I've read that you should put off whatever you can during the first trimester. If you've got serious decay, then obviously you need to deal with that, but a routine cleaning could be delayed until the second trimester.
As for the whitening, why can't that wait until after you have had the baby and they are a bit bigger? If you do it now you will pass on whatever goes into your body directly to them. Why expose the baby to stuff when you don't need to? It would be a lot less harmful to your child to get your teeth whitened when they are 3 months old for example than to do it now when they are still growing so much and forming their organs.
Routine cleanings are safe at any time as far as what I've been told by my dentist and my midwife. Gum disease can actually cause complications like preterm labor, so best to keep an eye on overall oral health. I've had two routine cleanings during this pregnancy, one at 5w, one at 7 months, and I made sure to inform the staff I was pregnant, which meant they knew not to offer me x-rays.
I would not do whitening, however. Cleaning is a mechanical process with scraping and polishing, but whitening introduces chemicals, so why risk it.
If your cleaning showed something that needed to be addressed, then you can discuss the risks and benefits of that additional procedure with your care provider and dentist.
As a former hygienist ( and mom) Cleanings are safe and if you have increased gingivitis during your pregnancy - as many women do it is actually advised to go every 3 - 4 months. Periodontal disease has been linked to premature labor so take care of your gums. Alot of women put off dental work ( fillings & crowns) until the 2nd or 3rd trimesters.
Bleaching your teeth is NOT remommended. I believe the package insert in the bleaching kit says to avoid if pregnant ( you can ask to see one)
My dentist didn't want to do anything on my while pregnant. Not even a cleaning. I had a cleaning done about 2 weeks before I got pregnant. Now their office says to wait until the baby is born to do the fillings. They even said they don't like to clean while pg....even though I have heard all the things the pp's mentioned about gum disease. I think it may have something to do w/ my heart. I have mitral valve prolapse and have to take pre-dental antibiotics. My dentist says that any cleaning poses the risk of infection being introduced into the bloodstream because the gums usually bleed a bit. Weird.