The UN children's agency said they and Pakistani government officials assessed the situation in the worst-hit districts of mountainous Baluchistan province and were "concerned about the urgent needs of children and women".
Up to 300 people are thought to have been killed in the 6.4-magnitude quake, which struck before dawn on Wednesday, flattening mud-brick houses and killing or injuring people as they slept.
"With winter closing in, the most urgent needs of the survivors are shelter, safe drinking water, food, warm clothing and emergency medical assistance," the world body said in a statement.
Clean water was a "priority" and UNICEF teams had started providing water and sanitation services, and food supplements for pregnant women and young children, it said.
"Children are especially vulnerable to diseases such as diarrhoea and cholera," it added.
"Most of the water sources in the affected districts have been damaged by the earthquake. Approximately 12,000 people in Ziarat lack safe water and are dependent on supplies from water trucks."
The district health officer of the stricken hill town of Ziarat, Ayub Kakar, told AFP that children were already suffering after two nights in the open in sub-zero temperatures.
"Due to the cold hundreds of children are being treated for pneumonia, abdominal diseases, diarrhoea and chest problems," he said.
"We fear the death toll will rise. Such diseases, if not treated in time, are life-threatening," Kakar said.
Tents, blankets, clothes, medicine and antibiotics were still in short supply, he said. Many people in outlying villages have expressed concern that they have gone without help more than two days after the disaster.
"Our children are dying, help us," cried Mohammad Khan, in the village of Khanozai high in the mountains.
Kakar said children formed the majority of the population in the quake-affected area and many of them were psychologically affected by the tremors, and violent aftershocks that continue to pound the region.
Women were also not getting medical treatment because of deeply conservative traditions and the fact that hospitals were also hit.
Pakistan's military says it had provided tents, blankets and food to 25,000 affected people in the devastated villages of Wam, Tungi and Gogi, with another 15,000 set to get relief goods later Friday.
"Nobody will be without tents, blankets and food rations today," Major Khan Mohammed of the paramilitary Frontier Corps told AFP.
Colonel Shahzada Khan said the International Committee of the Red Cross, one of a number of international NGOs in the relief effort, including the World Food Programme and World Health Organisation, had sent 5,000 relief kits.
Each kit consists of one tent and 15 days' rations for a family of five.
"An aerial survey is still being conducted by helicopters in far-flung areas to locate the affected people," said Shahzada, also from the Corps.