Datillo's commander Capt. Alessio Morelli said the mothers were among the 1,004 migrants - most of them Eritrean and Nigerian - rescued north of Sabratha, Libya. Once aboard, they gave birth "so we went from 1,004 to 1,007, two baby boys and one baby girl."
The Datillo pulled into port in Catania, Sicily today.
Also today, Italy's coast guard reported that another 28 bodies were recovered during rescue operations a day earlier that saved 4,655 people. The operations followed the recovery of 10 bodies when more than 6,000 would-be refugees were picked up on Monday, according to the International Organisation of Migration.
A police statement said today one vehicle carried 34 migrants from Afghanistan and Pakistan, and another had 37 people from Afghanistan, Pakistan, Iraq and Iran. The two drivers were detained and face criminal charges.
Serbian officials have vowed to step up military and police patrols on the borders with Bulgaria and Macedonia to stem the continuing influx of migrants.
The Balkan route, used by nearly 1 million migrants last year to cross to mainland Europe, was closed in March. Since then, hundreds still try to enter illegally daily in an attempt to reach the EU. An estimated 6,000 migrants are stranded in Serbia after Hungary further tightened its borders this summer.