I'm a first time mother. Currently 37 weeks and 2 days. Since last night I've been having a lot of pressure on my back. Just now its in my back and going all through my stomach. It feels like a really tightness then it lessens down after a few seconds into an achey feeling again. I'm also very nasuoues with a headache. At my last appointment Tuesday, I was dilated 3cm. Could this be labor?