What can I do to lower the humidity in my bathroom?

A good exhaust fan or dehumidifier is about the only answer. Make sure there is a gap between door and the floor (1 inch) for the fan to pull air through. If you have to leave the fan running unfortunately that's the price you pay for having a kid. If you don't get the humidity down you're going to start having mold problems which you already say you can smell. Mold can be a serious health risk not only to you but your child.

A good idea is to get a dehumidifier (however beware they can get pricey) and set it to run in the bathroom. We recently got on for our basement and it's pretty good. It's from Whirlpool and it has an auto function, as well as settings like normal, dry and extra dry. Also mop up the puddles on the floor.

Maybe get a little pen for the baby and put him in there and let the door open.

You should keep the door open at night and when the baby is napping. Also, get a couple of boxes of baking soda from the store and put them in discret locations throughout the bathroom. Baking soda will absorb the mildew odor and some of the dampness.

All you need to do is get a good exhaust fan.I had the same problem,and when I connected the fan,bingo problem solved.The fan has to be able to shoot the steam to the outside of the house,or room.Believe me you see a 99% difference,of course if you take really hot steamy showers it might cut down that percentage considerably.

do not use an air conditioner,,you will just have cold humidity!! that is what exhaust fans are for,, if you don't have one see about having one put in,, on a wall it can vent straight out,, in the ceiling you have to go up and then run a conduit out the wall from the attic..

sounds like the toilet emits that smell - my old house was like that. Unfortunately, your options are leave the door open or run the fan. But with the little on, you could try some of those Glad pulg-ins or some of those old renuzuit smelly-gelly things like grandmum used to use. They actually work.

well other than installing a ceiling exhaust fan, try opening the bathroom window,to allow the steam to flow out.

Make a point of always opening your windows after you bath or shower to let the steam out - you can use kitty litter to absorb humidity too - you will of course need to put it well out of reach of your toddler - or stitch it into a cotton bag.

Use AC, desert Cooler fitted from outside or an exhaust fan

I would install an exhaust fan in the bath room ceiling and run it when bathing or showering.