What are the chances of having 2 children with down syndrome in statistics? and would that disqualify someone from donating an egg for someone ivf?

Depends on situation: Recurrence risk for traditional 21 trisomy ds is 1% plus any age related risk. If the 1st offspring has a translocation ds (2%) which is extra 21 material derived from a balanced carrier parent, it could be quite high.Standards for ivf donation are set by the centers involved and encompass many health and medical history factors.Contacting that center would be necessary to answer such a question.

Probably would: It would be unlikely someone with 2 downs pregnancies would be accepted as an egg donor.

Age and karyotype: Having one child affected is age-specific unless there is a family history. Under 35, after one randomly affected fetus, the risk is 1%, about the mid-term risk of a 40 year old. 4% of all affected have a translocation-a 21 attached to another chromosome. A dad who is a carrier has around 5% risk, and a mom between 10-15% risk--unless either has a 21-21 translocation. Then the risk is 100%.