Do understand your position. You cant expect a child to behave like an adult. At times the child gets irritated and throws tantrums towards parents. Though its not accepted behavior, the parents has to change their approach towards a child and help him to change.
The behavioral issues has connect with the child's pregnancy and environment. Probably due to pregnancy related concerns too.
The information you provided is quite vague, so gave the general suggestion.
Next Steps
Change your approach and see the response.
Health Tips
1) Use positive words only (2) Engage the child with new activities and challenges (3) Speak the language of a child