(CNN) Authorities in Germany are investigating the birth of three children with hand deformities in a city in the west of the country.
The Sankt Marien Hospital in the city of Gelsenkirchen reported that three babies were born with "one-sided hand deformities" between June and the beginning of September this year.
"In two of the affected children, the left hand was deformed -- they had a normal forearm, but the palms and fingers were undeveloped. In another child, the right hand was affected -- here, too, the hand and fingers were undeveloped, despite a normal forearm," the hospital said in a statement.
The hospital said there were no "ethnic, cultural or social similarities" between the affected families that could explain the deformities, and it noted that all lived within the local area.
"We have not seen deformities of this kind for many years. Multiple occurrences could be a random burst. However, we believe that the brief period during which we have seen these three cases is striking," the hospital said.
Statistically, between 1% and 2% of all babies are born with a deformity, the hospital said.
The case was brought to light by Sonja Liggett-Igelmund, a midwife based in the western German city of Cologne, who has warned that many more babies may have been born with the same condition.
Liggett-Igelmund told CNN that she learned about the cases in Gelsenkirchen when talking to fellow midwives on online midwifery forums.
She said that while deformities such as these "do occur," they are typically "so rare," and seeing three similar deformities in the space of a few months was "too much."
"To me, it sounded like something much bigger," she said. "One midwife came across one case in her whole career. Three in three months is not normal."
Since bringing attention to the cases, Liggett-Igelmund said she has been contacted by many families across Germany whose children have been born with similar deformities.
"All the babies have the same deformities. Even colleagues have told me about such cases," she told the Süddeutsche Zeitung newspaper. "Roughly speaking, all the children have been born in the past three years, and many of them this summer."
Detecting trends in deformities among newborns in Germany isn't straightforward, as there is no national register. Liggett-Igelmund told CNN that creating a centralized register is vital.
The Sankt Marien Hospital noted that limb deformities during pregnancy can be caused by infections or toxins of various kinds.
Other possibilities, the hospital said, include constriction ring syndrome -- when fibers from the amniotic sac wrap themselves around a fetus, causing deformities -- or the umbilical cord becoming wrapped around a fetus' limbs.
The health ministry for the German state of North Rhine-Westphalia told CNN that it takes reports of deformities in children "very seriously" and intends to contact all medical centers in the state to determine whether similar deformities had been recorded.
"In addition, we are establishing contact with medical associations, the federal government and the other federal states in order to investigate possible causes with all due care," it added. "It must be examined together as to whether a registry is the right way forward."
The latest cases in Germany follow a similar cluster in isolated rural regions of France last year, which sparked a nationwide investigation.
In October 2018, the French health agency, Santé Publique France, found seven cases of limb deformity among newborns in three geographical areas, which had been flagged by the regional register for birth defects.
Additional tests conducted with hospital data in the Ain region, near the Swiss border, revealed a further 11 cases, amounting to a total of 18 cases between 2000 and 2014.
Agnès Buzyn, France's health minister, warned that the cases could be caused by an "environmental issue."
"It could be what they ate or what they drank. It could be something that they've breathed in," she told French TV station BFM TV.
The new cases in Germany are also reminiscent of the thalidomide scandal of the 1960s, when a drug created by the German pharmaceutical company Chemie Grünenthal to alleviate morning sickness caused thousands of women to suffer stillbirths. Many children who survived exposure to the drug in the womb were born with limb deformities.