Medicines used in pregnancy
On this page you will find information and resources on prescribing in pregnancy
Medicines in Pregnancy, Children and Lactation
Information on the use of medicines in human pregnancy is generally lacking, especially for new or infrequently used products.
Bumps is provided by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by Public Health England on behalf of the UK Health Departments. UKTIS answers enquiries from health professionals (e.g. doctors, nurses, midwives) on the effects on the unborn baby of medicines and other chemicals that the mother may use or otherwise be exposed to.
Somerset NHS Foundation Trust have commissioned printable leaflets. Choice and Medication© leaflets are designed to help service users, carers and family members understand their medicines better, and to make more informed decisions, best as part of a discussion with a healthcare professional.
Please see the Traffic Light System included in netFormulary entries for categorisation of individual drugs which defines where responsibility for prescribing between primary and specialist clinicians should lie.
Pregnancy Planning & Staying Well in Pregnancy & Beyond
For more information on planning pregnancy, staying well in pregnancy and beyond, please see the Medicines in pregnancy, children and lactation - NHS Somerset ICB page where we also discuss the safety of medicines taken by either parent and access links to book in with maternity when a positive test happens.
Please expand the topics below for more detailed information.
Resources
UK Teratology Information Service (UKTIS) provides various maternal exposure abstracts openly available as well as paternal exposure abstracts. Healthcare professionals can contact the service Monday to Friday.
Best Use of Medicines in Pregnancy (Bumps) is provided by the UKTIS, various patient information leaflets are available suitable for the public, useful for all.
Specialist Pharmacy Service SPS has published significant resources on many areas of prescribing in pregnancy, including the prescribing in pregnancy and safety in pregnancy- training and treatment resources in pregnancy
For comprehensive advice and training materials Safety in Pregnancy – Specialist Pharmacy Service (SPS) has resources on:
Questions to ask when giving advice on medicines in pregnancy
Information resources that give advice about medicines in pregnancy
Assessing risk and informing the risk versus benefit decision for medicines in pregnancy
The principles of prescribing in pregnancy NOTE: Full update July 2025
Royal College of Gynaecologists (RCOG) Green-top Guideline No.69 The Management of Nausea and Vomiting of Pregnancy and Hyperemesis Gravidarum. Also see formulary guidance below under Nausea and Vomiting.
Electronic Medicines Compendium (EMC) – Individual drug data sheets, contain information published by manufacturers.
Somerset NHS Foundation Trust have commissioned – Choice and Medication© leaflets which are designed to help service users, carers and family members understand their medicines better, and to make more informed decisions, best as part of a discussion with a healthcare professional.
Antiepileptic drugs in pregnancy: updated advice following comprehensive safety review MHRA January 2021 update.
The NHS website has some useful information on becoming a parent and discusses testosterone and fertility.
People assigned female at birth (AFAB) can become pregnant while taking testosterone if they do not use contraception.
Somerset’s Fertility Policy can be accessed through the Evidence Based Interventions Service page, under policies and applications.
Public Health and Prevention
Folic acid should be taken by all women and people assigned female at birth who may become pregnant to reduce the risk of having a baby with a neural tube defect. This advice remains regardless of local food fortification mandates. UK Chief Medical Offcers Chief Nursing Officers and Chief Midwifery Officers - Folic Acid Supplementation.pdf
Usually folic acid 400 micrograms daily should be started 3 months before pregnancy (where possible) and continued throughout the first 12 weeks of pregnancy, this is available over the counter and suitable for self-care.
NICE Public Health Guideline [PH11] advise that GPs should prescribe 5mg of folic acid a day for women and people assigned female at birth who are planning a pregnancy (3 months before conception where possible), or are in the early stages of pregnancy, continuing for the first 12 weeks if they:
- (or their partner) have a neural tube defect
- have had a previous pregnancy with a neural tube defect
- (or their partner) have a family history of neural tube defects
- have diabetes type 1 or 2
- have epilepsy Epilepsy in Pregnancy Green-top guideline No. 69 RCOG or take anti-epilepsy medication
- have a BMI 30kg/m2 or greater RCOG Green-top Guideline No.72
- Individuals taking sulfasalazine
- Individuals treated with low dose methotrexate (≤25mg/ week) within one month prior to conception.
- Individuals treated with low dose methotrexate at time of conception, note- these individuals should be advised to stop methotrexate immediately and referred to their specialist for urgent review.
GP’s should also prescribe for people who may become pregnant/ planning pregnancy ideally 3 months prior to conception and throughout the entire pregnancy for:
- Individuals with sickle cell disease, thalassaemia or thalassaemia trait
For public communications in pregnancy for RSV see the NHS Somerset RSV & Flu Vaccinations Pregnancy page.
Vaccinations - Maternity (somersetft.nhs.uk)
Vaccinations in pregnancy - NHS (www.nhs.uk)
Five reasons to get the COVID-19 vaccine if you’re pregnant
Whooping cough: vaccination in pregnancy programme resources - GOV.UK Last updated: 26 June 2024
Vitamin D supplements should be taken daily for the duration of pregnancy, ideally from 3 months prior to conception if possible.
Vitamin D should then continue for the duration of lactation more information can be found on the Somerset Medicines Management Lactation page.
Advise people planning pregnancy, those who are pregnant and/ or breastfeeding and chestfeeding to take Vitamin D 10 micrograms per day. PH56 Vitamin D: supplement use in specific population groups.
Supplementation of vitamin D is suitable for self-care unless the patient is deficient-
Treatment of deficiency (Vitamin D <25nmol/l) formulary options available on the Somerset Prescribing formulary. An upper daily dose of 4,000iu daily for 10 weeks is preferred while pregnant more information can be found on the Specialist Pharmacy Service website:
Dosing and monitoring for treatment of Vitamin D deficiency in pregnancy
Healthy Start vitamins are available for families who qualify for free, see how to apply. Healthy Start women’s vitamin tablets contain folic acid and vitamins C and D (Children’s drops also available). FAQs. The application form must be signed by a midwife, health visitor, doctor or nurse.
Health in Pregnancy
Allergic rhinitis in pregnancy access information from Specialist Pharmacy Service for safety and first line choices in pregnancy – Hayfever or allergic rhinitis: treatment during pregnancy
Specialist Pharmacy Service – Asthma: treatment during pregnancy (under review)
NHS Somerset Respiratory webpage
Formulary Chapter 3: Respiratory system
1.12.1 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. [BTS/SIGN 2019]
1.12.2 Advise anyone who is pregnant and who smokes about the dangers for themselves and their babies and give appropriate support to stop smoking. See the NICE guideline on tobacco for more information. [BTS/SIGN 2019]
1.12.3 Advise using the following medicines as normal during pregnancy:
- short-acting and long-acting beta2 agonists
- inhaled corticosteroids
- oral theophyllines. [BTS/SIGN 2019]
1.12.4 Offer oral corticosteroids during pregnancy if needed to treat exacerbations of asthma. Advise that the benefits of treatment with oral corticosteroids outweigh the risks. [BTS/SIGN 2019, amended BTS/NICE/SIGN 2024]
1.12.5 If leukotriene receptor antagonists or long-acting muscarinic receptor antagonists are needed to achieve asthma control, they should not be stopped during pregnancy. [BTS/SIGN 2019, amended BTS/NICE/SIGN 2024]
Specialist Pharmacy Service – Constipation: treatment during pregnancy (under review)
Avoid stimulant laxatives in pregnancy.
Scenario: Adults | Management | Constipation | CKS | NICE
Constipation - BUMPS from the patient arm of UKTIS.
The MHRA published a report in March 2022 showing no safety concerns with the use of metformin in pregnancy.
Metformin and insulin remain the mainstay of medical treatments during pregnancy, alongside dietary and individualised treatment options.
All other antidiabetic medications should be reviewed urgently. GLP1 medication and tirzepatide should not be used in pregnancy.
To see information on DMARD treatment including MHRA warnings see the Shared Care and PGDs - NHS Somerset ICB page for:
For disease-modifying anti-rheumatic drugs (DMARDs) in rheumatology/ gastroenterology/ neurology and dermatology conditions:
• Azathioprine in dermatology/ gastroenterology/
rheumatology/ neurology patients
• Hydroxychloroquine in dermatology/ rheumatology patients
• Leflunomide in rheumatology patients
• Mercaptopurine in gastroenterology patients
• Methotrexate tablets and subcutaneous injection in
dermatology/ gastroenterology/ rheumatology/ neurology
patients
• Leflunomide & methotrexate combination in rheumatology
patients
• Penicillamine in rheumatology patients
• Sulfasalazine in gastroenterology/ rheumatology patients
NICE Clinical Knowledge Summary: Management of Dyspepsia in pregnancy
Self-care first line:
Patient information link: NHS Indigestion and heartburn in pregnancy
- Eat smaller meals more frequently (every 3 hours), do not eat late at night (or less than 3 hours before bedtime), and avoid known irritants (for example alcohol, caffeine, fruit juices and carbonated drinks, chocolate, and fatty and spicy foods). Keep a food diary to identify triggers.
- Try raising the head of their bed by 10–15 cm.
- Avoid medications that may cause or worsen symptoms, if appropriate (for example calcium-channel antagonists, antidepressants, and nonsteroidal anti-inflammatory drugs).
- Stop smoking (if applicable).
Antacids and alginates are recommended as first-line treatments if symptoms are relatively mild and are not controlled adequately by lifestyle changes suitable for self-care.
If symptoms are severe, or persist despite treatment with an antacid or alginate, consider prescribing an acid-suppressing drug.
Compatible formulary preferred proton pump inhibitors (PPIs) may be used during pregnancy when clinically indicated. Omeprazole is licensed for use in pregnancy, in May 2026 the licence for rabeprazole (Pariet®) was updated to remove the previous contraindication in pregnancy. The licence for esomeprazole states that it may be used with caution during pregnancy.
In addition, the UK Teratology Information Service (UKTIS) advises that PPIs as a class can be used at any stage of pregnancy where treatment is required. UKTIS: Use Of Proton Pump Inhibitors In Pregnancy
While product-specific licensing information should be considered when selecting a medicine for use in pregnancy, expert evidence-based resources should be used to support informed, shared prescribing decisions with your patient.
Update on MHRA review into safe use of valproate – Update on MHRA review into safe use of valproate 12/12/22:
The CHM has advised that no one under the age of 55 should be initiated on valproate unless two specialists independently consider and document that there is no other effective or tolerated treatment. Where possible, existing patients should be switched to another treatment unless two specialists independently consider and document that there is no other effective or tolerated treatment or the risks do not apply.
Valproate use by women and girls MHRA updated guidance 11/02/2021 – Information about the risks of taking valproate medicines during pregnancy.
2022/23 Community Pharmacy Contractual Framework National Clinical Audit – Reducing the potential for harm from valproate prescribing in patients of childbearing age who are biologically able to be pregnant.
Antiepileptic drugs in pregnancy: updated advice following comprehensive safety review MHRA January 2021 update.
Valproate use by women and girls March 2018 MHRA update on Information about the risks of taking valproate medicines during pregnancy.
General Medical Council: Discussing the risk of sodium valproate this case study developed by the GMC with the General Pharmaceutical Council and the Nursing and Midwifery Council highlights the risk of harm created by taking sodium valproate during pregnancy.
The Epilepsy medicines and pregnancy leaflet above, aims to help support patients in understanding the risks for epilepsy medicines in pregnancy. It contains important information, including do not stop taking epilepsy medicines until you have talked to your specialist, GP or epilepsy specialist nurse.
Specialist Pharmacy Service: Epilepsy: treatment during pregnancy signposts evidence based information on the treatment of epilepsy in pregnancy.
NHS Somerset formulary Contraception page
NHS Somerset formulary Mental Health page
Refer to the Somerset Traffic Lights System Document located on this page for details on individual drugs
Folate
Folic acid should be taken by all women and people assigned female at birth who may become pregnant to reduce the risk of having a baby with a neural tube defect.
Usually folic acid 400 micrograms daily should be started 3 months before pregnancy (where possible) and continued throughout the first 12 weeks of pregnancy, this is available over the counter and suitable for self-care.
Maternal and child nutrition: nutrition and weight management in pregnancy, and nutrition in children up to 5 years | Guidance | NICE advise that GPs should prescribe 5mg of folic acid a day for women and people assigned female at birth who are planning a pregnancy (3 months before conception where possible), or are in the early stages of pregnancy, continuing for the first 12 weeks if they:
-
(or their partner) have, or if there is a family history of, a neural tube defect or other congenital malformation
-
have had a previous pregnancy affected by a neural tube defect or other congenital malformation
-
have type 1 or type 2 diabetes
-
have a haematological condition that requires folic acid supplementation, such as sickle cell anaemia or thalassaemia
-
are taking medicines that can affect how folic acid is absorbed or metabolised (for example, people taking anti-epileptic medicines or medicines for HIV).
Epilepsy in Pregnancy Green-top guideline No. 69 RCOG
Individuals needing 5mg folic acid daily also include:
- Individuals taking sulfasalazine
- Individuals treated with low dose methotrexate (≤25mg/ week) within one month prior to conception.
- Individuals treated with low dose methotrexate at time of conception, note- these individuals should be advised to stop methotrexate immediately and referred to their specialist for urgent review.
GP’s should also prescribe for people who may become pregnant/ planning pregnancy ideally 3 months prior to conception and throughout the entire pregnancy for:
- Individuals with sickle cell disease, thalassaemia or thalassaemia trait
- See the NHS Somerset Shared Care protocol for DMARDs and the British Society for Rheumatology guideline on prescribing drugs in pregnancy and breastfeeding: immunomodulatory anti-rheumatic drugs and corticosteroids November 2022.
USE OF FOLIC ACID IN PREGNANCY – UKTIS
B12 Deficiency
For information on B12 deficiency, you can see links to guidelines on our Nutrition and Hydration - NHS Somerset ICB page.
Replacement formulation (IM or oral) should follow guidelines, if oral is indicated, 1mg cyanocobalamin daily should be prescribed in line with the NHS Somerset Formulary
Herbal medicines: safety during pregnancy information shared from the SPS
See our Shared Care and Patient Group Directions webpage for patient information leaflets on ‘Taking aspirin to reduce the risk of pre-eclampsia’, available in two different formats for printing purposes, for patients accessing the community pharmacy PGD. Includes the use of aspirin in patients who have low levels of placental protein (Low PAPP-A) identified by blood tests taken at the 11-14 week scan screening, as well as people with sickle cell disease.
Hypertension in pregnancy NICE Quality Standard and guidance.
Pregnant people at increased risk of pre-eclampsia at the booking appointment are offered a prescription of 75–150 mg of aspirin to take daily from 12 weeks until birth. NICE Quality statement 2.
GPs should prescribe 75-150mg of aspirin (unless contra-indicated) from twelve weeks of pregnancy until birth for people with one high risk factor, or more than one moderate risk factor for pre-eclampsia.
High risk factors include:
- hypertensive disease in a previous pregnancy
- chronic kidney disease
- autoimmune disease, such as systemic lupus erythematosus or antiphospholipid syndrome
- type 1 or type 2 diabetes
- chronic hypertension.
Moderate risk factors include:
- first pregnancy
- age 40 years or older
- pregnancy interval of more than 10 years
- body mass index (BMI) of 35 kg/m2 or more at first visit
- family history of pre-eclampsia
- multi-fetal pregnancy.
Hypertension in pregnancy: diagnosis and management Visual Summaries
- planning care for women at moderate and high risk of pre-eclampsia
- assessment of proteinuria and care plans
- chronic hypertension: pre-pregnancy advice
- chronic hypertension: antenatal care
- gestational hypertension: antenatal care
- intrapartum care and place of care
- criteria for choice of critical care level (hypertension, pre-eclampsia and eclampsia)
- follow-up care and postnatal review
- antihypertensive treatment during the postnatal period
- risk of long-term cardiovascular disease
- pre-eclampsia: antenatal care
- risk of recurrence of hypertensive disorders of pregnancy
Specialist Pharmacy Service: Hypertension: treatment during pregnancy
Intrahepatic cholestasis of pregnancy (ICP), previously known as obstetric cholestasis, is a pregnancy specific liver condition. ICP occurs when the flow of bile is impaired which causes bile acids to build up and flow into the bloodstream. ICP is associated with premature labour, foetal distress and, in severe cases, stillbirth, individuals who experience ICP may go on to develop liver disease. Identification and active management are important for improved outcomes for the pregnancy dyad.
For information on DMARDS used in pregnancy, see the Shared Care and PGDs - NHS Somerset ICB page for the DMARD shared care protocol - For disease-modifying anti-rheumatic drugs (DMARDs) in rheumatology/ gastroenterology/ neurology and dermatology conditions.
TREATMENT OF INTRAHEPATIC CHOLESTASIS OF PREGNANCY (OBSTETRIC CHOLESTASIS) – UKTIS
Intrahepatic cholestasis of pregnancy (ICP) - BUMPS - from the patient arm of UKTIS
Intrahepatic cholestasis of pregnancy Support with easy read materials can be found on the ICP Support website.
Acute care toolkit 15. Managing acute medical problems in pregnancy Nov 2019. This toolkit is intended to be used widely, including by front-line NHS Healthcare professionals and those involved in local and national planning and policy.
- Acute care toolkit 15 ACT pregnancy Nov19 237.67 KB
- Acute care toolkit 15 Appendices 552.86 KB
- Acute care toolkit 15 Flowcharts Nov19 383.07 KB
Please see the Mental Health Page for more information on Perinatal Mental Health in including NHS Somerset’s guide to preferred antidepressants while pregnant and lactating as well as further resources for healthcare professionals and parents.
Preconception advice for women with serious mental illness
Guide for healthcare professionals involved in the care of women with serious mental illness (SMI) in primary and secondary care, developed by King’s College London in partnership with Public Health England, NHS England and Tommy’s.
Perinatal Mental Health Treatment provides free evidence-based resources for new parents and clinicians.
Healthier Together provides maternal mental health patient information and resources.
Depression - antenatal and postnatal | Health topics A to Z | CKS | NICE
Also see the Mental Health Page for further links.
NHS Somerset netFormulary - Nausea and Vomiting
Nausea and vomiting of pregnancy
Nausea and vomiting are very common during pregnancy. Symptoms can range from mild nausea to frequent vomiting and is often referred to as "morning sickness", although symptoms can occur at any time of the day or night.
Symptoms are usually worst during the first trimester (up to 12 weeks of pregnancy). For most people, symptoms improve by 16–20 weeks, although some may continue to experience nausea and/ or vomiting throughout their pregnancy.
People will usually try self-help measures before seeking medical advice.
Ginger has traditionally been suggested, it may help with mild to moderate symptoms, but it is unlikely to be effective for moderate to severe nausea and vomiting and should not be recommended in the healthcare setting.
Antiemetics should be considered for individuals not managing their symptoms through self-care measures alone.
Hyperemesis Gravidarum (HG)
A small number of people develop a more severe form of pregnancy sickness called Hyperemesis Gravidarum (HG). HG can cause significant dehydration, weight loss, and difficulty carrying out normal daily activities, it can also have life long physical, and mental health effects on the individual and their family.
People with moderate to severe nausea and vomiting will require antiemetic medication, and may require treatment with fluids and hospital admission if symptoms are not controlled. Hospital admission may be necessary if symptoms are severe or do not respond to treatment provided in primary care or outpatient settings alone.
Acupressure may be used alongside medical treatment for symptom relief for any severity of symptoms, but it should not replace appropriate medical assessment and management.
Further Information and Support
- Nausea and vomiting in pregnancy while breastfeeding, including Hyperemesis Gravidarum- The Breastfeeding Network. This comprehensive factsheet explains pregnancy sickness and Hyperemesis Gravidarum, discusses treatment options during breastfeeding, and reflects the latest Royal College of Obstetricians and Gynaecologists (RCOG) Green Top Guidance 69 - February 2024. It also links to the Pregnancy Sickness Support charity, which provides practical advice and support for those experiencing pregnancy sickness. It may be a useful resource for individuals who aren’t breastfeeding an older baby or child still as it is a rich source of information including self-care, medical treatment and signposting information.
- Severe Vomiting in Pregnancy- NHS Patient website
- Nausea & vomiting from BUMPS Best use of medicines in pregnancy (BUMPS) from UK Teratology Information Service (UKTIS)
Clinical Guidance
- UKTIS statement on the use of ondansetron in the first 12 weeks of pregnancy, in Somerset it remains second line where first line treatments have failed, provided discussion is had with the parent over risks and benefits. Use the statement to share numbers for patients to make an informed decision
- RCOG GTG 69/ RCOG guidelines to the management of nausea and vomiting of pregnancy and Hyperemesis Gravidarum GTG69. See Appendix III for recommended antiemetic dosages for nausea and vomiting of pregnancy.
- NICE Guideline NG201: Antenatal care. This includes a summary of the advantages and disadvantages of different pharmacological treatments for nausea and vomiting in pregnancy (Table 1).
Medications recommended by NICE and RCOG for the treatment of nausea and vomiting in pregnancy are on formulary.
Primary Care First line options:
| Drug | Licensed indications | Doses for licensed indications | Is this licensed for nausea and vomiting in pregnancy? |
| Doxylamine/ pyridoxine (combination drug- brand Xonvea®) |
Nausea and vomiting of pregnancy |
Orally: starting dose of TWO tablets at bedtime on day 1. If symptoms persist, the dose can increase to TWO tablets at bedtime on day 2, increasing to ONE tablet in the morning and TWO tablets at bedtime on day 3 if necessary. The dose can increase to a maximum of ONE tablet in the morning, ONE tablet at lunchtime and TWO tablets at bedtime from day 4. Treatment should continue with regular dosing, not for when required use. If stopping, the dose should be gradually reduced to avoid rebound symptoms. Regular review recommended. |
Yes. |
| Promethazine hydrochloride | Nausea and vomiting | Orally: 12.5 – 25mg up to 4 times day | No, but established practice and used for many years. BUMPS – best use of medicine in pregnancy |
| Cyclizine | Nausea and vomiting | Orally: 50mg up to 3 times a day | No, but established practice and used for many years. BUMPS – best use of medicine in pregnancy |
| Prochlorperazine | Severe nausea and vomiting | Oral tablets: 5-10mg given 2-3 times a day, max 30mg/day Buccal tablets: 3-6mg twice a day. |
No, but established practice and used for many years. BUMPS – best use of medicine in pregnancy |
Primary Care Second line options:
| Drug | Licensed indications | Doses for licensed indications | Is this licensed for nausea and vomiting in pregnancy? |
| Metoclopramide | Nausea and vomiting | Maximum duration of treatment: 5 days. Dose in adults >18 years of age and >60kg body weight: Orally: 10mg up to 3 times a day |
No, but established practice as second-line treatment for nausea and vomiting in pregnancy. BUMPS – best use of medicine in pregnancy |
| Domperidone | Nausea and vomiting | Maximum duration of treatment: one week. Doses for adults and adolescents ≥35kg: Orally 10mg given 3 times a day, maximum 30mg/day |
No, domperidone should only be used during pregnancy when justified by the anticipated therapeutic benefit. Domperidone 10mg Tablets – Summary of Product Characteristics |
| Ondansetron | Nausea and vomiting associated with chemotherapy, radiotherapy and post-operative |
Orally: up to 4-8mg twice a day RCOG guidance for use The Management of Nausea and Vomiting of Pregnancy and Hyperemesis Gravidarum ondansetron orally: 4–8 mg 6–8 hourly |
No, but established practice as treatment for severe nausea and vomiting in pregnancy. BUMPS – best use of medicine in pregnancy Small increased chance of cleft lip or cleft palate when taken in the first 12 weeks. This is an increase of 3 extra cases per 10,000 from a background prevalence of 11 in 10,000 to 14 in 10,000. Use in the First trimester if clinically necessary where first line treatments have failed with informed consent from the parent. |
SPS – Pain: treatment during pregnancy the Specialist Pharmacy Service have published signposting evidence based information on the treatment of pain in pregnancy.
Healthcare professionals are reminded systemic NSAIDs are contraindicated during the last trimester of pregnancy, and alerted to new advice that use from week 20 be avoided unless clinically required, due to risk of oligohydramnios and premature closure of the ductus arteriosus. See Non-steroidal anti-inflammatory drugs (NSAIDs): potential risks following prolonged use after 20 weeks of pregnancy from Specialist Pharmacy Service.
See our Thyroid Conditions webpage
The information and links provided are for guidance, clinical decisions remain the responsibility of the practitioner; the intention is to help prescribers find evidence based information and does not replace input from appropriate professionals or constitute medical advice for individual patients.
