I am married since 5 months and we have been trying to have a child without success. If my husband, a physician, has work obligations after Maghrib, can we break the fast with intimacy for the purpose of childbearing on the day when I know I am ovulating?
As important as your husband's career may be, it cannot be more important than obeying Almighty God or having children. I am sure he is somehow able to adjust his working schedule during the holy month to be able to see you, and try to work around your ovulation time. He can get some time off work during the night, for whatever reason, even if it's unpaid leave.
However, you must both know that it will be haram and sinful for him or you to break your fast for this purpose, and the worst case scenario is for him is to either take a night off, or wait until after the ending of the holy month.
You are certainly a noble believer, and hence you ask this question, but if you break your fast for such an invalid reason, this guilt will always be with you, so it is always best to abide by the shar'i requirements and always have hope in Allah ta'ala who will accommodate for all our needs, all in due time.
With prayers for your success.