Deaths from pregnancy and childbirth down 45 percent since 1990

The United Nations reported on Tuesday that the amount of women dying during pregnancy and childbirth is down 45 percent since 1990.

An estimated 523,000 women died in 1990 due to complications related to pregnancy. That number fell to 289,000 by 2013.

Sub-Saharan Africa is the deadliest place in the world for expectant mothers.

"A 15-year-old girl living in sub-Saharan Africa faces about a 1 in 40 risk of dying during pregnancy and childbirth during her lifetime," Dr. Geeta Rao Gupta, the deputy director of UNICEF, said. "A girl of the same age living in Europe has a lifetime risk of 1 in 3300, underscoring how uneven progress has been around the world."

Another study released Tuesday by the World Health Organization reported that 1 in 4 maternal deaths are caused by pre-existing conditions, including HIV and malaria.

"Ending preventable maternal deaths will require both continued efforts to reduce complications directly related to pregnancy and more of a focus on noncommunicable diseases and their effect in pregnancy," Dr. Marleen Temmerman, the co-author of the study and WHO's director of reproductive health and research, said.

Both WHO and the U.N. called for improvement in how data regarding maternal deaths is collected. The U.N. Commission on Information and Accountability for Women's and Children's Health will require all countries to establish a means of recording maternal deaths by 2015.