"I think there's a very good likelihood that he will lift the 'global gag rule,'" said Steven Mosher, head of the pro-life, non-profit Population Research Institute.
"The previous Democratic president Bill Clinton just a couple of days after being sworn in signed a whole series of executive orders which undid the policies of the previous two administrations," Mosher said.
First introduced by Republican president Ronald Reagan in 1984, the "global gag rule" cuts off US funding to overseas family planning clinics which provide any abortion services whatsoever, from the operation itself to counselling, referrals or post-abortion services.
When President George W. Bush came into office in 2000, he immediately reversed Clinton's orders once again freezing funds to many family planning groups.
US funds to the UN Population Fund (UNFPA) have been blocked since 2002, with the State Department saying the UN agency supports China's one-child policy, which is says amounts to coercive abortion.
"The Bush administration has said the UNFPA supports coercive birth control methods and that's why they're blocking money to it," said Tait Sye, a spokesman for the Planned Parenthood Federation of America (PPFA).
"The problem is that UNFPA money goes towards things like family planning and contraception, too," vital services in developing countries, he added.
A World Bank report published in July said women in developing countries, where access to contraception is poor, often turn to abortion as a means of birth control.
Abortion is more costly than providing contraceptive services, and around half the 42 million abortions performed annually are unsafe, the report said.
UNFPA senior culture adviser Azza Karam stressed at the launch of the UN agency's annual State of World Population report in Washington this week that family planning is "not a luxury of whether or not you're going to have premarital sex" but a service that women must have access to.
One woman dies every minute somewhere in the world because of complications during birth, she said.
The Obama transition team has not said what the president-elect intends to do when he takes office on January 20, but speculation is rife he may undo the gag rule.
"We think there's going to be a change, and clinics will be allowed again to offer a full range of family planning services," said PPFA head Cecile Richards.
Democratic lawmaker Carolyn Maloney drew applause when she told the launch: "We are about to see major cultural change in Washington ... One big change is that UNFPA will be funded."
Pro-lifers, however, said they would be gutted if Obama reversed the gag rule.
"We are appalled that Barack Obama is considering changing the policy," said Katie Walker, spokeswoman for the American Life League (ALL).
"The majority of Americans are horrified by the concept of abortion and that includes many types of hormonal contraception which operate by causing early abortion," she told AFP.
According to a survey conducted in May by Gallup, roughly 50 percent of Americans are pro-choice, for abortion rights, and around 40 percent are pro-life, opposed to abortion rights.
Mosher said he would be "personally distressed" if Obama were to reinstate funding for the UNFPA. "They're clearly, in our view, cooperating with China's one-child policy, which involves targets and quotas for abortions and sterilizations," he told AFP.
"We would like President Obama to weigh the evidence before he makes a decision."