As mentioned by Veda Vyasa himself to Dhritarashtra, in Mahabharata Vana Parva 9.21
चिराय तव पुत्राणां शतमेकश्च भारत ।
पाण्डोः पञ्चैव लक्ष्यन्ते तेऽपि मन्दाः सुदुःखिताः॥२१॥
भारत ! दीर्घकालसे तुम्हारे एक सौ एक पुत्र हैं; किंतु पाण्डुके पाँच ही पुत्र देखे जाते हैं। वे भी भोले-भाले, छल कपटसे रहित हैं और अत्यन्त दुःख उठा रहे हैं ॥
Bharata ! Since long ago you have 101 sons, but Pandu has 5 sons. They are free from malice and crookedness and still they are going through this suffering.
Dhritarashtra had one son from Sughada who was Gandhari’s chief maid. The name of son was Yuyutsu (युयुत्सु)