Pregnancy is a time of intense change within the female body.
Hormonal changes have an influence on the immune system and allergic diseases
may be affected by these changes. The hormones of pregnancy have
steroidal type effects and can also dampen down allergies. In the
pregnant state, the immune system is down-regulated to prevent rejection
of the foetus (which is immunologically a "foreign organism").
This increased immune tolerance has the positive spin-off of causing less
direct reactivity to foreign substances. However, the allergy triggering
potential of the immune system may be heightened.
What happens to existing allergies in pregnancy
Asthma for example may become worse with frequent attacks, it may even
occur for the first time in pregnancy. But paradoxically it may become
less severe and easier to control during pregnancy. Good Asthma control
is important in pregnancy to maintain an adequate oxygen supply to growing
foetus. Prematurity and low birth weight may result from poor asthma control in
the mother. Most asthma drugs can be safely used in pregnancy and there is no
evidence that there is any increased risk to the foetus. We do however
recommend the lowest possible doses of any medication sufficient to control
symptoms in the pregnant mother.
Nasal allergies often occur for the first time in pregnancy.
Pregnant mothers are prone to nasal blockage and irritating nasal symptoms and
increased nasal discharge. This state of affairs seems to be triggered by the
hormones present in pregnancy.
Urticaria and allergy-like rashes are also common in pregnancy.
One particular rash that is perculiar to pregnancy is the Pruritis and
Urticaria Papules and Plaques in Pregnancy ( PUPPP syndrome). This
manifests with intensely itchy eruptions, particularly on the lower abdomen and
upper thighs of the pregnant person. After the birth, the rash rapidly
disappears but is most debilitating during the last few months of pregnancy.
Eczema on the other hand often improves in pregnancy and this may
possibly be due to the increase in the body's natural
cortisone-like steroids that occur in pregnancy.
Preventing allergies in the unborn
As far as the unborn baby’s health is concerned, the pregnancy and treatment
thereof can have profound impact on the foetus’s health and predisposition to
allergy. We know that if the mother has allergies there is a 30% chance
of her baby having an allergy. If both parents have allergy, the baby’s
risk increases to 60% and if both parents have the same allergy for example
asthma, then the risk of allergy in the unborn baby reaches 80%. Maternal
smoking during pregnancy and the eating of allergy provoking foods in her diet
in the last few months of pregnancy may encourage allergic diseases to develop
in the baby. The evidence is still not convincing that diet in early pregnancy
makes any difference.
We know that unborn babies start to produce the allergy regulating
IgE antibody from 20 weeks of gestation. We used to measure Total Cord
Blood IgE levels at birth as an indicator of possible allergy development, but
this test is not very accurate, so is no longer used.
Smoking in early pregnancy is potent trigger for the development of
allergies in the unborn baby and if the baby is born into a smoking household
this risk increases. The month of birth is extremely important. If a baby
is born to allergic parents and the birth month coincides with the beginning of
the pollen season, then there is an increased risk of nasal allergies and
asthma.
Reducing
the risk of allergies in infancy
Plan Breast feeding carefully! The
best scenario is exclusive breast feeding with no top-up formula feeds and a
mother who pays special attention to her own diet. No half measures can
tolerated! Although Breast-feeding is the recommended form of
infant feeding as it provides the best nutrients and immune protection, we must
warn breast-feeding mothers to strictly avoid all allergy provoking foods in
their own diet. Traces of these allergy provoking foods can be found in
the mother’s breast milk shortly after eating them and this could possibly lead
to allergic sensitisation in the baby. Also be careful not to use nipple
creams that contain peanut (Arachis) or nut oil extracts, as these may also
lead to nut sensitisation in the baby.
Paradoxically, a home environment that is meticulously sterile and
contains no animals at all might actually promote allergy development in the
newborn. This is the basis of the “Hygiene Hypothesis”. The “dirtier”
the infants initial environment, the less likely that allergies will
develop! We find that babies born into large families, with early
exposure to usual childhood viruses and those born on livestock farms are less
likely to develop allergies. Those born into families with only a few
siblings and no exposure to dirt or animals or exposed to antibiotics early in
life are more prone to develop allergies. Early exposure to day care
environments at a few weeks of age, may also reduce allergies. There is
no evidence that childhood immunisations promote allergy development.
Natural bowel germs called Lactobacilli (found in Natural Yoghurt) may have a
protective effect.
Special attention should be given to protecting the newborn from
allergens, we recommend using liberal emollients such as Aqueous cream on the
skin, avoiding perfumed soaps and all biological detergents. Cotton
clothing and mittens are preferable to synthetic and woollen clothes. Bath
additives and bubble baths should be avoided only use products such as Oilatum
in the bath. Carefully read labels and avoid Vitamin and medications with
colours added. Even herbal or Homeopathic medications should be viewed with
suspicion, as these are possible sensitising agents.
Do’s and Don’ts of Pregnancy in Allergy prone mothers
Pregnant mothers should:
- Not smoke cigarettes and avoid passive smoking.
- Avoid excessive alcohol
- Avoid allergy provoking foods such as peanuts, nuts, sesame, eggs and fish.
- Avoid excessive exposure to pets such as cats, dogs, horses and house-dust.
- Continue to take regular prescribed Preventer and Reliever Asthma medication throughout pregnancy. The Reliever Beta Agonists actually help to relax the uterine muscles. Medication such as aspirin, beta blocker medication and codeine are other possible allergy triggers.
- Avoid all non-prescription drugs and vitamins that contain colourings or additives.
- We recommend avoiding any allergy provocative procedures in pregnancy such as Skin Scratch Testing or Desensitisation Immunotherapy.
- Pregnant women should continue to exercise, eat a balanced diet and get plenty of sleep.
Newborn babies should have:
- Exclusive breast feeding for 6 months if possible
- Avoid exposure to cow’s milk and formula milk unless hypo-allergenic formulas
- Be exposed to normal childhood viruses
- Avoid antibiotic treatment for viral illnesses unless essential
- Avoid creams containing nut oils, perfume and additives
- Avoid all processed baby foods and rather eat freshly prepared foods from the age of 6 months.
- Avoid all exposure to cigarette smoke.
- Immunisations should be given as usual.
Dr Adrian Morris
November 2003
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