Demystifying prescribing in pregnancy

Reference: September-October 2025 | Issue 5 | Vol 18 | Page 53

An overview of commonly used medications in pregnancy and breastfeeding, safe prescribing practices, and resources for nurses and midwives

Medication prescribing during pregnancy and breastfeeding can be challenging. The prescriber needs to consider the gestation of the foetus/infant, the known safety of the medication, and the potential benefits and risks to both the mother and foetus/newborn.¹ Many people use their local pharmacist as a resource to guide treatment options.

In pregnancy, many pharmacists will advise the pregnant person to check with their midwife or obstetrician and to obtain a prescription, even for over-the-counter (OTC) medications. Therefore, nurses and midwives require a basic working knowledge of medicines that are considered safe during pregnancy and breastfeeding, as well as their benefits, risks, and contraindications.

Table 1 provides examples of some commonly used medications in pregnancy and breastfeeding.

Medication management in Ireland

In Ireland, medication management is the responsibility of all nurses and midwives. It is guided by the Nursing and Midwifery Board of Ireland (NMBI) within the Code of Professional Conduct and Ethics² and Guidance for Registered Nurses and Midwives on Medication Administration.³

The NMBI also governs the prescriptive authority for nurses and midwives to ensure safe and effective prescribing practices for those on the Registered Nurse Prescriber and Registered Midwife Prescriber registers.⁴

Maternity services in Ireland are governed by the National Women and Infants Health Programme and the Institute of Obstetricians and Gynaecologists of the Royal College of Physicians in Ireland. They are responsible for the various guidelines that guide maternity services care and include medication regimes for various pregnancy complications. These resources are accessible online.

Useful resources

For most practitioners, the British National Formulary (BNF) – which includes a paragraph on pregnancy and breastfeeding – is accessed to guide prescribing practice.¹ If it states ‘not known to be harmful’, it is considered safe, but there is no 100 per cent guarantee for any medication.

If the BNF states ‘manufacturers advise avoid during pregnancy unless the potential benefit outweighs the risk’, then the medication can be considered for use in the absence of an alternative. If this is not a medication that you are familiar with, or is not part of your usual practice, seek further advice prior to its use. If the BNF states ‘avoid’, do not use.

The Health Products Regulatory Authority regulates all medications and devices in Ireland.⁵ Their webpage (www.hpra.ie) is easily accessible and helps guide prescribing practices. Similar resources for breastfeeding include LactMed: Drugs and Lactation Database.

The Rotunda Hospital in Dublin is responsible for the Irish Medicines in Pregnancy Service (www.rotunda.ie/imps/). This service can be accessed by anyone and is a useful resource for all medications, particularly those not used regularly in maternity services. It is also responsible for hosting an annual online ‘Medicines in Pregnancy and Lactation’ study day, which provides up-to-date evidence-based information.

The National Medicines Information Centre based in St James’s Hospital is another useful platform (www.stjames.ie/services/nmic/) with links to a pregnancy-specific prescribing resource.

TABLE 1: Common medications in pregnancy

TABLE 2: Common antibiotics in pregnancy

TABLE 3: Common asthma medications

Managing infections in pregnancy

Treating infections in pregnancy needs some extra considerations. Untreated infections can lead to serious maternal and neonatal complications.⁶ Table 2 provides an overview of some commonly used antibiotics in pregnancy and breastfeeding. Important considerations include:

• Avoid co-amoxiclav, especially in the third trimester (unless no other suitable antibiotic is available), as it can cause necrotising enterocolitis in the term baby.⁵
• Treat any urinary tract infection (UTI), even if asymptomatic, and send a repeat mid-stream specimen a week after completing the course to ensure it has been successfully treated.⁷
• If sending swabs or any specimens to the laboratory always include pregnancy status and gestation, as well as any existing drug allergies, as some bacteria that are considered normal commensals and would not be reported without pregnancy will be reported on; for example, Group B Streptococcus (GBS). This is considered a normal vaginal commensal but its presence during pregnancy needs to be known as it will require prophylaxis antibiotics at the onset of labour if present. It does not need to be treated antenatally unless it is in the urine.⁷

The Drugs and Therapeutics Committees attached to each hospital are also an excellent resource, especially when it comes to antibiotic use. Most have a specific chapter for pregnancy, with treatments based on local knowledge of sensitivities to various bacteria as these differ across the country.

The antimicrobial pharmacist is also available to contact to help decide the best course of treatment for an individual.⁸ They have direct links to the consultant microbiologist if extra decision-making or input is required, as well as a more in-depth report on sensitivities to bacteria not usually reported on the hospital laboratory system, and are a very useful link for informing antibiotic choices if a treatment is not working or keeps recurring.⁸

Managing asthma and allergies in pregnancy

Asthma in pregnancy needs ongoing treatment, and continued use of a usual preventative inhaler should be encouraged as 20-30 per cent of people report poor control/worsening of their asthma in pregnancy.

Women who require their rescue inhaler more than twice a week need re-education about taking their preventative inhaler correctly.⁹ Monitoring the peak flow will often help to reinforce this as they should see an increase in the readings when adhering to treatment. If they are complaining of excess heartburn that is not being relieved by antacid medication, with a decrease in peak flow volume, then consider adding in a daily proton pump inhibitor like omeprazole as heartburn can contribute to worsening asthma in pregnancy.⁹

If these interventions do not result in normal peak flow readings and less than two uses of the preventative inhaler weekly, then refer to the local respiratory nurse specialist services or back to the next antenatal clinic. Table 3 illustrates some common asthma medications and prescribing considerations in pregnancy.

Allergies and hay fever can also worsen in pregnancy. Several OTC medications are considered safe if alternative remedies and treatments have not been effective (Table 4).¹⁰

Vaccination in pregnancy

Other than live vaccines, most immunisations are considered safe in pregnancy, with influenza and covid vaccination being highly recommended to prevent complications secondary to the immunocompromised state during pregnancy cases.^7,9 Pertussis vaccine is also recommended in pregnancy to provide the foetus with a passive immunity to whooping cough.⁷ Women should be advised to avoid a pregnancy for at least three months after the administration of live vaccines.

TABLE 4: Common antihistamines in pregnancy

Conclusion

Nurses and midwives play multiple roles in prescribing medications, supporting and educating patients, and analysing risks and benefits. The resources discussed in this article are the most accessed and used, but it is important to remember your local maternity services. It might be possible to make a call and speak to a midwife or an obstetrician to problem solve at the time, or it may require an earlier appointment at the antenatal clinic or an immediate review. Either way, collaboration is key if any ambiguity about prescribing exists.

TABLE 5: Vaccines in pregnancy