Pregnancy tips?

Hi,
I just found out i am 4 weeks pregnancy for the first time ( i am 37). I raced at 2 weeks and at 3 weeks and both weekend I maxed my heart rate. Actually, I had always thought my max heart rate was 185, but it went to 187. I was also not as strong as normal, and my fiance ( we are getting maried in 2 weeks) noticed and wondered if it was becuase i was pregnant. I guess the higher heart rate may also have been due to pregnancy? I am hoping it is a big deal I went to max, since the baby may not have even been attached yet.

My plan right now is to stop racing and intervals, and stay below where my lactic acid even starts to accumulate, probably ten beats below LT or so.

Any recommendations on exercise during pregnancy? I always had the illusion I would swim during pregnancy, do you think it is strange to start?
Any book recommendations for exercise and pregnancy?

I bike to work, but it is along the side of a highway (25 miles each way, though i often just go one way and leave my car, or get a ride). I thought that falling from a bike was big deal last trimester ( placenta can disconnect) so my plan was to ride until then or until i feel uncomfortable. The biggest problem is the doctors are really set up to deal with unatheletic people. So any other information sources would greatly be appreciated.

thank you,
papaya