"It is a setback for women's freedom, particularly for those in the most precarious position who do not have the means to go to another state" to get an abortion, he told AFP in an interview.
Last week Wyoming became the first US state to outlaw the use of the abortion pill.
It was the latest point marked for conservative anti-abortion activists in the United States after the Supreme Court overturned the constitutional right to the procedure last year, leaving the policy to individual states.
Baulieu said he had dedicated a large part of his life to "increasing the freedom of women," and the ban was a step in the opposite direction.
Born in Strasbourg in 1926 to Jewish parents, Baulieu was raised by his feminist mother after his father, a doctor, died when he was a boy. At the age of 15, Baulieu joined the French resistance against Nazi occupation.
He went on to become a self-described "doctor who does science," specializing in the field of steroid hormones.
Invited to work in the United States, Baulieu was noticed in 1961 by Gregory Pincus, known as the father of the contraceptive pill, who convinced him to focus on sex hormones.
Back in France, Baulieu designed a way to block the effect of the hormone progesterone, which is essential for the egg to implant in the uterus after fertilization.
"I wanted to make a contragestive," which stops gestation, he told AFP.
Partnering with the French Roussel-Uclaf laboratory, the oral drug RU-486, also known as mifepristone, was developed in 1982, providing a safe and inexpensive alternative to surgical abortion.
But there was a long battle for the drug to become authorized in the United States, where anti-abortion activists dubbed it the "death pill".
'Fanaticism and ignorance'
In early March, French President Emmanuel Macron praised Baulieu's resilience when he presented the scientist with the Grand-Croix de la Legion d'Honneur, the top rank in France's honors system.
"You, a Jew and a resistance fighter, you were overwhelmed with the most atrocious insults and even compared to Nazi scientists," Macron said.
"But you held on, for the love of freedom and science."
Baulieu's wife Simone Harari Baulieu, a media producer in France, said "adversity slides off him like water off a duck's back".
She added that the recent "step backwards" in the United States was propelled by "fanaticism and ignorance".
Even at age 96, Baulieu heads into his office at the Kremlin-Bicetre University Hospital in the southern suburbs of Paris three times a week.
Stacks of photos, diplomas and binders contain "the work of a lifetime," the scientist said, adding that he still wants to "be useful".
His latest award is pinned to his blue suit, but Baulieu said he "never seriously hoped to receive such honors".
"It was a pleasure, but what interests me is improving people's health."
'Driving force'
The team in his lab are continuing research he began years ago aiming to prevent the development of Alzheimer's disease, as well as treatment for severe depression, for which clinical trials begin in the coming months.
Baulieu said "there is no reason we cannot find treatments" for both illnesses, which have stubbornly evaded many previous attempts.
Julien Giustiniani, the team leader at the Baulieu Institute, which was created to finance research into dementia, said Baulieu was "always enthusiastic".
"He is a driving force for us," Giustiniani said.
Though Baulieu now uses a cane to walk, he exudes a tireless energy.
He partly credits using DHEA, a natural hormone produced by the adrenal gland, which Baulieu first described in the 1960s and has been touted as an anti-ageing supplement.
The causes that have dominated his life were "women, brain health and longevity," Baulieu said.
"I would be bored if I did not work anymore," he added.
© Agence France-Presse
