The highest adolescent fertility rates occur in sub-Saharan Africa, at over twice the global rate, coinciding with the disproportionate burden of HIV among adolescent girls and young women. In 2020, there were more than 350,000 new HIV infections among adolescent girls and young women 15–24 years of age in sub-Saharan Africa, where over 50 per cent of pregnancies occur in young women. Adolescent mother-infant pairs are at elevated risk of poor outcomes across the PMTCT cascade, including an acute vulnerability to new HIV infections for pregnant adolescents not previously affected by HIV.