If your child was born in 2017 and the child qualifies as your dependent, you should have indicated on your tax return that the child lived with you 12 months during the year. If you did not, and your return was accepted by the IRS, then you should amend to correct that on your return as it could affect the tax credits that you may be eligible to receive.
Please
see the following TurboTax FAQ for
instructions on how to amend your 2017 tax return in TurboTax.
https://ttlc.intuit.com/replies/3288565
