery and its associated morbidity and mortality. However little or no information exists in our sub-region on this subject. Identifying the factors associated with preterm delivery in HIV positive women in our country and sub-region will not only prevent mother to child transmission of HIV virus but will also reduce the morbidity and mortality associated with prematurity and low birth weight. This study was designed to determine the incidence and risk factors for preterm delivery in HIV positive Nigerians. METHOD The required data for this retrospective study was extracted from the data base of a cohort study of the outcome of prevention of mother to child transmission at the Nigerian Institute of Medical Research, Lagos. Only data of women that met the eligibility of spontaneous delivery after 20 weeks of gestation were included. Ethical approval was obtained from the Institution's Ethical Review Board. RESULTS 181 women out of the 1626 eligible for inclusion into the study had spontaneous preterm delivery (11.1%). The mean birth weight was 3.1 ± 0.4 kg, with 10.3% having LBW. Spontaneous preterm delivery was found to be significantly associated with unmarried status (cOR: 1.7;1.52-2.57), baseline CD4 count <200 cells/mm(3) (cOR: 1.8; 1.16-2.99), presence of opportunistic infection at delivery (cOR: 2.2;1.23-3.57), multiple pregnancy (cOR 10.4; 4.24 - 26.17), use of PI based triple ARV therapy (eOR 10.2; 5.52 - 18.8) in the first trimester (cOR 2.5; 1.77 - 3.52) on univariate analysis. However after multivariate analysis controlling for potential confounding variables including low birth weight, only multiple pregnancy (aOR: 8.6; CI: 6.73 - 12.9), presence of opportunistic infection at delivery (aOR: 1.9; CI: 1.1 - 5.7), and 1st trimester exposure to PI based triple therapy (aOR: 5.4; CI: 3.4 - 7.8) retained their significant association with preterm delivery. CONCLUSION The spontaneous preterm delivery rate among our cohort was 11.1%. HIV positive women with multiple pregnancies, symptomatic HIV infection at delivery and first trimester fetal exposure to PI based triple therapy were found to be at risk of spontaneous preterm delivery. Early booking and non-use of PI based triple therapy in the first trimester will significantly reduce the risk of preterm delivery.