Clinical Practice Guidelines Antenatal care - Module I

10.3 Medicines

Page last updated: 02 April 2013

10.3.1 Prescription medicines

Prescribing medicines during pregnancy involves balancing the likely benefit to the pregnant woman against the potential harm to the fetus. Only a small number of medicines have proven safety in pregnancy and a number of medicines that were initially thought to be safe in pregnancy were later withdrawn. General principles include prescribing only well-known and tested medicines at the smallest possible doses and only when the benefit to the woman outweighs the risk to the fetus.

The Therapeutic Goods Administration has categorised medicines that are commonly used in Australia, taking into account the known harmful effects on the developing baby, including the potential to cause birth defects, unwanted pharmacological effects around the time of birth and future health problems (see Table 10.3).

Table 10.3: Therapeutic Goods Administration categorisation of medicines

Category Description of Medicines which come into a particular category
A
Medicines which have been taken by a large number of pregnant women and women of childbearing age without any proven increase in the frequency of malformations or other direct or indirect harmful effects on the fetus having been observed.
B1
Medicines which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have not shown evidence of an increased occurrence of fetal damage.
B2
Medicines which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals are inadequate or may be lacking, but available data show no evidence of an increased occurrence of fetal damage.
B3
Medicines which have been taken by only a limited number of pregnant women and women of childbearing age, without an increase in the frequency of malformation or other direct or indirect harmful effects on the human fetus having been observed. Studies in animals have shown evidence of an increased occurrence of fetal damage, the significance of which is considered uncertain in humans.
C
Medicines which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human fetus or neonate without causing malformations. These effects may be reversible. Accompanying texts should be consulted for further details.
D
Medicines which have caused, are suspected to have caused or may be expected to cause, an increased incidence of human fetal malformations or irreversible damage. These medicines may also have adverse pharmacological effects. Accompanying texts should be consulted for further details.
X
Medicines which have such a high risk of causing permanent damage to the fetus that they should not be used in pregnancy or when there is a possibility of pregnancy.

10.3.2 Over-the-counter medicines

As few medicines have been established as safe to take during pregnancy, a general principle of use is that as few should be used as possible. However, over-the-counter medicines may be useful for relieving symptoms of pregnancy such as nausea and vomiting (see Section 7.8), heartburn, constipation (see Section 7.9) and haemorrhoids.

Consensus-based recommendation

xii. Advise women that use of prescription and over-the-counter medicines should be limited to circumstances where the benefit outweighs the risk as few medicines have been established as safe to use in pregnancy.
xiii. Therapeutic Goods Administration Category A medicines have been established to be safe in pregnancy.

Practice point

ee. Health professionals should seek advice from a tertiary referral centre for women who have been exposed to Category D or X medicines during pregnancy.

10.3.3 Herbal medicines

The use of complementary therapies (including herbal medicines) is increasingly common in Australia (AMA 2002). Women may choose to use them to support wellbeing, because they are perceived to be ‘safe’ alternatives to pharmacological treatments or because they are part of traditional practices in pregnancy. However, there is a lack of evidence on the safety of complementary medicines during pregnancy and some are known to be harmful in the first trimester.

There is little evidence from randomised trials to support the benefits or safety of herbal medicines (preparations derived from plants) and, even if active ingredients have been studied in trials, supplements may contain other ingredients with unknown effects. Studies have identified harms associated with some European (Cuzzolin et al 2010) and Chinese (Chuang et al 2006) herbal medicines.

Practice point

ff. Few herbal preparations have been established as being safe and effective during pregnancy. Herbal medicines should be avoided in the first trimester.

10.3.4 Providing advice on medicines

Health professionals can support women in safe use of medicines by being well informed themselves and by providing advice on relevant information services. Current information on specific medicines in pregnancy is available from:
  • Therapeutic Goods Administration medicines in pregnancy database — Therapeutic Goods Administration website, which can be searched by name or classification level;
  • medicines in pregnancy information services in each State/Territory, which provide advice to health professionals and consumers on supplements, over-the-counter and prescription medicines (see Section 10.3.6); and
  • the National Prescribing Service website — NPS Medicinewise website, which publishes resources for health professionals and consumers, with an emphasis on quality use of medicines.

10.3.5 Practice summary — advising women about use of medicines in pregnancy

When — At antenatal visits
Who — Midwife; GP; obstetrician; Aboriginal and Torres Strait Islander health worker; multicultural health worker; pharmacist
  • Discuss use of medicines with women — Explain that while many medicines are not safe in pregnancy, they may be needed in some situations (eg to treat high blood pressure, epilepsy, depression) or relieve some symptoms of pregnancy. Advise women to tell the pharmacist that they are pregnant if they are purchasing over-the-counter medicines.
  • Discuss risks and benefits — If prescribing medicines, explain any risks to the fetus and the benefits of the treatment to the mother so that women can make an informed decision about the treatment.

10.3.6 Resources

Medicines in pregnancy information services for health professionals
Australian Capital Territory
ACT Drug Information Service
The Canberra Hospital
Garran ACT 2605
Phone: 02 6244 3333
Fax: 02 6244 3334

New South Wales
Mothersafe
Medications in Pregnancy and Lactation Service
Royal Hospital for Women
Randwick NSW 2031
Phone: 02 9382 6539 or 1800 647 848

Victoria
Royal Women’s Hospital
Medicines Information Centre
Cnr Grattan St and Flemington Rd
Parkville VIC 3052
Phone: 03 8345 3190
Fax: 03 8345 3195

Monash Medical Centre
Obstetric Drug Information
246 Clayton Road
Clayton VIC 3168
Phone: 03 9594 2361
Fax: 03 9594 2595

GPO Box 1061L
Hobart TAS 7001
Phone: 03 6238 8737
Fax: 03 6222 8029 or 03 6231 2905

Northern Territory
Northern Territory Drug Information Centre
Royal Darwin Hospital
PO Box 41326
Casuarina NT 0811
Phone: 08 8922 8424
Fax: 08 8922 8499

South Australia
Drugs in Pregnancy and Lactation Information
Service
Women’s and Children’s Hospital
72 King William Road
North Adelaide SA 5006
Phone: 08 8161 7222
Fax: 08 8161 6049

Western Australia
Obstetric Drug Information Service
King Edward Memorial Hospital for Women
374 Bagot Road
Subiaco WA 6008
Phone: 08 9340 2723
Fax: 08 9340 2713

Queensland
Royal Women’s Hospital
Obstetric Drug Information Service
Brisbane QLD
Phone: 07 3253 7300
Fax: 07 3253 3544

Queensland Drug Information Centre
Royal Brisbane Hospital
E Floor, Block 7
Herston Road
Herston QLD 4029
Phone: 07 3253 7098 or 07 3253 7599
Fax: 07 3253 1393

Tasmania
Drug Information Centre
Pharmacy Department
Royal Hobart Hospital

Websites

Information about specific medicines regarding safety during pregnancy is available from:

10.3.7 References

AMA (2002) Complementary Medicine. Australian Medical Association Position Statement.

Chuang CH, Doyle P, Wang JD et al (2006) Herbal medicines used during the first trimester and major congenital malformations: an analysis of data from a pregnancy cohort study. Drug Saf 29(6): 537–48.

Cuzzolin L, Francini-Pesenti F, Verlato G et al (2010) Use of herbal products among 392 Italian pregnant women: focus on pregnancy outcome. Pharmacoepidemiol Drug Saf 19(11): 1151–58.