The war in Syria began in 2011 with harsh repression of protests.
More than 600 people are in need of urgent medical care, according to SAMS.
Eastern Ghouta is mostly under the control of Jaish al-Islam rebels.
The Observatory relies on a network of sources inside Syria and says it determines whose planes carry out raids according to type, location, flight patterns and munitions used.
The United Nations has made repeated calls for warring parties to abide by their responsibility to protect children in line with global humanitarian and human rights law.
Government and allied forces backed by Russian warplanes have been battling militant fighters and rebels for more than a week in an area straddling the boundary between Idlib and Hama provinces.
Eastern Ghouta has been targeted despite being among a handful of so-called de-escalation zones in Syria, where military activity is prohibited under a ceasefire agreement endorsed by Turkey, Russia, and Iran earlier this year.
At least four bombs flattened two buildings in the Eastern Ghouta town of Misraba, in an attack that killed around 20 and wounded more than 40 people, the Syrian Observatory for Human Rights and civil defense sources said.
He said, however, that Russian daily Kommersant's article reporting that seven Russian planes were destroyed in the attack was "fake news".(ANSAmed).
Russian media have reported that a deadly December 31 rebel mortar attack on an airbase in Syria destroyed up to seven Russian warplanes.
Moscow acknowledged in recent months that its special forces are also active on the ground in the offensive against the Islamic State group.
The Ministry of Defense pointed out that on December 31, at sunset, the military installation in Latakia province was attacked by a mobile group of fundamentalists, but the operational capacity of its air units was not affected at all.