That gestational carriers tend to be so altruistic by nature is not, as it turns out, by accident — they are carefully vetted that way, said Ms. Wippler.

Though the surrogacy industry remains loosely regulated by the federal government, it has come a long way since “Baby M.” Reputable agencies adhere to guidelines put forth by the American Society for Reproductive Medicine, or A.S.R.M. Applying these standards, along with those imposed by her own agency, means few applicants make it through the screening process. Out of the 300 to 400 candidates her agency receives each month, Ms. Wippler said, only 1 to 1.5 percent are accepted.

Candidates are disqualified for any number of reasons, the most common resulting from a health screening. A.S.R.M. guidelines say surrogates should be between 21 and 45 years old, have carried at least one child to term without major complications and maintain a healthy body-mass index. But the guidelines also require surrogates to undergo psychological screening — a process that closely examines a candidate’s motivations to pursue work as a gestational carrier.

Applicants who are deemed overly dependent on the compensation provided, including those who receive government assistance, are screened out as surrogates. “We always go back to a ‘do no harm’ mentality,” Ms. Wippler said, noting that if a candidate receives food stamps or Medicaid, the payment provided for surrogacy would in many cases cause them to lose eligibility for those benefits.

An applicant’s family members are also screened to ensure they are supportive. Aretha Cagno said her husband and children — who are 12, 9 and twin 6-year-olds, plus a baby due next month — have from the beginning been “100 percent supportive” of her work as a surrogate. As is fairly common in surrogacy arrangements, her family has grown close to the man she carried for and the two resulting children, a 2-year-old and 11-month-old. She noted that the families would get together in person frequently before the pandemic.