We adopted our daughter in March so her health insurance started in March. How do we avoid the penalty for her not having insurance before she was with us?

[ToddL]

If you adopted her in March 2017, then for purposes of your tax return she had coverage "all year". 

"All year" applies to the period of time that she was your adopted daughter. The same would apply to a newborn child - you can claim coverage for the entire year, even if the child was born in December.