A new study from Rotterdam, Netherlands says that kids who share a bed with their parents have a higher rate of childhood asthma.

The study collected yearly questionnaires from over 6,000 mothers while their children were between ages one and six. The questionnaires looked at both the child’s sleeping patterns and any asthma symptoms. It found that children who share a bed with parents during infancy did not have a higher risk of asthma. However, those who shared a bed after the first 24 months did have a higher risk of asthma.

The results could be explained in at least three different ways:

  1. 1. Parents might be sharing their bed with children who wheeze or show other asthma symptoms as a way to monitor their condition throughout the night. However, this reasoning doesn’t explain why there was no correlation between bed sharing in infancy and asthma risk.

    2. It’s possible that bed sharing somehow causes asthma to develop. But it’s unclear why this would be the case.

  2. 3. Parents who share beds with children might just be more likely to notice poor breathing patterns such as wheezing and report them in the questionnaires. They would also be more attentive to any respiratory issues the child develops, and get them to a doctor’s office if need be.

    So it might not be that kids who share beds are more likely to have asthma, just that they’re more likely to be diagnosed with asthma.