Well Lornaloo, I seem on the whole to have lost weight with each child, although my tummy was bigger with each pregnancy.
After 5 children - better make that 3 boys really (9,6 and 2)!!! I fail the pencil test and my tummys' never going to be a wash board again . I guess skin can stretch so far and then....
I have exercised throughout all of my pregancies, just altering what I did towards the end and not exercising so much during the 1st trimester when I was chained to the toilet - if you know what I mean!
A good instructor gym or aerobic should tell you what you can/can't do and give you hand-out to back up the info. they supply.
It really is a case of keeping on exercising throughout if your body allows you too, to ensure you keep in shape before/after birth.
Good for you going to the gym. Great it's free - just imagine you're not in the same building you work in!!! Ideally, even if you are staff a gym instructor should be able to work out a programme for you.
A warm up should be about 5-7 minutes - a brisk walk on the treadmill or low level on the cycle) so you just feel warm. Current research says stretches are an option but I like to stretch the major muscles I'm then going to work. As far as your CV, it's good to work within your target heart rate zone. You can look at those pretty charts on the machines, but they're not acurate as they don't distinguish between a 30 year old who's fit and one who's not. There is a formula for getting an accurate reading which means recording your pulse over several days and then doing some maths. If you want that, then let me know!
As a rule of thumb, when you're on each machine, see if during the time you're working hard or not - you should be feeling moderately/quite out of breath (not the warm up). If you're not then go for a higher level (perhaps not the stair climber!!) or longer duration on one machine.
With the x-trainer you should be able to go forward and backwards. Why not try no arms and just balance using the belly button thingy. When going backwards I recommend not using the arm bits and leaving the hands on the rests or just balance!!
It's good to incorporate some weights to increase the size of your muscle fibre (increased metabolic rate) and then STRETCH, STRETCH, STRETCH!!.
Why not also investiate some classes??? hope this helps.