Imam al-Shafi'i (may Allah have mercy on him) said: "The sixty (camels) that go along with the forty pregnant she-camels will be: thirty hiqqah (three-year-old she-camels) and thirty jadha'ah (four-year-old she-camels)."
He narrated this from some of the Companions of the Prophet (peace and blessings be upon him) (may Allah be pleased with them), and in another place he narrated it from Sayyiduna Umar bin al-Khattab (may Allah be pleased with him).
Sayyiduna Umar (may Allah be pleased with him) said: The aggravated blood money (diyah mughallazah) is 30 hiqqah, 30 jadha'ah, and 40 that have young in their bellies, and this is the blood money for quasi-deliberate killing (shibh al-'amd).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الديات / 16121