Asthma in Pregnancy
...Your Questions Answered

Asthma is a chronic inflammatory disorder of the airways. The chronic inflammation is associated with airway hyper-responsiveness that leads to recurrent episodes of wheezing, breathlessness, chest tightness and coughing (particularly at night or in early morning).

Asthma is the most common, potentially serious medical problem to complicate pregnancy. It is estimated that asthma currently affects 3.7% to 8.4% of pregnant women worldwide.

The pregnant patient may develop asthma for the first time during pregnancy. In contrast, in other pregnant patients with pre-existing asthma, the asthma may worsen In a third of women. Improve In another third, or remain unchanged in the remaining third during pregnancy. It is, thus, difficult to predict specifically as to how a patient's asthma may be affected during pregnancy.

Outcomes of pregnancy in asthmatic women have suggested that uncontrolled asthma can have adverse effects on both the mother and foetus which may lead to- increased risk of perinatal mortality, higher rates of pregnancy induced hypertension or pre-eclampsia and caesarean section, vaginal haemorrhage, preterm births and low birth weight infants, neonatal hypoglycaemia and seizures, premature rupture of membranes, transient tachypnea of the new born. Patients with more severe asthma are at a greater risk. If asthma is controlled, these adverse outcomes can be avoided. Thus, pregnant asthmatics should be closely monitored by way of pulmonary function testing during pregnancy.

Diagnosis of asthma can lead to a healthier and less risky pregnancy, by decreasing the adverse effects of breathlessness on the developing foetus.

The diagnosis of asthma is based on:

A clinical diagnosis of asthma is often prompted by symptoms such as episodic breathlessness, wheezing, cough and chest tightness. Episodic symptoms after an incidental allergen exposure, seasonal variability of symptoms and a positive family history of asthma or atopic disease are also helpful diagnostic guides.

A good history and clinical examination usually suffice to diagnose asthma in most patients.

Pulmonary function tests like measurement of peak expiratory flow rate (PEFR) with the help of a simple tool called peak flow meter can also aid in the diagnosis of asthma. PEFR is the easiest and most commonly performed test. It is the fastest rale at which air can move through the airways during a forced expiration starting with fully inflated lungs.

The peak flow varies according to age, sex and height. An asthmatic's normal peak flow should be within 20% of that of a person who is of the same age, height and sex, but who does not have asthma.

The ultimate goal of asthma therapy in a pregnant woman is to achieve optimal asthma control for Improved maternal and perinatal outcomes. This is expected to be met by preventing hypoxic episodes and preserving continuous foetal oxygenation. Thus, effective asthma management revolves around these four basic components of asthma therapy:

The stepwise approach to therapy, which remains similar to the asthma management in the adults, in which the dosage, number of medications and the frequency of administration are increased as necessary and decreased when possible, is used to achieve and maintain asthma control.

Many pregnant women and their doctors are concerned about the potential effects of the asthma drugs on their babies as well as on the women themselves. It is, however, safer to take asthma drugs during pregnancy than to leave the asthma uncontrolled.

Treatment of the pregnant asthmatics should include medications required for acute symptoms (relievers) and chronic treatment (controllers) as reviewed in the table below:

Relievers and controllers can be administered through oral, inhaled and parenteral routes.

However inhalation therapy is the most preferred route of administration and world over most asthmatics are treated with inhaled drugs. Inhaled drug delivery puts the drug where it is needed, whereas oral tablets and syrups must be absorbed in the gastrointestinal tract and need to travel through the bloodstream to various parts of the body before they reach the lungs.

A wide range of inhaler devices are available today which has made inhalation therapy more convenient and accessible.

Most asthmatics though asymptomatic have abnormal airways due to underlying inflammation. Without adequate controller therapy, these patients frequently develop symptoms. Thus, they shuttle between asymptomatic and symptomatic state. Adequate controller therapy can restore the airways near to normalcy.

Corticosteroids are the most effective treatment for airway inflammation of asthma and reduce the hyper-responsiveness of the airways, which decreases the incidence of exacerbations by more than threefold in users, compared with those who do not use inhaled corticosteroids. A concern about the risks of congenital malformations with inhaled corticosteroid exposure in the first trimester has proved unfounded; multiple studies have confirmed their safety regardless of dose. In fact. It has been proven that patients with inadequate inhaled anti-inflammatory treatment during pregnancy are at a higher risk of an acute attack of asthma.

Asthma exacerbations have the potential to lead to severe problems for the foetus. Exacerbations are most likely to occur between 24 and 36 weeks of pregnancy. Therefore, asthma exacerbations during pregnancy should be managed aggressively. A decrease in foetal movement may be an early manifestation of an asthma exacerbation. Hence, the most important part of managing such an event is the prevention of exacerbations.

If the patient experiences dyspnoea due to asthma, successive treatments with a beta₂-agonist such as salbutamol should be administered via a pressurized metered dose inhaler (pMDI) or nebulizer. Most of the studies and data available are on salbutamol, whose safety and efficacy is well-established. Evidence to date in animals and humans suggests that beta-sympathomimetics do not increase the risk of congenital abnormalities.

Given below are the steps for the management of an exacerbation presenting in the emergency room:

If multiple doses of inhaled beta₂-agonists are required or if peak flow and/or FEV₁ remain <70% of personal best/predicted: