The hospital delivered about 340 babies in June.
"Bombing a maternity hospital which is helping women living under the shadow of war to give birth safely is a shameful act, whether it was done intentionally or because due care was not taken to avoid civilian areas," said Sonia Khush, Syria director for Save the Children.
"There is no excuse, and unfortunately this is only the latest in a series of strikes on health facilities in Syria."
Syrian government air strikes put four makeshift hospitals and a blood bank in Aleppo out of action last week, according to local rescue workers. Perpetrators are not known.
Meanwhile, the Syrian Network for Human Rights has released a report on the aftermath of the cessation of hostilities agreed in February.
The NGO claims 5188 civilians have been killed and 3631 injured in the five months since then, and 71 per cent of all violations were committed by the Russian and Syrian regimes.
However, the Russian co-ordination centre in Latakia, Syria, blamed terrorist groups for what it said had been 841 violations of the agreement.