High CO levels at first pregnancy appointment - should I be worried?

[JenfaK]

I’ve just been for my first appointment for my bloods etc as I am around 8 weeks pregnant. We did the CO breath test and I blew 6 - which is really high. We did a second test as the midwife said sometimes it can be the machine, but the result was 7!
She tested on herself, which came back at a low level and even tested my husband who had a low reading of 2.

I’m stumped about what it could be. We thought maybe my car exhaust (pretty old car) but my husband and I travelled there together in the same car, so that’s unlikely.
We have a carbon monoxide alarm at home so there isn’t a leak there. We live in a new build so it’s unlikely to be a faulty boiler or anything like that. We were both at home all day before the appointment too with the only exception of me travelling to an outdoor fitness class which is a 10 minute drive.

Has anyone else experienced this? Is there something we’ve not thought of that could have caused this?

Do you smoke ?

Nope, never have

Second hand smoke ? Does anyone around you smoke? Definitely get your boiled checked.

passive smoking? sitting near someone who has been smoking? check your CO alarm at home

Did you have your window open when driving? My midwife said fumes from outside can increase the reading and to always drive with windows shut. May be rubbish but that’s what I was told

No I'm not around anyone who smoked at all. Yeah we'll be getting a check booked in first thing. It'd be strange that my husbands levels would be so low if it was down the boiler

I can see that in highly polluted areas but we're quite rural

@JenfaK I can't be of any help but I am in the same boat. I'm 20 weeks now, but I've blown borderline/ high readings (4) at every appointment. Don't smoke/ no second hand smoke, cars all serviced, boiler and stove serviced, new CO monitors at home... even work got their boilers checked again! Like you, I live rurally and traffic not an issue. My husband also was tested and blew 2.
I was referred to the specialist midwife in the end and in fact have been referred for a growth scan at 28 weeks.
There is a link between CO readings and lactose intolerance. I've not tested it out myself but I'm tempted for my next appointment to avoid dairy for a week and see if it makes a difference!

The lactose intolerance thing is interesting. I generally avoid dairy but due to any sort of intolerance. I had a little bit of butter on toast this morning which could account for something but I wonder whether they could create such a high reading of 7!
My husband is telling me not to worry but it's my first so it's hard not to 😅