Polypharmacy in pregnancy

What is polypharmacy?

Polypharmacy refers to people taking two or more different prescription medications at the same time. It has been increasing over the last 30 years, partly due to more health conditions being diagnosed, and also to more drugs being available.

Side effects are a possible problem for anyone taking prescription medicine, and it is a bigger issue for people who are taking two or more medicines. They may also have problems caused by the interaction between different medications.  We are studying the impact of polypharmacy on people with a variety of health conditions, to help us develop ways to combat the problems of taking so much medication.  

Why focus on polypharmacy in pregnancy?

Doctors, midwives and researchers don’t have a good understanding of how much polypharmacy affects pregnant women and birthing people and their babies.  This is mainly because new medication is rarely tested on pregnant women due to concerns about the possible impact on the unborn baby. We do know that the changes that occur in the body during pregnancy mean that medications may not have the same effect as they do in someone who is not pregnant. Conversely, due to the evidence gap, it can also be harmful for pregnant women with long term health conditions to stop their regular medications.

MuM-PreDiCT is working to address this gap in knowledge, with a particular focus on pregnant women with two or more long term health conditions.

What have we discovered so far?

We have reviewed earlier research studies looking at polypharmacy in pregnancy. We found that overall, one in five pregnancies were reported to be affected by polypharmacy.

We then analysed GP electronic health records of over 800,000 pregnancies that occurred in the UK between 2000 and 2019. We found that the number of medications prescribed during pregnancy has increased over the last 20 years. About a quarter of all pregnant women were prescribed two or more medications.  And of the women who had two or more long term conditions, more than half were prescribed two or more medications during pregnancy.

The most commonly prescribed medications in pregnancy are:

  • antibiotics
  • antidepressants
  • painkillers
  • iron
  • laxatives
  • inhalers
  • anti-inflammatory creams/gels/ointments

When we looked at the patterns of polypharmacy, we found two main groups:

  • Inhalers are commonly prescribed with antidepressants, antihistamines, anti-inflammatory creams/gels/ointments, emollients and steroids.
  • Antidepressants are commonly prescribed with medications for heartburn and acid reflux, and thyroid disorders.

What’s next?

We will look more closely at how polypharmacy affects the health of pregnant women and their babies, both during and after pregnancy. We will conduct further studies to look at whether certain combinations of medications increase or decrease the risk of pregnancy complications such as pre-eclampsia, gestational diabetes, and premature delivery or health conditions in the baby, such as birth defects.

Knowing the potential benefits and harms of consuming medications during pregnancy will help pregnant women and their health care professionals to make informed decisions about whether to continue or start medications in pregnancy.

Take home points

Multiple medications are commonly prescribed in pregnancy, and more so among those women with multiple health conditions. Women contemplating pregnancy, and the health professionals caring for them, have to weigh up the possible benefits and harms to both the mother and her baby of continuing with or stopping pre-pregnancy medications, and of starting new medication during pregnancy. Further research is needed to understand the potential effects of medications that are commonly prescribed together.

Compiled by Anuradhaa Subramanian, Ngawai Moss, Katherine Phillips, Rachel Plachcinski, Siang Ing Lee.

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