Asthma is considered to be one of the commonest medical problems faced by a pregnant woman (1).
The effect of pregnancy on asthma is variable. Around a third of patients improve, a third worsen and a third continue unchanged (2)
- a prospective cohort study of 1,739 pregnant women, an overall improvement in asthma in 23% and deterioration in 30.3% during pregnancy was seen
- a systematic review concluded that, if symptoms do worsen, this is most likely to occur in the second and third trimesters, with the peak in the sixth month
- there is also some evidence that the course of asthma is similar in successive pregnancies (3)
Increased progesterone and levels of free cortisol associated with pregnancy have bronchodilatory effects. This is countered by the reduced residual volume and increased PGF2 alpha secretion which promote bronchoconstrictor effects.
On the other hand uncontrolled asthma may cause several maternal complications (hyperemesis, hypertension, pre eclampsia) and fetal complications (fetal growth restrictions, pre term birth and neonatal hypoxia). There is no evidence of an increased risk of an asthmatic attack during labour.
Clinicians should offer pre-pregnancy counselling to women with asthma regarding the importance and safety of continuing their asthma medications during pregnancy since well controlled asthma throughout pregnancy has little or no increased risk of adverse maternal or fetal complications.
- monitor pregnant women with moderate/severe asthma closely to keep their asthma well controlled.
- advise women who smoke about the dangers for themselves and their babies and give appropriate support to stop smoking
- women with asthma should be advised of the importance of good control of their asthma during pregnancy to avoid problems for both mother and baby (3)
NICE state with respect to asthma in pregnancy (4):
- people with asthma should have an asthma review during early pregnancy and in the postpartum period. Emphasise the importance and safety of maintaining good control of asthma during pregnancy and of continuing asthma medicines to avoid problems for themselves and their baby
- advise anyone who is pregnant and who smokes about the dangers for themselves and their babies and give appropriate support to stop smoking
- advise using the following medicines as normal during pregnancy:
- short-acting and long-acting beta2 agonists
- inhaled corticosteroids
- oral theophyllines
- oral corticosteroids during pregnancy should be offered if needed to treat exacerbations of asthma
- advise that the benefits of treatment with oral corticosteroids outweigh the risks
- if leukotriene receptor antagonists or long-acting muscarinic receptor antagonists are needed to achieve asthma control, they should not be stopped during pregnancy
Asthma in pregnancy (4):
Analgesia for women with asthma
- offer women with asthma the same options for pain relief during labour as women without asthma, including:
- Entonox (50% nitrous oxide plus 50% oxygen)
- intravenous and intramuscular opioids
- epidural
- combined spinal–epidural analgesia
Prostaglandins for women with asthma
- do not offer prostaglandin F2 alpha (carboprost) to women with asthma because of the risk of bronchospasm
- consider prostaglandin E1 or prostaglandin E2 as options for inducing labour in women with asthma because there is no evidence that they worsen asthma
- consider prostaglandin E1 as an option for treating postpartum haemorrhage in women with asthma because there is no evidence it worsens asthma.
Drug therapy in breastfeeding mothers
- use medicines as normal when breastfeeding in line with recommendations in the BNF
Notes:
- advise women:
- that acute asthma is rare in labour
- to continue their usual asthma medications in labour
- women receiving steroid tablets at a dose exceeding prednisolone 7.5 mg per day for > 2 weeks prior to delivery should receive parenteral hydrocortisone 100 mg 6-8 hourly during labour
- in the absence of acute severe asthma, reserve caesarean section for the usual obstetric indications (5)
Reference: