The charges relate to valproate, a drug marketed as Depakine among other trade names, which studies say caused disabilities in about 15,000 to 30,000 children whose mothers took the medicine.
French prosecutors have indicted pharma giant Sanofi for manslaughter over birth defects linked to an epilepsy drug in a long-running case that has also seen the company charged with fraud.
The charges relate to the drug valproate, marketed as Depakine among other trade names, which studies say has caused disabilities in about 15,000 to 30,000 children whose mothers took the medicine while pregnant.
The research found that when pregnant women took the drug, their children had an elevated risk, between 10 to 40 percent, of congenital malformations, autism and learning difficulties.
Sanofi is facing separate charges of aggravated fraud and unintentionally causing injury in 42 cases filed by families, but insists it had warned health authorities of the drug's risks already in the 1980s.
On Monday, the company confirmed a report in Le Monde newspaper that prosecutors have now also charged it with manslaughter.
But in a statement sent to AFP, it insisted it had "fulfilled its obligation" of providing information on the drug and its side-effects, and said it "contests the validity of these proceedings."
Sanofi said it has filed a legal challenge to the indictment.
Under the French legal system, charges do not automatically result in a trial as prosecutors can decide not to proceed based on a lack of evidence.
Last month, a French court ordered the state to pay thousands of euros in damages over the scandal, saying officials should have ensured the drug was not taken by pregnant women.
The court found that health officials knew about the risk of birth defects from Depakine already in 1983, and of learning disabilities and autism from 2004.
Another 500 complaints have been lodged with France's national compensation agency for medical accidents, which has already proposed a $7.6 million (6.5-million-euro) package for Depakine victims.
Sanofi, a France-based multinational, is working on a candidate vaccine against the novel coronavirus with Britain's GSK, for which it will receive up to $2.1 billion from the US government.
To #FightCOVID19, we have partnered with @GSK to make a vaccine available globally. Today we announce an agreement with the US government to accelerate the development of a #COVID19 recombinant protein-based vaccine:#SanofiActs— Sanofi (@sanofi) July 31, 2020