HIV11: UK Study Finds HIV+ Women on Antiretroviral Therapy Have Higher Premature Birth Rate


A review of clinical records from Central Manchester University Hospitals has found more evidence of an increased rate of preterm delivery of babies born to HIV positive women who are taking antiretroviral therapy (ART), according to a study presented at the 11th International Congress on Drug Therapy in HIV Infection in Glasgow this month.

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The study found a higher rate of preterm delivery for mothers who started ART during pregnancy. However, it also found that the preterm delivery rate was somewhat lower in women who had large CD4 T-cell count rises. The researchers therefore recommend that it may be better for women to start ART well in advance of any planned pregnancy rather than start during pregnancy.

The reason for the higher rate of preterm delivery remains unknown. It does not seem to be due to immune restoration in the mother; other theories, such as changes in liver enzyme activity in women on boosted protease inhibitors (PIs) or increased gastrointestinal side effects, do not seem to be borne out by the fact that preterm birth was no more likely for women taking protease inhibitors than any other drug class.

The study found that the prevalence of any early birth (defined as delivery before 37 weeks’ pregnancy) was 10.7% for women on ART (10.6% for women on PI-containing regimens; 10.8% for women on non-PI-based regimens). This compared with 7.5% for the general U.K. population.

Babies delivered between 34 and 37 weeks generally do not have a higher rate of health problems than babies born on term at 39 weeks, though they may suffer from low birth weight. The rate of delivery of babies born before 34 weeks, who have a higher risk of health problems due to prematurity, was 5.8% (6.5% for women on PIs), compared with 3.6% for the general population.

This study was a retrospective case note review of all HIV positive pregnant women treated at North Manchester University Hospital between 2003 and 2012 who took ART at some point during pregnancy.

Altogether there were 208 pregnancies in 157 women; 91% of them were of black African ethnicity, with ages ranging from 16 to 43. Most women (84%) had an undetectable HIV viral load at delivery (under 40 copies/mL) and the range of viral loads in the detectable minority was 47 to 9120 copies/mL. Just over one-quarter (28%) of women were diagnosed with HIV during pregnancy, the others beforehand; two-thirds of women who started ART during pregnancy continued on it after having their baby.

Most women (82%) were on PIs, primarily ritonavir-boosted lopinavir (Kaletra), and the most common non-PI third agent used was nevirapine (Viramune). No woman took efavirenz (Sustiva or Stocrin). The most common NRTIs were zidovudine (AZT; Retrovir) and lamivudine (3TC; Epivir).

Women starting ART during pregnancy were 62% more likely to have preterm delivery than women who had started ART earlier, although this was not statistically significant. There was a trend for preterm delivery to increase with age (6.7% more relative risk per year of age).

A U.K. study cannot tell whether this increased preterm delivery rate is associated with ART use or with having HIV regardless of ART, as few HIV positive women go untreated. A recent study from Botswana found a higher rate of preterm delivery among women taking combination ART compared with zidovudine monotherapy, but also found raised rates in all women with HIV compared to the general population.

It is also worth pointing out that 40% of preterm delivery in the general population cannot be traced to any cause. Until risk factors are teased out further, the best advice for women with HIV seems to be to start ART in advance of pregnancy and to ensure intensive monitoring of maternal and baby health during pregnancy.



M Cheshire, M Kingston, O McQuillan, and M Gittins. Are HIV-related factors associated with pre-term delivery in a UK inner city setting? 11th International Congress on Drug Therapy in HIV Infection (HIV11). Glasgow, November 11-15, 2012. Abstract P190.