Sure, they wouldn't have been able to do anything, but as you say, it would have served to give them all a heads up earlier, which could have had bearing on certain decisions/influence them to be more careful. If not that, then at least it would let the team be destroyed in a more believable manner for the sake of the quality of the plot (ie, they did all they logically could under the circumstances, but they couldn't stop themselves from being killed).
Probably suffering from shock (don't forget that c-section)
Thats one other thing I found funny - she just had a freaking caesarean
.. she shouldn't be able to stand
after that, let alone run. Also, a lot of the alien's fluids spilled into her open wound..
But that's not really a big problem, as her rate of recovery can easily be attributed to the medical science of 'the future' (Magic staples, maybe? Or maybe the things she was stabbing herself had some sort of healing factor accelerator, along with painkillers..).
Just interesting to think about.