(CNN)Dr. Lisa Haddad remembers the women's faces clearly.
Since 2008, the obstetrician-gynecologist has been traveling to sub-Saharan Africa. While working in Zambia, she saw gynecologic units in the hospital filled with women admitted with heavy bleeding or life-threatening infections, she said.
The women often would remain tight-lipped about why they were hemorrhaging, but Haddad said that it was clear to her and the Zambian clinicians what was happening. Some of the women had unsafe abortions and were facing serious complications, she said.
"This is a public health priority and I don't think it's been placed on that level and given the attention that it needs," said Haddad, associate professor in the department of gynecology and obstetrics at Emory University School of Medicine.
A new study finds nearly half of all 55.7 million estimated abortions around the world each year between 2010 and 2014 were performed in an unsafe manner, putting women at risk for serious complications.
The study, published Wednesday in the journal The Lancet, suggests that unsafe abortions are still a major health problem globally, especially in developing countries.
"These are the first global estimates to show the distribution of the abortions across three safety categories," said Dr. Bela Ganatra, a scientist at the department of reproductive health and research at the World Health Organization and lead author of the study.
"For the first time, we actually tried to determine the conditions under which abortions take place, how, who, where. This allows us to develop a better understanding of actions needed," she said.
Based on the WHO definition, an unsafe abortion results from a pregnancy that is terminated either by someone who lacks the necessary medical skills or in an environment that does not conform to minimal medical standards, or both.
Unsafe abortions can lead to complications, such as heavy bleeding, infection, damage to genitals or internal organs, or an incomplete abortion, such as when all of the pregnancy tissue is not removed from the uterus, according to WHO.
Complications related to unsafe abortions sometimes can be fatal.