Respiratory diseases in pregnancy
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Asthma
Prevalence in pregnancy 1-4%
The effect of pregnancy on asthma:
2/5 will deteriorate, 2/5 will stay the same, and 1/5 will improve, women with severe
asthma seem more likely to deteriorate, those showing improvement during pregnancy are
more likely to suffer postpartum relapse.
Management of asthma in pregnancy:
Management of asthma in pregnancy is essentially the same as in non pregnant patients.
Prevention is the key, known triggers of exacerbations should be avoided.
Pharmacological treatment of asthma:
This follows a step by step approach:
Step1 occasional relief bronchodilator (short acting inhaled B2ag.)
Step2 regular inhaled preventative (short acting inhaled B2ag.+inhaled standard dose CS—
corticosteroids)
Step3high dose inhaled corticosteroids ( short acting inhaled B2ag + high dose inhaled
corticosteroids.)
Step4 high dose inhaled corticosteroids+regular bronchodilators.
Step5 regular corticosteroids tablets.
Short and long acting B2 agonists, inhaled steroids and theophyllin can all be used in
pregnancy.
Neonatal apnoea and irritability were reported with theophyllin use during pregnancy, but
this should not inhibit it's use whenever indicated.
Women with more severe asthma who have been stabilized on leukotrienereceptor
antagonists may continue them throughout pregnancy.
It's less likely that pregnant patient will be using antimuscarinic bronchodilators or sodium
cromoglycate, however; no adverse effects have been reported in pregnancy.
Prednisolone is the CS used in pregnancy as 88% of it is metabolized by the placenta, limiting
fetal exposure, however; there's statistically significant 3folds increase in oral clefting with
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steroids use in 1st trimesters, neonatal adrenal suppression has proven to be a theoretical
risk rather than a real practical concern, anxieties about associations with IUGR, neuronal
development, long term hypertension and preterm labour, if real , these complications are
likely to occur in the long term users of high doses. CS are usually only prescribed for good
medical reasons, and usually outside of the teratogenic period.
Managing pregnancy in asthmatic patients:
Standard ANC for mild-moderate cases, multidisciplinary team- based ANC for severe cases
Base line investigations, such as peak flow measurement should be obtained at booking
Medical treatment should be optimized, with repeated reassurance about of these drugs in
pregnancy
Patient with severe asthma should be observed for signs of preterm labour, follow fetal
growth and wellbeing by US
Induction of labour and caeserian section reserved for obstetric indications
Regional anaesthesia is preferred over general anaesthesia for operative procedures
women on prednisolone should be screened for glucose intolerance and measures taken if
this was found, those taking prednisolone at the onset of labour should be given
supplementary doses of 100mg hydrocortisone6-8hourly until oral intake is resumed
ergometrine, prostaglandinsF2α, aspirin, and NSAIDs, should be avoided where possible as
they can cause bronchospasm
postnatal deterioration should be discussed with the woman
breastfeeding is not contraindicated with any of the medications used.
Pneumonia
Prevalence & outcome :
It's no more common in pregnancy than in an age-matched population as a whole, and
maternal outcome is no better or worse, fetal outcome; preterm labour is the main risk,
however; growth restriction have been reported.
Diagnosis of pneumonia in pregnancy:symptoms are same as in non pregnant but may
confused with physiological changes common to pregnancy
Chest X ray – related fetal exposure with appropriate shielding is minimal and the
examination is safe.
Sputum should be sent for microbiological exam and culture
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Blood can be taken for serological testing
Treatment of pneumonia in pregnancy:
Frequently no infectious agent is found and pneumonia treated impirically
Penicillins, macrolides, and cephalosporins are the treatment of choice, non is
contraindicated in pregnancy, higher doses of amoxicillin is needed to counteract the
increased renal clearance found in pregnancy.
Erythromycin and clarithromycin should be added if there is suspicion of atypical pneumonia
Cephalosporins is used for penicillin allergic individuals or hospital acquired infections
Pneumonia requiring admission usually treated with 3rd generation cephlosporine with
erythromycin
Amantadine and ribavirin antiviral agent have been used in pregnancy with viral pneumonia
with no harmful effect.
Tuberculosis:
The relationship between pregnancy & TB
There is no good evidence to suggest that pregnancy is an independent risk factor for
infection with Mycobacterium TB, and it's generally agreed that pregnancy has no impact on
the course of TB and that TB if diagnosed and treated properly has no significant impact on
the pregnancy.
Delayed diagnosis and treatment are both detrimental to both maternal and fetal outcome
With increasing risk of preterm labor and IUGR.
Presentation and diagnosis are unaffected by pregnancy
Vertical transmission is extremely rare and only occur if maternal disease has gone
untreated
Lateral transmission from mother or other close contact occurring after delivery is more
common cause of infant infection
Strict criteria exist for diagnosis of congenital TB,one of the following is necessary
1-lesion in the 1st week of life
2- a primary hepatic complex or caseating granuloma
3-histological evidence of placental or endometrial involvement
4-absence of TB in other carer of the c hild
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Treatment of TB in pregnancy
TB is most likely diagnosed by physician and specialist advice of respiratory consultant is
essential
Isoniazide, rifampicin, and ethambutol are used initially, ethambutol can be stopped when
sensitivity to 1st two drugs is adequate, these are then continued for 9 months.
Most significant toxic side effect of isoniazide is demylination, this can be prevented by
pyredoxin
Hepatoxicity may be more common and this followed by monthly liver function test
No significant in fetal anomaly rate
Liver enzyme induction with theoretical risk of vit. K difficiency should prompt oral vitamin K
supplement in 3rd TMS to prevent haemrrhagic disease of newborn
Ethambutol is associated with fetal ocular toxicity
Pyrizinamide is usually avoided in pregnancy, there are no data to suggest a harmful effect
and should be used if needed as a second line agent.
Streptomycin has well recognized fetal ototoxicity.
All anti TBdrugs mentioned above are compatable with breast feeding
Active TBsufferer will become non-infectious within 2 weeks of commencing treatment, the
newborn should be immunized with BCGand also given prophylactic antibiotics
Placenta should be sent for microbiological exam.
Cystic fibrosis:
Autosomal recessive condition, the life expectancy of affected women is increasing and
many more women are surviving to an age at which pregnancy is possible. It's a
multisystemic disorder principally affecting the lung , liver and pancreas, women are
typically underweight and many develop diabetes,
It's important to check CF carrier status of the husband and the couple should be offered
genetic counseling regarding the risks of the fetus having CF or being a carrier.
Mothers should be jointly managed by obstetrician and respiratory physician expertise in CF
women will have daily physiotherapy regime and will require prolonged antibiotic therapy
and hospital admission during exacerbations.
If delivery is necessary before 34 week, steroid should be given to improve fetal lung
maturation, ideally vaginal delivery should be the aim and epidural analgesia offered, the 2nd
stage can be shortened in the event of maternal exhaustion.
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