There are some reports of allergies developing after pregnancies, sometimes subsiding after "some time", sometimes not. I haven't really found anything concrete, though.
You could try asking Chris Kresser or Paul Jaminet. I think Chris typically charges a consultation, but you may be able to get away with a quick freebie, with the more detailed follow-up being what costs you. Paul is more than happy to answer any questions that are sent his way. Both follow the research very closely and if the answer is out there I'm confident one of them will have it.