Mr Justice Coleridge said there was evidence that women were going to Nigeria seeking fertility treatment, then being sold unwanted babies.
They had been tricked into thinking they had become pregnant and given birth, he said.
The judge said there was more than one case with “almost identical facts”.
Mr Justice Coleridge said one “truly worrying” case involving a Nigerian couple from London gave rise to “very real public interest, particularly the lack of involvement by the Nigerian authorities”.
The mother said she was tricked by a doctor into believing she had given birth at a clinic in Port Harcourt, Nigeria, in January 2011, while sedated, after she went to Nigeria for fertility treatment.
In his written ruling, which he released earlier, the judge said the couple were members of a charismatic church and had a “strong faith and belief in the power of prayer”.
The woman was “immersed in a Christian religious environment where miracles are not regarded as impossible,” he said.
“All the mother’s actions, in my judgment, both in this country and Nigeria, are consistent with her evidence that she had no idea she was involved in this strange scam, designed to put together unwanted children with desperate, childless parents.