We have not personally encountered this but every one of my friends who have kids noticed a drastic increase in household sickness when the kid(s) went into daycare.

The times I got sick with the most frequency were (1) when I was younger and dating a swim instructor for a children's class and (2) when me and my spouse first started dating I got to find out all the illnesses a Sunday school nursery director gets exposed to. As far as I can tell, children are cute little petri dishes.

Oh yes. Definitely more sickness in the house after kids. Kids don't manufacture diseases, they are just good disease vectors, but the bugs have to come from somewhere. So the big jump in infections happens when they start to be in contact with lots of other kids (preschool, daycare, etc.). And as Emi says, it's all probably exacerbated by the fact that when you start to get a cold without a kid in the house, you just sleep it off. With kid, you HAVE to take care of them, so you notice your misery more and the lack of sleep makes it even more difficult to fight off your own bugs.

I agree that stress and sleep play a big role. We are very lucky in that we have a child that sleeps amazingly well, and are as a result well rested. Some other contributing factors for not getting sick could be:

-we eat very well. Balanced diet with lots of veggies and fruit. As new parents it can be easy to let this one slip

-we exercise daily. I'm by no means an enthusiast, but our daily walk helps to reduce stress, keep open communication between my husband and I, and I believe it contributes to the positive sleeping habits of my child

-We don't freak out over germs. In my opinion, keeping petri dishes in a bubble only makes their immunity suffer, which also makes them better vectors. I've worked in a hospital for over 12 years, and this is my opinion based on lots of observation.

-when one of us starts to feel sick, I put my life on hold a bit. I don't try to get all the grocery shopping done, I cancel those potential social plans, I take a nap while my son does, I don't paint the bathroom :). Just give everyone a good chance to get a bit more rest so that we won't be laid out later.

We have definitely found that we got sick more often once our baby was able to grab for things and put them in his mouth. We go out a lot to cafes and restaurants and our little guy is not shy to lick the highchair or table top before we have a chance to stop him. Then, when we pick him up, he often sticks his fingers in our eyes or mouth and passes the germs along! Our baby is almost 7 months old and my husband and I have already had several colds and the H1N1 flu. The 'best' infection my little one passed along was pink eye. He decided to grab my lower eye lid and two days later I had pink eye!

Fortunately (and somewhat ironically), the baby has not become sick once. He just picks up the germs and passes them to us. I'm also nursing, which helps him fight off any infections he's passes along.

I have not encountered this too much. But, I am at home with my daughter. We go out to lots of places, and she has had a few colds, but I have been able to fight it off. I think it is because I am breast feeding her!??

There's certainly more stress. When my daughter turned 1, I was surprised to discover that I was 20lbs heavier than when she was born, and that certainly could not have been good for my health (I've since put forth some effort to lose most of that weight).

I have been sick more often since becoming a mother, but I chalk it up to sleep deprivation and too much stress taking a toll on my immune system. Plus, breastfeeding, I feel like baby sucks all the energy/nutrients/etc. out of me. haha. She's healthier than I am, that's for sure.

The constant picking up every virus that's going around tends to slow down a bit around grade 3 when they've all been nagged enough about using a tissue not their shirts to wipe their noses and are more consistent with washing their hands. Then it strangely seems to pick up again in High School. I think my teenagers arn't getting enough sleep, so they're catching everything that they come in contact with.