The little girl, just seven months old, died in hospital.
In serious condition, she had been admitted to the Lille hospital center on the night of Friday to Saturday this weekend.
An investigation is open and the autopsy is underway.
According to information from France 3 Hauts de France, three people were arrested and placed in police custody on Saturday.
Among them, two men aged 24 and 39 and a woman, the mother, aged 24.
The mother and the 29-year-old man were both released without charge.
The companion of the young woman, meanwhile, was indicted for "intentional homicide".
Suspected of having committed violence on the infant, he was remanded in custody on Monday evening.
At this time, the track of the "shaken baby" syndrome is mentioned.
According to the nursing staff present on the spot that evening, the infant presented several symptoms.
If the results of the autopsy are not yet known, the investigators have already acquired the certainty that the little girl had not died of natural death.
A deadly abuse
Each year, around 200 infants are victims of this type of abuse, according to figures from the “Stop Bébé Shaken” association.
The Ministry in charge of Children and Families also launched a prevention campaign last January with the aim of raising awareness of the consequences of these acts on toddlers.
“Every day in France, 1 baby is a victim of shaken baby syndrome.
In 1 out of 10 cases, he will die.
If he survives, he will have serious consequences, ”insists the government.
The act, which takes just a few seconds, will indeed have a lasting impact on the development of children.
Abused babies will have serious consequences for life: motor handicaps, epileptic seizures, cognitive disorders and learning difficulties, behavioral problems... The brain damage caused by the shock is irreversible.
