For legions of Americans craving a chance to adopt children, a confluence of daunting trends makes this an especially distressing time.

The overall number of U.S. adoptions has dropped significantly in recent years, straining the viability of many adoption agencies and drawing some into conduct that authorities describe as unethical.

Would-be adoptive parents confront the specter of long waiting times and high fees. And many face pressure to spend lavishly on self-promotional advertising if they want to compete for a chance to adopt an infant.

Chuck Johnson, CEO of the National Council for Adoption, estimates that 1 million families are trying to adopt at any given time.

“No matter where they go, unless they’re super lucky, they’re going to be in for a long wait,” Johnson said. “They’re going to be in a slow, painful process for foster care or in this massive competition for the limited number of healthy infants — and that’s where the situation is ripe for fraud. There are so many families who want to adopt, and so few options for them.”

Some of the people desperate to adopt fall victim to scams. In March, for example, a woman from Carolina Beach, N.C., was accused of using the internet to fleece a dozen would-be adoptive parents.

In the absence of comprehensive federal figures, Johnson’s council, which represents more than 120 adoption agencies, periodically tries to tally the total number of adoptions in the U.S. Its latest count, released in February, showed a 17 percent drop from 133,737 adoptions in 2007 to 110,373 in 2014.

Most of the decline was due to a sharp decrease in the number of international adoptions; the number of infant adoptions remained relatively stable at about 18,000, as did adoptions out of foster care at about 50,000.

Thousands of clients seeking to adopt have been buffeted recently by the downfall of their agencies.

The State Department, alleging extensive improprieties in handling international adoptions, shut down Ohio-based European Adoption Consultants in December. It operated in a dozen foreign countries.

A few weeks later, a domestic-adoption agency licensed in eight states, the Independent Adoption Center, declared bankruptcy, leaving more than 3,000 clients in the lurch. The agency blamed the bankruptcy on “societal changes” that increased the number of parents seeking to adopt while shrinking the pool of expectant mothers open to having their babies adopted.

Among those affected were newlyweds Christopher Koontz and Bobby Duong of Long Beach, Calif., who said they had paid the agency about $16,000 over nearly two years. The extent of any reimbursement is uncertain.

“Several of our close friends, family members and co-workers were rooting for us to adopt — it felt shameful to tell them what happened,” Duong said.

Josh Christian, a lawyer in Greenville, S.C., was a client of European Adoption Consultants. He estimates that he and his wife ended out paying $10,000 extra to complete the adoptions of two sisters from Uganda, who had to spend more time in an orphanage because of the agency’s shutdown.

Only after the State Department action did Christian learn that there were long-simmering problems with European Adoption. He suggested there should be some sort of national database through which would-be adoptive parents could access information of that nature.

European Adoption was accused by the State Department of charging excessively high fees, misrepresenting information about children and other improprieties. The agency said it considered the shutdown unwarranted and was considering an appeal.

Many agencies specializing in international adoptions have closed in recent years, and others have struggled, as foreign adoptions by Americans have dwindled. The latest federal figures, for the 2016 fiscal year, reported 5,372 adoptions from abroad, down from a high of 22,884 in 2004.

There are many reasons for the decline — including an increase in domestic adoptions in China, Russia’s suspension of adoptions by Americans and corruption scandals that shut down international adoptions in several countries.

Virginia-based America World Adoption, which has offices in 21 states, has seen its caseload drop by more than 50 percent over a decade — from 447 international adoptions in 2005 to 208 last year.

“We have fewer staff now, and adoptions are becoming more difficult, taking longer,” said Ryan Hanlon, the agency’s executive director. Hanlon said some families lose interest when told that infants are not available. Those who do persist face large bills; adoptions from China or Ethiopia can cost $30,000 to $40,000.

One of the largest U.S. agencies, Bethany Christian Services, continues to grow overall even as the number of adoptions it facilitated dropped from 1,980 in 2010 to fewer than 1,300 in 2016. It has expanded other services in the U.S., including foster care and family counseling, and has launched programs in South Africa, Ethiopia and elsewhere to encourage foster care and adoption of orphans in their home country.

In San Antonio, Abrazo Adoption Associates was handling a peak of about 70 adoptions annually a decade ago and now fewer than half that number. Its executive director, Elizabeth Jurenovich, bemoans the cut-throat competition for the small supply of healthy infants — she calls them “Gerber babies” — available for adoption.

“It sticks in my craw that there are tens of thousands of American children sitting in foster care who are considered less than desirable because they’re no longer infants,” she said.

Of the roughly 50,000 children adopted from foster care annually, most are 5 or younger. Of the nearly 112,000 children left in the system still waiting to be adopted, most are 7 or older, according to federal figures.

Experts doubt the number of adoptions in the U.S. will ever approach their peak of 175,000 in the 1970s. One key factor: the destigmatization of single motherhood.

Deborah Siegel, a professor of social work at Rhode Island College, said the lower numbers aren’t necessarily a cause for regret.

“If we can avoid adoption by keeping children embraced in stable, safe families, everybody’s better off,” she said. “But that’s hard for the people waiting to adopt.”