Pregnant girls aged between 15 and 19 account for 70 000 of the 500 000 deaths related to childbirth complications worldwide.
Unicef executive director Ann M Veneman revealed these findings at the launch of the 2009 "State of the World's Children" report at the Hilton hotel in Sandton on Thursday.
Veneman said the young girls' deaths could be attributed to early pregnancy.
Since 1990, complications related to pregnancy or childbirth had resulted in the death of an estimated 10 million women around the world.
Veneman pointed out forced marriages made young girls vulnerable to contracting HIV/Aids and sexual abuse.
However, health minister Barbara Hogan said forced marriages were not a big issue in South Africa but early sexual activity was. - Sapa