How can I control the space between layout and widgets inside a parent layout?

I have a QVBoxLayout. Inside there are a QLabel and a QGridLayout and another QLabel. As the widget start everything works fine. but when I change the widget size - QT put the all additional vertical space before and after the QGridLayout.

I think it happens because QVBoxLayout act towards the QGridLayout as if it is just another widget. So QVBoxLayout keeps same space between the three widget it has: QLabel, QGridLayout and QLabel.

My Question is: How do make it react to the widgets QGridLayout hosts? so I will have even spacing between all the widget in the form?

Thanks
Dave