(CNN)France has launched a nationwide investigation into abnormal rates of babies born with missing or malformed limbs in several regions after 11 new cases were identified.
In October, the country's health agency, Santé Publique France, presented seven cases in three geographical areas that had been alerted by the regional register for birth defects, Remera.
Additional tests conducted with hospital data in the Ain region, near the Swiss border, revealed more suspect cases, totaling 18 over 15 years from 2000 to 2014.
For now, the cause remains unknown, Health Minister Agnès Buzyn said.
"It could be an environmental issue. It could be what they ate or what they drank. It could be something that they've breathed in. I don't know," Buzyn told French TV station BFM TV.
Pesticides are suspected to be to blame for the deformities, with the particular products likely to no longer be on the market, Emmanuelle Amar, director of Remera, wrote in an email. She added that this is based solely on assumptions for now.
"These cases occurred at a given time and then they stopped occurring," she said. "Either that the product used is no longer being used, or that the person or entity that was spreading it has now stopped spreading it."
The French health agency said that at this point, there is nothing that points toward a common cause.
The first step will be to evaluate, among the 11 suspected cases, those that correspond to transverse agenesis (the failure of the limbs to fully develop) of the upper limbs, Santé Publique said in a statement.
All cases will then be analyzed, and teams across multiple organizations will investigate what the affected families have in common.
"This large number of cases of infants with deformities, babies who have no arms, also exists in Brittany and Loire Atlantique," Amar said in a statement. "But there was only the report of those in Brittany that was taken into account by Public Health France."