National HIV screening in pregnant women in the Netherlands is effective
Colette Smit, Stichting HIV Monitoring
Since 2004, all pregnant women in the Netherlands are tested for HIV. Through the timely diagnosis of HIV it is possible to treat women early in pregnancy with effective HIV medications. This reduces the risk of mother-to-child transmission of HIV. Since the introduction of screening, the number of children born with HIV in the Netherlands has fallen sharply.
HIV-transmission
The transmission of HIV from an HIV-infected mother to her child is the most common route of HIV transmission in children worldwide (1). Mother-to-child transmission can occur before birth, during delivery and postnatally during breastfeeding. Without intervention the risk of HIV transmission varies between 15 to 20% (2). Effective HIV medication (cART) is very effective in the prevention of mother-to-child HIV transmission. Since the introduction of cART in the treatment of HIV-infected pregnant women, transmission has been drastically reduced to 2% (3,4).
Knowledge of HIV status during pregnancy is essential for the timely start of cART in pregnancy and thus also for the reduction of HIV transmission. For that reason, voluntary HIV screening in pregnant women was introduced in the Netherlands in 2004. Screening is carried out using the opt-out principle, which means that it is standard to test each pregnant woman for HIV unless they actively refuse. Before the introduction of national screening in 2004, a selective HIV screening method was used, aimed at women with a higher risk of HIV, such as women from an HIV endemic area or with (former) injecting drug use. Since national screening was introduced, 233 women with an unknown HIV infection have been diagnosed and reported to Stichting HIV Monitoring (SHM) (5).
Number of pregnant women with HIV
During the period 1996-2012, 1,734 pregnancies among 1,114 HIV-infected women were reported to SHM. A total of 4,016 women are monitored by SHM. Amongst pregnant women, 54% were diagnosed with HIV prior to the onset of pregnancy. During pregnancy, 99% of women were treated with cART.
Mother-to-child transmission in the Netherlands
The number of children born in the Netherlands and infected via mother-to-child transmission has decreased significantly since 2004 (Figure). This decrease is attributable to the introduction of the national HIV screening (6). Following the introduction of national screening in 2004, six HIV-infected children have been born in the Netherlands. Although the number of children with HIV born in the Netherlands has fallen sharply, mother-to-child transmission can not be completely eliminated. It is possible that HIV infection sometimes occurs after screening, which usually takes place in the first trimester of pregnancy. It may also be possible that screening takes place shortly after the time of infection, so that the result of the HIV test is still negative.
The national prevalence of HIV among pregnant women is very low (0.04-0.08% (7)). As a result, a second national screening during pregnancy is probably not very effective. A second screening could possibly be based on a risk assessment if, for example, the partner is known to be HIV-positive (7).
Figure: Number of Hiv infected children, infected by mother to child transmission, according to their year of birth and stratified by region of origin.
Reference List
(1) UNAIDS. Report on the Global AIDS epidemic, http://www.unaids.org/en/knowledge/HIVdata/globalreport/2008/2008_global_report.asp. 2008.
(2) Coll O, Fiore S, Floridia M, et al. Pregnancy and HIV infection: A european consensus on management. Aids 2002 Jun; 16 Suppl 2:S1-18.
(3) Boer K, Nellen JF, Patel D, et al. The AmRo study: pregnancy outcome in HIV-1-infected women under effective highly active antiretroviral therapy and a policy of vaginal delivery. BJOG 2007 Feb; 114(2):148-55.
(4) Cooper ER, Charurat M, Mofenson L, et al. Combination antiretroviral strategies for the treatment of pregnant HIV-1-infected women and prevention of perinatal HIV-1 transmission. J Acquir Immune Defic Syndr 2002 Apr 15; 29(5):484-94.
(5) van Sighem A, Smit C, Gras L, et al. Monitoring of Human Immunodeficiency Virus (HIV) Infection in the Netherlands. Amsterdam: Stichting HIV Monitoring; 2012.
(6) Boer K, Smit C, van der Flier M, de Wolf F. The comparison of the performance of two screening strategies identifying newly-diagnosed HIV during pregnancy. Eur J Public Health 2010 Nov 4.
(7) Op de Coul EL, Hahne S, van Weert YW, et al. Antenatal screening for HIV, hepatitis B and syphilis in the Netherlands is effective. BMC Infect Dis 2011 Jun 30; 11(1):185.