Prescribing in Pregnancy

Mrs Newlywed was a regular patient at the practice, but this was the first time that Dr Young had met her, as Mrs Newlywed usually saw Dr Young’s colleague, Dr Old.

Mrs Newlywed told Dr Young that she would like to have her Implanon rod removed as she felt the time was right for her to have a baby. Mrs Newlywed had only booked a single appointment, and it was Dr Young’s usual practice to allow a double appointment for this procedure, as removal of Implanon can sometimes take a little time. Nevertheless, Dr Young wanted to be helpful, so she took the patient into the treatment room, and with her nurse’s assistance removed the Implanon without too much difficulty.

Mrs Newlywed was rather intense and had numerous questions and concerns about her planned pregnancy, including blood tests, Listeria, exercise during pregnancy and choice of hospital and obstetrician etc. Dr Young answered all Mrs Newlywed’s questions, and Mrs Newlywed left, with Dr Young feeling rather stressed as she was aware that she was now running quite a bit behind schedule.

A few weeks later, Dr Young received a letter of complaint from Mrs Newlywed.

Mrs Newlywed wrote:

"When I took my routine scripts for my blood pressure medication to the chemist, he told me that ramipril should never be used during pregnancy and may have harmed my baby, if I had become pregnant while taking it. Why did you not advise me to stop this medication when I saw you recently about pregnancy? I thought that you would have checked my records and medication as part of our discussion about me wanting to be pregnant. I can’t believe you have been so careless! I am also very disappointed with Dr Old for prescribing this medication in the first place and not warning me that it was not good in pregnancy!"

Dr Young realised that when she saw Mrs Newlywed, the entire consultation had taken place in the treatment room, and she had not checked the computer records until after Mrs Newlywed had left, when she just noted the details of the removal of the Implanon. She had not reviewed her past history, or regular medications, and Dr Young now noted that Mrs Newlywed’s most recent consultation was for repeat scripts for her medication for hypertension, which she had been on for quite some time.

Dr Young was aware that angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) are category D in pregnancy, and she was concerned that this had been a “near miss” in terms of adverse events.

Discussion

Medicine use in pregnancy and lactation

Recent notifications to MDA National have highlighted the need for all medical practitioners to review the use of all drugs in pregnancy and breastfeeding.

There is some value in the old adage that “all women between the ages of 15 and 50 years should be assumed to be pregnant,” and doctors should take care when prescribing to women in this age group.

The use of prescribed medicines, complementary medicines and substances of dependence has become more wide-spread in the general community and as a result many women trying to conceive and those who are pregnant or breastfeeding are exposed to prescribed, natural and illicit drugs.

It is the treating doctor’s responsibility to obtain a detailed history of all drugs that a patient is taking and to ensure the patient is aware of the safety of all substances they are using during pregnancy.

The Australian Drug Evaluation Committee (ADEC) Prescribing Medicines in Pregnancy and Therapeutic Goods Administration has set up a detailed assessment of all medications available on the PBS giving them a safety rating:

• 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 foetus having been observed.
• Category 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 malformations or other direct or indirect harmful effects on the human foetus having been observed. Studies in animals have not shown evidence of an increased occurrence of foetal damage.
• Category B2 - Medicines which have been taken by a limited number of pregnant women or women of childbearing age, without an increase in the frequency of malformations or other direct or indirect harmful effects on the human foetus having been observed. Studies in animals are inadequate or may be lacking. However, available data shows no evidence of an increased occurrence of foetal damage.
• Category 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 malformations or other direct or indirect harmful effects on the human foetus having been observed. Studies in animals have shown evidence of an increase of foetal damage, the significance of which is considered uncertain in humans.
• Category C - Medicines which, owing to their pharmacological effects, have caused or may be suspected of causing, harmful effects on the human foetus or neonate without causing malformations. These effects may be reversible.
• Category D - Medicines which have caused are suspected to have caused or may be expected to cause, an increased incidence of human foetal malformations or irreversible damage. These medicines may also have adverse pharmacological effects. Accompanying manufacture’s texts should be consulted for further details.
• Category X - Medicines which have such a high risk of causing permanent damage to the foetus, that they should not be used in pregnancy or when there is a risk of pregnancy.

The use of complementary and alternative medicines in pregnant and lactating women is growing. Patients may not perceive complementary medicine use as medicines. There is limited information on the safety and efficacy of most complementary medicines. In addition the preparations of complementary medicine are usually not standardised with its concentration and purity.

Women should be informed that the use of complementary medicine in pregnancy and lactation has not been subjected to scientific evaluation and that the risks to the developing foetus and breast fed baby are unknown (for example Echinacea).

The use of substances of dependence and alcohol should be discouraged during pregnancy. Illicit drugs are known to cause infertility, early miscarriage, premature labour, growth retardation and placental abruption. Alcohol is a known teratogen and the risks of alcohol related birth defects increases with the amount of alcohol consumed.

When counselling women of child-bearing age, pre-pregnancy, pregnant or lactating regarding drug use it is important to have easy access to the side effects and the safety of all substances she may be exposed to, so an informed decision can be made. Medical software packages will have the safety rating for medications readily available, as does MIMS. The main tertiary referral  hospital for women’s services in each state has a pharmacy department, whose staff are usually helpful if more specialised knowledge is required.

Postscript

Dr Young discussed Mrs Newlywed’s letter of complaint with Dr Old. At the next practice meeting they raised the issue with all the doctors at the practice, so they could all be more aware of prescribing to women in this age group. They also ensured that the practice software had warnings turned on for prescribing to women of childbearing age.  

With the assistance of MDA National staff, Dr Young replied to Mrs Newlywed’s letter. Mrs Newlywed took no further action and continued to attend the practice for management of her pregnancy.

Further information

• Royal Women’s Hospital. Pregnancy & Breastfeeding Medicine Guide. Available from:  rch.org.au/chas/pubs/index.cfm?doc_id=1003 Hale TW. Medications and Mothers’ Milk, 13th ed. Hale Publishing; 2008.