United Nations Fund for Population Activities (UNFPA)'s initial estimates indicate some 50,000 pregnant women and girls could be among the survivors.
Pregnant women affected by the disaster require maternal health services, including antenatal care, safe delivery services, post-partum care, and, for those who experience complications, emergency obstetric services, it said.
Protections for women and girls from gender-based violence and other threats will also be critical, said the UN agency.
"Many women lose access to essential reproductive health services and give birth in appalling conditions without access to safe delivery services and lifesaving care," she said.
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UNFPA is coordinating with the Government and humanitarian partners to respond to these needs. Emergency staff members are being deployed, and dignity kits and reproductive health kits are en route to Nepal.
"The Fund is particularly concerned about the fate of pregnant women who have been affected by this tragedy, including those who might face potentially life-threatening complications," said UNFPA Executive Director Dr Babatunde Osotimehin, in a statement on the disaster.
According to the United Nations, the massive earthquake in Nepal has affected eight million people, more than a quarter of the country's population.