Medication consumed by an expectant mother can be passed on to the foetus.

EVERYONE gets ill at some time or other. Sometimes, the condition is self-limiting and requires no medicine. At other times, medicine is required.

The pregnant woman’s circulation is intricately linked to that of the developing foetus’, through the placenta. Just like how the necessary nutrients for foetal development cross the placenta and get into the foetal circulation, medicine consumed by the pregnant woman will be passed on to the foetus.

The effect of a medicine on the developing foetus depends on the medicine itself and the stage of pregnancy. In general, most pregnant women are aware of the need to avoid taking non-essential medicine. Yet they are not spared from illnesses and minor ailments.

Pregnancy is divided into three trimesters lasting about 13.3 weeks each. Foetal development is at its maximum in the first trimester. Medicine taken during this time can lead to foetal malformations or birth defects. If the defect is substantial, it would result in a miscarriage.

The foetus grows during the second and third trimesters with the development of the foetal nervous system in the first trimester continuing into the second. Medicine taken during the second trimester can affect the foetal nervous system and foetal growth. The latter could lead to low birth weight.

Medicine taken in the last trimester can remain in the newborn’s body. The baby may not be able to deal with medicine in the same manner the mother can. This can lead to complications like breathing difficulties in the newborn.

Medicine taken by a pregnant woman can also affect the environment in her uterus. For example, some medicines lead to uterine contractions which can affect the blood supply to the developing foetus.

The maximal impact of medicine is often in the first trimester. Some are risky if taken in the first trimester but may be safe in the second or third trimesters. Others are safe in the first trimester but risky in the second or third trimesters. In general, the risks are least in the second trimester.

Safety

Before a prescription medicine is marketed, it is first tested in animals, including pregnant animals, to detect any problems. Then it is given to humans in clinical trials to check its effectiveness and efficacy for various conditions, and to identify any side effects.

Although tests of medicines in animals can identify potential problems, they do not always predict its effects on humans.

As a general rule, pharmaceutical companies do not carry out clinical trials in pregnant women because it is unethical to do so. This results in few medicines being licensed for use in pregnant women.

Once a medicine is marketed, its effect in pregnancy is monitored in various ways:

· Adverse event reports – Pharmaceutical companies, doctors and researchers are required to report any adverse events to regulatory bodies, such as the Drug Control Authority in Malaysia.

· Pregnancy registries – Some pharmaceutical companies conduct special studies called pregnancy registries. Pregnant women who have taken certain medication are recruited and their babies are compared after birth to the babies of women who did not take the medicine.

· Research that identify risk factors for birth defects and problems with medicine in pregnancy.

Information about the safety of medicine in pregnancy is usually obtained from practical experience. When a medicine has been used extensively for several years without reports of adverse effects on pregnancies, it can be concluded that it is not harmful. Information is also available from the accidental consumption of medicine by pregnant women and animal studies. Some of the former may not know they are pregnant. It is in this manner that some prescription and over-the-counter medicines are known to be safe and others, harmful.

However, there is still insufficient information about the safety of many medicine in pregnancy. When medicine is taken during pregnancy, the benefits and risks have to be considered. If the benefits to the pregnant woman are greater than the risks to the foetus, then the medicine may be consumed. If the risks to the foetus are substantial, alternative treatments have to be considered.

Sometimes, a pregnant woman has to take medicine to reduce the likelihood of harm to herself and/or the foetus. The conditions include high blood pressure (hypertension), diabetes mellitus, fits (epilepsy), asthma, blood clots in the veins or lungs (thromboembolism) and certain infections. When treating these conditions, the doctor will prescribe medicine that is the most appropriate and safe for the pregnant woman.

Dietary supplements and herbal products

Many dietary supplements and herbal products are produced from natural compounds. This has led many people to believe that they are harmless and safer than prescribed medicines, especially with the marketing strategies of some companies.

It must be remembered that the regulatory requirements for dietary supplements and herbal products, if any, are considerably less stringent than that of prescribed medicines. Furthermore, most of these products have not been subjected to animal studies or human clinical trials. As such, any woman who is pregnant or intends to get pregnant is advised to consult the doctor before taking such products.

Folic acid is the only medicine available over the counter that is important to take, prior to and during pregnancy. It is used by the body to make new cells. If a woman has sufficient folic acid in the body before she gets pregnant, some major defects of the foetal brain and spine called neural tube defects (NTD) can be prevented. A dose of 400 microgram should be taken daily by every woman intending to get pregnant and for the first trimester. If a woman or her spouse has spina bifida or a previous child was born with NTD, a higher daily dose of 5mg is recommended.

Minor ailments

The only way to minimise risks to the foetus is to avoid consuming all non-essential medicine, particularly in the first trimester. Consult the doctor or pharmacist before consuming any medicine, including dietary supplements and herbal products, during pregnancy.

This does not mean that pregnant women have to put up with minor pregnancy ailments. There are medicines that are safe to use in pregnancy. They will be discussed in the next article.

There are a number of essentials to remember for pregnant women:

  • In general, avoid all non-essential medicine.
  • Consult the doctor or pharmacist before consuming any medicine.
  • Some medicine sold over the counter are harmful to the foetus.
  • Dietary supplements and herbal products are not necessarily safe. Consult the doctor or pharmacist before consuming any.
  • Contact the doctor or pharmacist immediately if there are any unusual effects experienced after consumption of a medicine.

Source: Dr Milton Lum