Same as most PPs I'd be talking about it but ultimately being OK with him going if that's what he wanted.
If no real health probs for you, maybe like Mak suggested get someone to come and stay with you while he's gone?

I live by myself with the kids. My DH works on a remote community 250kms away far from the tar. It took some adjusting but I'm pretty proud of myself for being so OK. We have no family for support either, but we have been able to set up a few contingency plans just in case. Most people are happy to help if they're asked. I have silly stuff like a note on the fridge with contact details of people here in town, DH, the police station (to contact DH via radio if I can't), his boss, my mum (so dad can put her on a plane straight away) etc just in case I have to call an ambulance or someone in a hurry. A couple of GFs know where my bag is and I've left a note in the top of the few things that are left to go in there.
The hospital know both about my very high risk preg (of course) but also of DH and my situation. I'm lucky enough to have a 5.5yo who's been around 000 operators for a long time so is confident to dial 000 and give her details should need be. I know your little guy is too little for that but what about a printed medical history and someone to call every few hours to make sure you're OK if no-one can stay with you?