Desparate housewives, only got into recently watching back copies. How has Gabby got children?

[CreamolaFoamless]

Although I am very very late to the party I am really enjoying this programme.

I've been watching the back episodes but it's gone from Gabby having no children and not able to get pregnant to then having 2 school aged children?

How did this happen , have I missed a couple of series or something that I can't find or was it just a continuity error and was never explained?

There was a 5 year jump in time between series. It is explained later in the series.

thank you .....which series does it get explained in 5?