I started doing an hour brisk walk every morning last Thursday. This after a long 3 month break from exercising. My diet hasn't changed just adding exercise to the mix. why did I gain 2 lbs?
This is the reason why I stopped exercising a few months ago, because I gained instead of lost.
should I add those lbs as gained weight or leave my weight at what it is (141) and not count it?

muscle tissue is heavier than fat tissue. You need to check your measurements you could have lost inches.

It takes a lot more time to build up muscle than a week.

There are LOTS of reasons the scale can blip up and down, including changes to exercise routine, which can cause water retention. Or you might have eaten a bit more sodium this weekend, or the walking made you slightly more dehydrated so you're retaining a bit of water. There are literally dozens of little things that can cause scale fluctuations, so I really wouldn't worry about it unless the gain is persistent or continues to go up past 2-3 weeks.

Are you drinking enough water? Your body will retain water when you work out if you aren't drinking enough water everyday. I aim for at least 8 glasses a day and usually end up getting around 10.

Hon, you are pregnant? Week 5??? You know that any lbs fluctuations, especially at week 5, are water retention!!!! You said baby #5 - you got more experience than I do with this ****, I've been everywhere from 120lbs to 130lbs in one WEEK!

You are 141lbs and 5'4, almost 5'5, how come you are trying to lose weight if you are pregnant? I know it sucks for us girls who used to be overweight to see scale gain, but this really isn't the time for it. Just stay active for now.

Totally agree, that if you're pregnant you shouldn't worry about weight gain, stay healthy and fit and you'll be fine....

LOL the reason I worry about it is that I'm trying to stick to when Dr. Sears says on how much weight you should gain. He says you should gain 4 lbs in the first trimester. I'm only on my 5th wk and 2 lbs already.
But this has happened before the pregnancy. Its the reason why I stopped exercising to lose weight on just my diet (18 lbs). I would gain 2 lbs then after I would stop exercising for 2 weeks, it would come off.
I'll try not to worry about it.

I wouldn't take too much stock into what you "should" or shouldn't gain during pregnancy. I mean didn't they say back in the day a woman shouldn't gain more than 20 and now on average women gain 35?

very true