If you just started playing you can reinstall the game. Please note: your progress will be deleted and you will start from the beginning and choose the baby you like. Baby data is backed up on iCloud so in order to change the baby need to disable the backup temporarily and then reinstall the game, choose a new baby and re-enable backup.
1) Go to Settings > General > Usage > Manage Storage > Choose your name
Under backup options choose the game (Baby Adopter) and switch from ON to OFF.
It will ask you to delete the backup.
2) Please delete it then after that you can uninstall and reinstall the game.
3) Choose the baby you like.
4) Go again to
Settings > General > Usage > Manage Storage > Choose your name
Under backup options choose the game and switch back from OFF to ON.
This step is important to have your baby data safe and backed up.