'Potter Line' theory problem

[ingachristsuperstar]

No: HPFGUIDX 46003

OK, I've always been partial to the idea that Voldie was going 
after the "Potter Line" in total because he believed they posed 
him some kind of specific threat (as the descendents of 
Gryffindor or otherwise).  I've liked it because it explains a lot of 
the 'loose ends' floating around the series, like why LV was 
willing to spare Lily.

But I just realized a problem with this.  Within this theory, sparing 
Lily would make no sense.

Why? - Because how did LV know that Lily wasn't pregnant?

It doesn't seem like he took the time to perform any spell to 
check (if there is such a spell I don't think I'd like to know what
it 
would involve) - he just stormed in and told her to stand aside.  
Since Harry heard his father and mother die within a few 
seconds of each other while under the Dementor's influence, 
and we don't hear LV say anything like a spell, it doesn't seem 
he stopped to check.

Now, I guess it would be possible for LV to count on his spy 
(spies?) to let him know if Lily turned out to be pregnant and go 
back and get that baby!Potter too, but wouldn't this be a pretty 
inefficient way of doing things?  Why not take care of that 
possibility at the same time?  After all, he killing Cedric when it 
was convenient and in his interest without pausing to think 
about.

Was he that sure that Wormtail would know _right away_ if she 
was pregnant?  Would this just be an inappropriate topic for a 
children's book? (pregnancy less appropriate than murder, that 
would be interesting :-) ) 

Or was LV going after James and Harry specifically rather than 
after 'The Potters'?  And if so, why?  Is a new theory in order?

-Ing