The safety issue is that the older child might accidentally hurt the baby. He might try to pick her up when she is crying and drop her. You must deal with this now. Make sure your son knows that he is not to pick up the baby. Also tell him not to put the cat or dog in the crib. Do tell him to call you if his baby sister is upset.

Sleep schedules can be disrupted if the two children interfere with each other's bedtime or if they wake each other up. Perhaps this will not be a problem. If it is, you may be able to deal with it by staggering bedtimes. Also you can teach your children that they have to be quiet when their brother or sister is sleeping.

Children sleeping in the same room might increase the chances that they will catch each other's infections. There is not a lot that you can do about infections spread by coughing. However, if anyone in the family is sick, everyone can try and wash their hands more often as this is a way of reducing spread of infections.

The last concern involves sexual issues. There is no set age when different sex children should not sleep in the same room. You should go by what you and your partner think. Different families will make different decisions.

I believe most people would opt to have separate bedrooms for boys and girls well before they reach puberty, perhaps by six or seven years of age.

There is no evidence that I know of that a boy who is sharing a bedroom with a sister who is about two years younger will cause any problems. If you have any concern that he might be sexually aggressive to his younger sister, then separate them immediately. Similarly, if you find your son or daughter is distressed because their other-sex sibling is in the same bedroom, try to arrange something else.

Sharing a bedroom with a sibling was usual until very recently. It can teach tolerance and problem solving. Sure the kids have less privacy but they have more company.

We now have smaller families and bigger homes. I don't see that kids are necessarily better off because of this.

Patrick J. McGrath OC, PhD, FRSC is a clinical psychologist and a researcher. He is Professor of Psychology, Pediatrics, and Psychiatry at Dalhousie University and Vice President - Research at IWK Health Centre in Halifax. He is also the CEO of the Strongest Families Institute, which provides mental health care to families across Canada.