Infants Likelier to Get HIV If Mother Infected Through Sex

Daniel M. Keller, PhD

October 18, 2011

October 18, 2011 (Belgrade, Serbia) — In a retrospective study of HIV-infected women giving birth in a hospital in Romania, the rate of transmission of the virus from mother to infant was "strikingly higher" if the mothers acquired the infection through sexual contact (SI) than if they were infected by the parenteral route (PI), especially if the mothers were young at the time of infection, Cristiana Oprea, MD, PhD, from the Dr. Victor Babes Clinical Hospital of Infectious and Tropical Diseases in Bucharest, reported here at the 13th European AIDS Conference of the European AIDS Clinical Society.

The AIDS epidemic in Romania is characterized in part by a homogeneous, large cohort of youth and adolescents infected with the F-1 strain of HIV by the parenteral route in the late 1980s. Several studies around the world have characterized pregnancy outcomes for mothers who were vertically infected, but few publications have reported on mothers who acquired HIV through the parenteral route.

Demographics and Treatment Characteristics

PI mothers were younger than SI mothers at the time of delivery (median, 19 vs 26 years) and were more likely to be coinfected with hepatitis B, but their rate of mother-to-child transmission (MTCT) of HIV was much lower, probably because they had been followed and were receiving treatment for an extended time.

The PI mothers were diagnosed with HIV at a median age of 9 years (range, 1 to 18 years), and 93% knew their HIV serostatus before becoming pregnant; in contrast, SI mothers were diagnosed at a median age of 25 years (range, 14 to 38 years), and only 42% were aware of their serostatus before becoming pregnant (PI vs SI mothers for age at delivery, age at diagnosis, and knowledge of serostatus, P < .001 for all).

The median maternal CD4 counts did not differ significantly at the time of delivery between the PI and SI mothers (460 vs 497 cells/mm3; P = .599). However, the SI mothers had a higher viral load than the PI mothers (4.7 vs 3.6 log10 viral copies/mL; P = .015). Viral RNA was undetectable in 81.2% of the PI group and in 40.0% of the SI group (P < .001).

Fifty-five percent of PI mothers received antiretroviral therapy (ART) before pregnancy, compared with 3% in the SI mothers (P < .001). PI mothers had a mean exposure to ART of 26.4 weeks during pregnancy, compared with 8.5 weeks for the SI mothers (P < .001).

Results Show Importance of Maternal Treatment

The investigators found no perinatal transmission of HIV, in either the SI or PI mother–child pairs, when there was complete prophylaxis. They said that the number of pregnancies of PI women has been increasing as they reach child-bearing age and start families. Most of the PI mothers were unemployed, unmarried, and part of a serodiscordant couple.

SI mothers have tended to be diagnosed and treated for HIV later than the PI mothers, especially in the first years of the study, but mandatory testing for HIV in pregnancy "dramatically reduced" late diagnoses and improved pregnancy outcomes, Dr. Oprea reported.

In this retrospective, parallel, single-center study, 108 PI and SI HIV-infected mothers gave birth to 119 infants from January 2000 to January 2011. Infants were considered HIV-negative if 3 tests for HIV viral load were negative and 1 of the tests was performed after the age of 3 months, or if an HIV antibody test was negative after 18 months.

Forty-seven PI mothers gave birth to 53 infants, only 1 of whom was infected with HIV. Sixty-one SI mothers gave birth to 66 infants, 17 of whom were infected.

"There is a statistically significant difference in the MTCT rate between these groups — 1.8% in the PI group and more than 25% in the SI group. So the overall MTCT rate was very high — 15% — due to late diagnosis in the SI group," Dr. Oprea reported (P < .001).

Treating mothers with highly active antiretroviral therapy (HAART) appears to be safe for the offspring and effective in reducing MTCT. "There were between 3 and 8 HAART regimens used before pregnancy. We have all HIV-uninfected children born to these women, and we didn't record any congenital abnormality," Dr. Oprea said. "In 68 mother–child pairs with only ART prophylaxis and no breastfeeding, the mother-to-child transmission rate was 0, [regardless of] the mode of delivery or the mode of HIV transmission in the mothers."

Over the years of the study, the number of PI mothers having babies has increased as they have reached child bearing age. The number of SI mothers has remained relatively constant. Over this same 10-year period, the number of HIV-infected newborns has decreased because HIV testing of all pregnant women has been implemented in Romania. The number of infected newborns in 2009 and 2010 was 0 in each year, but there have been 2 cases in 2011 born to SI mothers.

A limitation of the study is that it was retrospective for the first 5 years, and some data were missing, especially for SI mothers. It was also a single-center study and should be confirmed elsewhere, Dr. Oprea advised.

Session cochair Karina Butler, MB, consultant in pediatric infectious diseases and head of the multidisciplinary infectious disease/immunology service at Our Lady's Hospital for Sick Children in Dublin, Ireland, told Medscape Medical News that the study reinforces the message that young women who know their diagnosis and are receiving treatment, particularly before conception, "have a much, much lower risk of transmission." She said French cohort studies have shown the same thing.

"It highlights the problem we have of young women who are newly acquiring infection, and also those who are being newly diagnosed with infection, even in the late stages of pregnancy, and not getting on treatment in time to prevent mother-to-infant transmission," Dr. Butler noted.

She said she does not think there is a biologic difference in the infection once it has been acquired, so the differences between the findings for the PI and SI women relate more to their knowing their HIV status and receiving treatment. Since PI women are receiving ongoing care, they are more likely to be referred to antenatal care early.

"The problem with the SI women was they presented very late to treatment," Dr. Butler said.

She explained that in the absence of any treatment, there is about a 30% chance of in utero transmission of HIV. "So if you have someone presenting late, they may have already transmitted [the virus] in utero, particularly if it's a new infection. The woman who seroconverts in pregnancy or gets a new infection in pregnancy — she's the one who's at highest risk of early in utero transmission," she said. If an infant is not infected in utero, treating the mother in the peripartum period is very effective in preventing transmission during delivery. "But we want to have women on treatment and stably suppressed," Dr. Butler said. "In Romania, the overall transmission rate was 5%, so they still have a way to go."

The study did not have any commercial funding. Dr. Butler has disclosed no relevant financial relationships.

13th European AIDS Conference of the European AIDS Clinical Society (EACS): Abstract PS4/1. Presented October 13, 2011.


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