Weird Pregnant Guppy Gravid Spot

[Cloudeia]

Hey guys,
So I have two pregnant female guppies, and both have fairly large gravid spots and have already squared off but will probably get a bit bigger. Anyways, in the morning their gravid spots are a translucent pink or orange, but as the day goes on, the gravid spot goes back to black like normal. Anyone know what's going on? Should I be worried about the fry?
Thank you!
Cloudeia

 

[SnailPocalypse]

Possibly pregnant?

 

[Snophi]

I dont have guppies but find that during the night my fish tend to lose the colour. I believe that this helps to save energy as they 'sleep'. Maybe the gravid spot is the last to gain their colour so it gets darker during the day?