It's normal in pregnancy due to hormonal changes in body. Try to be happy and feel that pregnancy is a blessing for you so feel good side of it. 

Take healthy diet and use prescribed multivitamins by your gynecologist. 

If you already have kids spent time with them specially when they are playing and enjoy those moments.

Spent time with your partner talk about your mood swings and ask him to support you emotionally. 

More you concentrate on negative behavior like aggression you will feel more aggressive. So try to divert your attention from these negative feeling by doing some physical activity.

Take proper sleep and even short naps during day time.

Drink plenty of water as well

Go for regular walk as it has very good effect on your physicl health during pregnancy  as well as on your psychological health.

But if you feel that your symptoms are moderate to severe than please consult any psychiatrist to overcome these symptoms.