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  ID Week
Oct 8-12 2014
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Preterm Delivery Rate Doubled With HIV in Canada--Boosted PIs Key Factor
  IDWeek 2014, October 8-12, 2014, Philadelphia
Mark Mascolini
Preterm delivery incidence among HIV-positive women across Canada doubled the general-population average, according to results of a 1987-2013 study [1]. Preterm delivery risk was more than 50% higher among women taking a ritonavir-boosted protease inhibitor (PI) than among those taking an unboosted PI.
Canadian researchers who conducted this study noted that research differs on whether antiretroviral therapy (ART) inflates chances of preterm delivery. European studies determined that combination ART raises the risk of preterm delivery 1.5- to 3-fold [2], while North American studies found no such association [3]. To learn more about the impact of HIV infection and ART on preterm delivery and small for gestational age (SGA) status, these investigators analyzed findings from the Canadian Perinatal HIV Surveillance Program, which collects data on perinatal HIV exposure from 22 sites across the country.
The investigators defined preterm delivery as less than 37 weeks gestational age and SGA as weight less than the 10th percentile for age. They used multivariable logistic regression to identify preterm delivery risk factors after adjusting for known risk variables and accounting for dependence between multiple pregnancies in the same woman.
The database yielded 3236 live births from singleton pregnancies without vertical HIV transmission. Gestational age at birth was available for 2626 of those deliveries (in 2175 women), and 427 of those 2626 deliveries (16.26%) were preterm. That compares with an 8% preterm delivery rate across Canada. Among deliveries in HIV-positive women, 13% were at gestational age 32 to 36 weeks, 2% at 28 to 31 weeks, and 1% at fewer than 28 weeks. From 1987 through 2013, preterm delivery rates dropped from 18.7% in the early years to 13.5% in the middle years then rebounded to 18.0% in the most recent years. Overall SGA incidence was 20.48%.
Logistic regression analysis identified five independent predictors of preterm delivery at the following adjusted odds ratios (aOR):
-- Aboriginal race vs white: aOR 1.49, P = 0.029
-- Maternal injection drug use vs sexual HIV transmission: aOR 1.99, P < 0.001
-- No ART during pregnancy vs unboosted PI: aOR 1.61, P = 0.041
-- Boosted PI during pregnancy vs unboosted PI: aOR 1.54, P = 0.014
-- ART start at gestation weeks 21-27 vs weeks 13-20: aOR 3.17, P = 0.011
The researchers concluded that HIV-positive pregnant women in Canada have higher rates of preterm delivery and SGA neonates than women in the general population. They suggested that "a modifiable risk factor [for preterm delivery] may be the type of ART regimen used," since ritonavir-boosted PI regimens were associated with preterm delivery.
1. Kakkar F, Boucoiran I, Lee T, et al. High rates of preterm birth and small for gestational age in a cohort of HIV infected women in Canada: role of ritonavir boosted regimens? IDWeek 2014. October 8-12, 2014, Philadelphia. Abstract 1614.
2. Thorne C, Townsend CL. A new piece in the puzzle of antiretroviral therapy in pregnancy and preterm delivery risk. Clin Infect Dis. 2012;54:1361-1363.
3. Kourtis AP, Schmid CH, Jamieson DJ, Lau J. Use of antiretroviral therapy in pregnant HIV-infected women and the risk of premature delivery: a meta-analysis. AIDS. 2007;21:607-615.