What are some of the main factors involved?

Having a family history of asthma or allergies increases the risk of a baby developing these conditions. Smoking during pregnancy, and exposure to secondhand smoke during infancy and childhood also increase the risk of the infant developing asthma and respiratory problems.

Prevention is best

About one in three New Zealanders will be affected by allergies some time during their life. Allergic diseases have increased in Western countries, and their frequency has approximately doubled over the last 25 years. Although effective treatments are available, there are currently no cures for allergies or asthma. Therefore, it makes sense to try to prevent allergies, if possible, in infants and children - not smoking during pregnancy or around infants and children is a preventive measure you can take.

Family history and environment play a part

Both genetic and environmental factors are important in determining whether someone will develop an allergic (atopic) condition such as asthma, rhinitis (hay fever) or eczema. Babies are at high risk of developing allergies if there is a family history of allergies or asthma. The chance is increased if both parents are affected.

What can I do during pregnancy to reduce the chance of my baby having asthma?

• Don't smoke: The most important advice for a pregnant woman is not to smoke. Smoking during pregnancy increases the risk of your baby developing asthma, bronchitis and wheezing illness. Exposure to second-hand tobacco smoke after birth also increases the risk of poor respiratory health. It is unclear whether smoking during pregnancy affects the risk of allergies. (For help in giving up smoking, see Quitting)
• Diet: There is no evidence that you can reduce the risk of your baby having asthma by altering your diet when pregnant or breastfeeding. However, if you have food allergies yourself, continue to avoid these foods for your own health. It is important to let your doctor or midwife know so they can check that you are still getting the right nutrition for you and your baby. Also see: Eating well in pregnancy
• Allergen avoidance/exposure: Early exposure to some things that cause an allergic reaction (allergens) may be significant in the later development of asthma and may be protective against developing asthma and other allergic conditions. New Zealand research has shown that babies who were born in a farming environment and therefore exposed prenatally (before birth) to farm animals were protected against childhood asthma, hayfever and eczema. Children exposed to cats and dogs, and those from larger families also appear to have a lower risk of allergies. Further important research is being undertaken in New Zealand to look at this issue further.

What can I do to prevent my infant developing asthma?

• Breastfeeding: Breastfeeding has formerly been thought to be protective against the development of asthma and allergies, but recent studies have cast doubt on this. There are still many good reasons to breastfeed your baby, but to protect against developing asthma and allergies may not be one of them. Further research is currently being undertaken in this area.
• Avoid smoking: Do not smoke around your baby or in enclosed spaces where children will sleep and play. Exposure to tobacco smoke increases the risk of children developing asthma or suffering sudden infant death syndrome (SIDS). It is also linked with increased frequency and severity of asthma symptoms in older children with asthma.
• Allergen avoidance: There is little evidence that avoiding allergens will have any long term impact on your child's risk of developing allergies. In fact, the evidence suggests that exposure to cats and dogs and farm animals may reduce a child's risk of allergic disease. More study is needed in this area, however.
• If allergies have developed: Of course, if your child has already developed allergies, the situation is different. Avoiding or minimising exposure to the allergens your child is sensitive to, may help to reduce their symptoms.

How important is diet in the development of asthma and other allergic conditions?

Most babies with wheezing do not have allergic triggers. Irritants such as colds (viruses) and cigarette smoke are much more common triggers. However, if there is a very clear family history of food allergy it might be worthwhile removing these food items from the baby's diet, or if the baby has problems with eczema or starts to wheeze when given a new food.

To avoid the risk of your baby not receiving a balanced diet, always talk with your doctor or a qualified dietitian before excluding any foods from your baby's diet.

Related topics

Also see: Asthma in infancy and childhood

Original material provided by the Asthma Foundation of New Zealand, 2010, Edited by everybody, December 2010.