Nearly half of the 46 countries in sub-Saharan Africa have had either stable or worsening child mortality rates since 1990, the report said. Only three - Cape Verde, Eritrea and the Seychelles - are on track to meet the 2015 child survival goal.
"It is a region of the world we have to concentrate on, but we also look at it country by country," Veneman said.
There has been "tremendous progress" in some African states - including Ethiopia and Malawi - which have reduced child mortality by 40 percent since 1990, she said, though others emerging from conflict have stalled.
Civil war-ravaged Sierra Leone has the world's worst ranking for under-five mortality, with 270 deaths per 1,000 live births.
Children in the developing world are frequently killed by respiratory or diarrhoeal infections that no longer threaten lives in rich countries. Many also die from measles and other diseases that can be prevented through vaccines, and suffer as a result of unsafe water and poor sanitation.
Simple, affordable measures such as breast-feeding, vaccinations and insecticide-treated bed nets can dramatically reduce child deaths, according to UNICEF.
"Having a healthy child with an opportunity to survive starts with the health of the mother. So is the mother getting prenatal care and proper nutrition?," Veneman said.
"If we're going to save children's lives, we have to make sure that they are healthy at birth," she added.
Veneman said it was critical to provide sustainable basic health care for pregnant women and children.
"You need a community-based system to provide the immunisations, the vitamin A supplementation and bed nets. You can provide these in an integrated package at the community level," she said.
