Taking antiretroviral therapy before conception significantly reduces the risk of developing blood pressure disorders such as pre-eclampsia during pregnancy, a large review of pregnancies in South Africa’s Western Cape province has found.
The study, published in the journal AIDS, showed that women with HIV taking antiretroviral treatment (ART) had a lower risk of developing a blood pressure disorder during pregnancy than women without HIV. Taking antiretroviral treatment for at least two years before delivery slightly reduced the risk of a blood pressure disorder compared to starting treatment either just before or early in pregnancy.
Around 8%-10% of pregnancies are complicated by the development of high blood pressure. This can lead to suboptimal foetal growth, as less oxygen is transferred across the placenta. The most severe blood pressure disorder, pre-eclampsia, can lead to premature birth or stillbirth – or to eclampsia, where the mother experiences seizures, or HELLP syndrome, which may lead to kidney or liver failure.
The immune system plays a role in the development of blood pressure disorders in pregnancy and there is some evidence that by reducing immune suppression and HIV-related inflammation, antiretroviral treatment may reduce the risk of these blood pressure disorders. However, previous studies have been small and contradictory.
To clarify the risk of blood pressure disorders during pregnancy in women with HIV, researchers at universities in South Africa and the United States looked at the incidence of new blood pressure disorders during 180,533 pregnancies where delivery took place at public health facilities in South Africa’s Western Cape province in 2018 and 2019.
A new blood pressure disorder during pregnancy was defined as a disorder that occurred from week 20 of gestation onwards. The disorders included transient high blood pressure, high blood pressure through pregnancy or pre-eclampsia (including the development of pre-eclampsia in cases of pre-existing hypertension).
Routine HIV testing was offered at the first antenatal visit and uptake was high, the researchers reported. Eleven percent of pregnant women were living with HIV and on ART prior to conception, 5% began ART during pregnancy and 2% were living with HIV but had no evidence of ART during pregnancy. Eighty-one percent had no evidence of HIV.
The median duration of antiretroviral treatment was 213 weeks in those who had been taking ART before conception and 21 weeks in those who began treatment during pregnancy. The majority in both categories (79% and 91% respectively) were taking tenofovir disoproxil, emtricitabine and efavirenz as first-line treatment.
A new blood pressure disorder was diagnosed in 7.6% of pregnancies. Just under one in five (19%) had a pre-existing diagnosis of high blood pressure. The incidence of a new blood pressure disorder was highest in women with HIV not on antiretroviral treatment (9.8%), and lowest in women who started antiretroviral treatment prior to conception (6.9%). In those without HIV, the incidence was 7.7%.
The most common disorder was pre-eclampsia. This was diagnosed in almost half of all pregnancies (47%). Pre-eclampsia occurred more often in women with HIV not on antiretroviral treatment or in those who began ART during pregnancy (50% of new blood pressure disorders) and least often in women with HIV on antiretroviral treatment before conception (44% of new blood pressure disorders).
Compared to those without HIV, the prevalence of new blood pressure disorders was 10% lower in women with HIV who were on ART prior to conception and 8% lower in those who started ART during pregnancy.
After adjusting for maternal and pregnancy-related factors, the prevalence was 22% lower in those who had started ART prior to conception, 17% lower in those who started treatment during pregnancy and 17% higher in those not on antiretroviral treatment, when compared to women without HIV.
"Compared to those without HIV, the prevalence of new blood pressure disorders was 10% lower in women with HIV who were on ART prior to conception."
Older age, having twins or triplets and pre-existing high blood pressure were also associated with an increased risk of a new blood pressure disorder during pregnancy.
In women who started treatment at least 140 days (20 weeks) prior to delivery, taking a protease inhibitor-based regimen, or taking second- or third-line treatment, were each associated with a 58% higher prevalence of new blood pressure disorders when compared to non-PI-based treatment or first-line treatment.
Prevalence was 11% lower in women who had taken antiretroviral treatment for more than 100 weeks when compared to those who had taken it for more than 20 weeks during pregnancy.
Dr Amy Slogrove of Stellenbosch University and colleagues say that their study is by far the largest investigation of the relationship between antiretroviral treatment and new blood pressure disorders in pregnancy.They say that the association between longer duration of antiretroviral therapy and lower risk of a new blood pressure disorder may be explained by long-term immune stabilisation as a result of treatment. The finding should encourage further efforts to diagnose HIV in women and begin antiretroviral treatment before conception.
Slogrove AL et al. Hypertensive disorders of pregnancy and HIV: analysis of a province-wide cohort during 2018 and 2019. AIDS, published online 8 February 2023.