Idlib province and some adjacent areas form one of four so-called de-escalation zones agreed in May by Turkey and government allies Russia and Iran.
Front lines across the province had been relatively quiet since then but intense fighting erupted on Tuesday, the Syrian Observatory for Human Rights said.
Extremist factions led by a former Al-Qaeda affiliate, which are not included in the de-escalation deal, launched a fierce assault on a string of regime-held villages along the border between Idlib and Hama province.
“An hour later, the regime launched airstrikes on the operation’s supply lines. Raids are now ongoing across southern Idlib province and northern parts of Hama province,” said Observatory head Rami Abdel Rahman, adding that Russian warplanes later joined in.
Syrian raids hit a maternity hospital in the village of Al-Tah and a medical outpost in the town of Khan Sheikhun, as well as near two other hospitals in Idlib province, said Abdel Rahman.
“The raids on the maternity hospital in Al-Tah killed an elderly woman who was an employee of the hospital, in the first civilian death in airstrikes in Idlib province since May,” he added.
“The attack and airstrikes are the most intense in the area since the de-escalation zone was announced in May,” Abdel Rahman said.
According to the medical charity UOSSM, which has provided equipment to the maternity hospital, the woman killed was a cleaner in the facility and other medical staff were wounded.
In a statement distributed to journalists, the charity said two sets of strikes hit the maternity hospital, setting fuel storage tanks on fire and leaving its incubator room “totally destroyed.”
UOSSM slammed the strikes and warned that “systematic attacks on hospitals are back despite de-escalation deals.”