I Feel Like It Is Negligence On The Part Of The Doctor

At the time when I got my 6 months wife sonographed the doctor said everything is alright and there is nothing to worry however when the baby girl was born, she was recognised with a deformity called cleft lip and palate on her face. All my family members and the other hospital team where the child delivery was done were shocked and I was asked by this other hospital staff that did the doctor not tell you about the deformity at the time of 6 months sonography, and my answer was of course No. It has been 1 month since the baby was born and this hasn't been easy to take care of the baby and also we are facing lots of mental trauma, I hope you can empathise the same while reading this. Now, what action can be taken against the sonography doctor, who did not tell us about this issue as it seems to me like he was being negligent? Thank you.