Hi , 
How are you doing ?
These medicines are to control the psychiatric problems. 
All three drugs do cause defects in the newly formed baby, these defects are usually multiple & not correctable. 
Carbamazepine can cause - 
Spina bifida, craniofacial defects, cardiovascular malformations, 
hypospadias, and anomalies involving various body systems. 
But instead of this combination, if used alone, this can be safer
Lithium can cause - heart defect, sudden death of baby etc better avoided in pregnancy
Arip MT is contraindicated in pregnancy, only animal studies are available.
So if I may advise, kindly consult your 
Neurologist & change over to less toxic drugs , reduce the dosage gradually under supervision & if possible switch to single drug. Once all stabilized pregnancy will be okay. 
This can avoid all the unnecessary 
anxiety with the medicines with known teratogenicity.
  Hope I have clarified your query, do write back if any more queries
All the best
Dr.Balakrishnan