Asthma
is one of the most common medical problem that can seriously
complicate pregnancy. Approximately 3-5 percent of all
pregnant women have asthma and 20 percent have some type of
allergic disorder. Except in most severe cases, asthma is no
bar to normal delivery and caesarean section is no more common
than in non asthmatic population.
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How
asthma affects mother and foetus
during pregnancy ?
Uncontrolled
asthma can have an adverse effect both on mother and foetus.
When asthma is severe less oxygen will reach to the lungs.
Even from this deficient supply mother sacrifices some share
of oxygen for foetus. On one hand supply of oxygen is reduced
while on other hand it is shared between mother and foetus.
Mother tries to save the foetus at the cost of her suffering
and suffers from complications of deficient
oxygen.
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These complications include hyperemesis
gravidorum,
vaginal haemorrage, toxemia and complicated labor. Despite of
suffering when mother can not maintain foetal oxygen supply
adequately foetus also suffers. Foetal complications include
premature birth, low birth weight, neonatal hypoxia and foetal
death. Sometimes when asthma is severe enough it may even cause death
of the mother. Death is usually from mucous impaction causing
asphyxiation or from tension pneumothorax.
In view of these potential problems asthmatic mothers should
realise that they are breathing for two persons. Therefore for
the sake of two lives asthma must remain under control during pregnancy.
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Who will get severe asthma
during pregnancy?
Generally
it appears that in equal number of patients asthma improves,
worsens or stays the same during pregnancy. However, the
course of the asthma is often consistent in an individual
woman's successive pregnancies.
Women with more severe asthma prior to pregnancy are more
likely to experience severe asthma during pregnancy The peak
incidence of flares during pregnancy appears to be between 24th
and 30th
week of gestation, particularly in women whose asthma worsen
with pregnancy.
Fewer symptoms are experienced by all pregnant asthmatic woman
during weeks 37-40.
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Patients with mild to moderate asthma
are likely to improve throughout the pregnancy, particularly
during last trimester but in one third that improvement may be
followed by postpartum deterioration.
These changes are attributable to the effects of pregnancy
rather than natural course of asthma because most women revert
to their pre pregnancy status with in one to three months of
postpartum period.
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Which
asthma therapy is safe in pregnancy?
On one
hand uncontrolled asthma is dangerous and on the other hand some
asthma medicines are not safe for foetus. Therefore therapy of
asthma during pregnancy requires more care and attention.
Following may be helpful in this regard,
- The oral
sympathomimetic drugs have some complications therefore
inhaled forms are preferred. Inhaled forms of
sympathomimetics are not absorbed. Therefore considered
safe both during pregnancy and lactation.
- Sodium
cromoglycate is also a safe drug both during pregnancy
and lactation.
- Oral
forms of steroids have been shown to cause some adverse
effects. Inhaled forms such as Beclomethasone are
considered quite safe. Budesonide is not indicated
during lactation.
- Theophylline
during pregnancy is as safe as in a non pregnant woman.
During lactation less than 1% dose goes to milk. Rarely
this dose can cause irritability and insomnia in new
borns.
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What
an asthmatic woman do when she detects pregnancy?
Self
management,
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Observe
for symptoms: cough, chest tightness, nocturnal
awakening, wheeze.
- Peak
flow record provide reassurance both to patient and
doctor. Consult a doctor when it falls.
- Should
know which medicines are safe.
- Should
know what
to do on getting cold or throat infection.
- Should
know what
to do on exposure to a trigger factor.
- Take
a written action plan of various situation from your
doctor and clearly understand importance of follow up
visits.
There
is a strong genetic predisposition therefore asthmatic
mothers should adopt measures of primary prevention.
- Breast
feeding.
- Avoidance
of tobacco smoke during pregnancy and lactation.
- Control
of home environment to reduce allergen exposure.
- Delayed
or avoidance of potential dietary triggers.
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| Management
of acute asthma during pregnancy |
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Approximately
10-15 percent of pregnant asthmatic women require hospitalization for treatment of status asthmaticus. The
condition has been associated with maternal and foetal
deaths as well as intra-uterine growth retardation.
Foetal jeopardy exist when maternal arterial pO2 drops
below 60mm Hg. |
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Labor
and Delivery
The
majority of well managed asthma patients do not show any
symptoms of asthma during labor and they may require at
the most inhaled beta 2-agonists. Steroids dependent
asthmatic patients may need extra dose of steroids for
stress of labor. A current protocol is as follows,
- Continue
oral Theophylline/inhaled sodium cromoglycate/inhaled
Beclomethasone/ inhaled beta 2-agonists of antepartum
regimen.
- For
asthma symptoms during labor: Inhaled Terbutaline/Metoproterenol/Salbutamol,
1-2 puff or nebulization hourly or as needed.
- If
above is not adequate: Intravenous Methylprednisolone.
- In steroids dependent asthmatic patients: 100 mg
Hydrocortisone intravenously and may be repeated every 8
hour interval.
- If
anesthesia is required, local anesthesia is preferred
with spinal anesthesia for caesarean section. If
general anesthesia is required nitrous oxide and
halothane are preferred. Cyclopropane should be avoided
since it may cause broncho-constriction.
Breast
Feeding
Medications used in asthma rarely
cause problem for infants and therefore breast feeding should
be continued. Infants of mother receiving theophylline
receives less than 1 percent of the drug but in some it may
cause irritability and insomnia. Inhaled beta 2-agonist are safe
and appear in negligible amount in breast milk. Less than 20
percent of daily physiological requirement would be received
by an infant of a mother receiving 50 mg Prednisolone daily.
To ensure the lowest drug concentration in the milk, nursing
mothers can take any necessary medication 15 minutes after
nursing.
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