Question Summary:
Is there any Islamic basis for this? Are there other days/dates that should be avoided for physical relationship between couple?

Question Detail:

When trying for a child, I have heard that there are certain dates that should be avoided for intercourse.  For example the 14th, 15th and 16th of the Islamic months should be avoided in order to have a healthy baby.  Is there any Islamic basis for this?  Are there other days/dates that should be avoided?

Jazak'Allah Khair

Answer :

In the name of Allah, Most Gracious, Most Merciful
Assalaamu `alaykum waRahmatullahi Wabarakatoh
There is no Islamic basis for avoiding intercourse on certain days to have a healthy baby 
And Allah knows best
Wassalam
Mufti Ebrahim Desai
Darul Iftaa, Madrassah In'aamiyyah