Dr Michelle O'Driscoll: Advice around medication use in pregnancy

Most of us take medications of some kind - whether it’s to manage an ongoing condition, prevent illness, maintain health, or occasionally treat something short-term.

However, during pregnancy, our bodies are growing a baby, and medication use must be considered through a new lens: Is this safe to take for both myself and my developing baby?

If you’re planning a pregnancy or are already pregnant and need to, or are already taking medications, here are some important things to keep in mind.

Understand what counts as ‘medication’

The term ‘medication’ is broader than many people realise. We tend to think of prescription drugs and sometimes over-the-counter products, but we often overlook supplements and herbal remedies. These too can affect the developing foetus, as many substances can pass through the placenta and act in potentially undesirable ways. It’s important to review all of them with pregnancy in mind.

The type of drug matters

It’s important - and often reassuring - to know that medication use during pregnancy is not inherently harmful. Some medications are considered safe and even necessary, while others should be avoided. There is no one-size-fits-all rule; the decision depends on multiple factors, as outlined below.

The trimester matters

The impact a medication can have on a developing foetus often depends on the stage of pregnancy. For example, the first trimester is when most of the baby’s foundational development occurs, while the third trimester is when the baby is preparing for birth.

The effects of certain drugs may vary depending on the organ systems developing at the time. This timing plays a key role in determining whether a drug is appropriate.

How much passes through the placenta matters

The placenta acts to filter the blood that reaches a developing foetus. Waste and toxins are included here, as are medications. Different drug molecules are filtered to different degrees. Some drugs may be theoretically unsafe, but evidence may show that very little, if any, passes to baby due to filtration, and they therefore pose little or no risk. Others might get through in significant amounts - or need only a small amount to have a harmful effect.

Understanding this can guide more accurate risk assessments by your healthcare team.

Never start a medication without proper advice

Always consult your healthcare provider before starting any new medication in pregnancy. Never assume it’s safe. Patient information leaflets often defer to healthcare advice, as decisions usually involve weighing the benefits against potential risks.

Discuss your symptoms, possible alternatives, and the available safety data with your provider to make an informed decision.

Never stop regular medication without proper advice

Equally important is not stopping any ongoing medication without professional guidance. Many medications are essential for your health - and, by extension, your baby’s.

Conditions like epilepsy, hypertension, diabetes, or mental health disorders require ongoing treatment during pregnancy.

Work with your healthcare team to determine the best approach and to evaluate the risks and benefits together.

Plan ahead when possible

Ideally, pregnancies involving medication use should be planned in advance, giving time to adjust medications before conception if necessary. Of course, this isn’t always possible.

In the case of an unplanned pregnancy, your care team will act quickly to make any needed changes and support your health and the baby’s.

Medication during pregnancy is often necessary for both maternal and foetal wellbeing. Its impact depends on several factors, so it’s important to have open, informed discussions with your healthcare team.

Together, you can find the safest and most effective plan for you.