Don't want to say too much that will identify me, but I am a health professional in this area and like user... feel the need to comment and calm everyone down who seems intent on jumping the gun and concluding that OP must have caught chlamydia from husband in between last pregnancy.
You are not routinely tested for chlamydia in pregnancy. Only under 25s are offered screening.
The blood test indicates previous infection with an infection that most likely is chlamydia. This test looks for markers in your blood's serum - the markers are the same for pneumonia chlamydia. However only the swab will confirm if it is a) genital chlamydia and b) active.
It is possible you had either pneumococcal chlamydia or genital chlamydia many years ago, that has now cleared up.
It is possible you have genital chlamydia that is still there.
Generally, if genital chlamydia is confirmed then depending on the levels of antibodies in your blood test (over 1 in 64 is considered high) you may be offered a laparoscopy (keyhole camera) to see if your tubes have been affected.
Please bear in mind that for a generation chlamydia was incredibly common - hence the free tests, results by text etc. I have looked after literally thousands of women and anecdotally out of those born after about 1985, a good 1 in 4 have had it ... and they're the ones who were diagnosed. It also is not confined to the promiscuous, feckless, particular socio-economic groups etc. I have seen doctors with it.
Please do not worry at this stage. Deal with one thing at a time. Get the swab and results. Then discuss next steps with your partner.
Good luck xxx