I'm not sure if you mean 5 weeks till your child is born, or 5 weeks till an adopted child arrives?
Reason for asking: The ProRide (we have one) is for infants of a certain weight/height (escapes me now), but basically that can hold themselves upright. You'll start out with it rear-facing and then turn it around later.
The only quibble I have with our proride is that it is quite bulky, but I don't think anyone has made a car seat since 1985 that I wouldn't consider bulky.
I believe the euro-convertible is the one that is not rated for use in the US (though I am sure it is plenty safe), and may not conform to the latest latch/etc requirements? This is what I recall from our time researching the seats - but it has been well over a year.