A pregnant woman and her daughter were killed Saturday by regime artillery fire on Syria's Idlib province, a monitor said.

Assad's forces have been amassing along Idlib's borders for weeks and shelling opposition-held territory on a daily basis, according to the Britain-based Syrian Observatory for Human Rights.

On Saturday near the city of Jisr al-Shughur, "a pregnant woman and her daughter were killed by these regime strikes", the Observatory said, reporting similar artillery fire in other opposition-held areas.

Experts say Jisr al-Shughur could be a key target if the regime and its Russian ally were to launch an offensive on the region.

Idlib is adjacent to Latakia province, the coastal heartland of Assad's Alawite minority and home to the Russian military airport of Hmeimim.

Idlib and the surrounding region have a population of approximately 3.5 million, and a substantial part of it consists of refugees who fled different parts of the country.

UNICEF said food, water, and medicine are already in short supply in the largely rural northwestern province, now home to millions of Syrians who have been displaced from their homes by regime offensives across the country.

So far, around 6 million people have been displaced internally and another 5 million were driven abroad as refugees since the beginning of the Syrian civil war, according to United Nations figures.

The civil war erupted in 2011 when the Assad regime harshly responded to protesters who had poured into the streets to demand more rights and freedom. The protests initially emerged following the Arab Spring demonstrations that resulted in strongmen in Egypt, Tunisia and Libya stepping down. The cruelty against protesters triggered into a rebellion in significant parts of the country, turning into a brutal civil war. So far an estimated 500,000 people have been killed in the war.