i had the same problem when i had my daughter i had very curls hair, it went very kinky and lost a lot of the curl, with my son it came back a little (my hair has also gone alot darker i used to have a nice red hair now its brown) now im due a baby in 14 days and its turning to kinks again, all my children have my red hair and curls. but i used to only wash my hair in body shops jajoba shampoo and the dont do it anymore maybe its using bad shampoo