I had Lyme when I was pg...but didn't know it. Nursed all kids for at least a year, youngest for almost 2...Had been infected for the first time many years earlier. All 3 of my kids had positive markers for Lyme, though the only one who has actually tested positive is my oldest and he was bitten and had a bullseye rash(treated for a month but wasn't enough as he already probably had Lyme from me) Now we are treating him again as he has many of the same symptoms as I do.
Studies say Lyme can be passed congenitally and through breatsmilk. I believe it.
So far my other 2 have no symptoms. My daughter was born with a congenital heart defect...no history in our family though. I had a hard time carrying my kids to term...all 3 were early, my daughter was 5wks early, my youngest was trying to come out at 30 weeks(kept him in to just shy of 37 with meds) Is all that from Lyme? Maybe...hard to say. I think you are right to investigate for your child though...and any future children. Apparently, going on abx while pg. greatly reduces the incidence of spreading the Lyme to your baby.