In recognition of International Women’s Day 2025, NDARC’s Medicines in Pregnancy research team has written about their body of work and the importance of their findings on the use and safety of medicines during pregnancy. While there is much more to women’s health research than reproductive health, there is no question that more research is needed to support informed decision-making among pregnant women. The evidence produced through this research program has helped countless women in Australia and overseas weigh up the risks and benefits of pharmaceutical treatment options during pregnancy.

The team – which includes Associate Professor Alys Havard, Dr Danielle Tran, Dr Annelies Robijn and Ms Bianca Varney – has studied medicines used in the treatment of substance use disorders (e.g. tobacco, alcohol and opioid use disorder) and medicines that have the potential to lead to dependence (e.g. opioid pain killers and stimulants used in the treatment of ADHD). Improved knowledge about the safety of these medicines has contributed to the prevention of alcohol and other drug related harm.

Why Medicines in Pregnancy research matters

Pregnant women are often excluded from clinical trials for various safety and ethical reasons, which means there is a lack of information about the effects of medicines on expectant mothers and their babies. Approximately 90% of pregnant women take at least one medicine, yet for many medicines we do not know whether they will be effective in treating the targeted health condition in a pregnant woman, what dose should be used, and whether they might be harmful to the baby or cause pregnancy complications.

This knowledge gap means women and their healthcare providers are often flying blind when making decisions about whether to use certain medicines during pregnancy. This often leads to conservative use of promising treatments among women who are pregnant or who have a chance of becoming pregnant, meaning health conditions may go untreated and pose serious health risks to the mother and/or baby. Conversely, use of medicines of unknown safety may result in serious harm to mothers and/or babies.

The power of real-world data for studying medicines in pregnancy

Given the ethical barriers to including pregnant women in clinical trials of medicines, real-world studies provide the best opportunity to obtain the evidence needed. Studies using real-world data allow us to learn from the experiences and outcomes of hundreds of thousands of pregnant women and their children. Real-world data include the information collected from everyday contacts with health and government services – for example seeing a family doctor or midwife, attending a hospital emergency department, getting a prescription filled at a pharmacy, giving birth at hospital or at home, applying for a birth certificate for a newborn, applying for income support, enrolling a child in school.

When records from these contacts are connected, via a technique called “record linkage”, the resulting datasets offer unique advantages that make them especially powerful for understanding the use and safety of medicine in pregnancy. A particular strength of these linked datasets relates to their coverage, as they usually include information for the whole population of women who gave birth in a geographic area, rather than being restricted to those who volunteer to participate in research. This helps with ensuring the research findings are applicable to the whole population. Additionally, the large number of pregnancies included means we can investigate the risk of rare but severe side effects, or infrequently used medicines, that smaller studies might miss.

NDARC’s Medicines in Pregnancy research

NDARC’s Medicines in Pregnancy research program uses real-world data to examine the extent to which certain medicines are used during pregnancy and determine the safety (and in some cases effectiveness) of using these medicines during pregnancy. We specialise in research on medicines used in the treatment of substance use disorders and medicines that have the potential to lead to dependence. The goal of our research is to provide clear evidence about medicine safety and effectiveness so women and their doctors can make confident, well-informed decisions. The evidence we produce on the extent of medicine use during pregnancy is important for informing whether policy or clinical practice changes might be needed to change the levels of use and associated health outcomes.

We achieve this by analysing linked real-world data from New South Wales. We often combine our results with those from other Australian states and other countries to further increase the size of the study. We specialise in research on medicines used in the treatment of substance use disorders and medicines that have the potential to lead to dependence.

What have we found?

As an example, we have conducted a series of studies on quit smoking medicines, which include nicotine replacement therapy, varenicline and bupropion. We have examined their use, effectiveness and safety during pregnancy. This research was needed because smoking is the leading cause of poor maternal and child outcomes. The lack of clear evidence on the safety of these therapies means pregnant women may be missing out on a therapy that has the potential to help them quit smoking. In these studies, we collaborated with international researchers and analysed data from NSW, New Zealand, Sweden, and Norway, with a combined 5.2 million birth records. We found no evidence of a higher risk of major congenital anomalies among babies exposed to these medicines during gestation. The findings (due for release in April 2025) should reassure pregnant women who need help quitting smoking. They are also helpful for doctors and other healthcare providers when discussing the benefits and risks of smoking cessation therapies with patients and better support women to make informed choices about quitting during pregnancy.

Our work on medicines that have the potential to lead to dependence include our studies on the use of opioid pain killers. Pain is a common issue in pregnancy, yet women and their doctors have limited choices for safe pain management. We are studying whether taking pain killers during pregnancy might harm the mother, her baby, or affect the baby's brain development. We first investigated if opioids increase the risk of congenital anomalies by collecting all the available research on this topic and combining their results using a special mathematical method known as a meta-analysis. We found that there is no big increase in the risk of congenital anomalies. However, not all the studies we included were well-designed, and some had important methodological issues that may have biased the results. This highlighted that better quality research is needed in this area. We are also studying whether use of opioid pain killers during pregnancy might lead to problems for the mother or her child, including premature birth, low birth weight, or early separation of the placenta from the womb. Finally, we also have a study which examines if taking opioid pain killers during pregnancy might affect brain development in children. We’re doing this by comparing results of school-based tests in numeracy and language (NAPLAN) between children who were exposed to opioids in the womb versus children who were not

Beyond these specific examples, we have also completed studies on the safety of medicines for treatment of alcohol dependence and psychostimulant medicines (used in the treatment of ADHD) during pregnancy. We are also undertaking studies on the use and outcomes of methadone and buprenorphine for the management of opioid dependence among pregnant women.

Conclusion

Real-world data offer a unique and innovative approach to answering questions about medicines in pregnancy. The NDARC Medicines in Pregnancy research program generates high quality evidence on the use of medicines during pregnancy and the associated risks and benefits. We have generated evidence specifically for medicines used in the treatment of substance use disorders and medicines that have the potential to lead to dependence. This evidence empowers women and their doctors to make informed treatment decisions, ultimately reducing alcohol and other drug related harm and improving health of mothers and babies.

*Note that although we use terms which describe gender throughout the webpage content, including woman, mother, and maternal, our focus is on the biological sex. The information provided here should be considered inclusive of individuals who are pregnant or who have given birth but may not identify as women.

This research program was made possible through two grants from the Australian National Health and Medical Research Council (#1028543, #2010778). The NDARC Medicines In Pregnancy research program is conducted in partnership with the National Health and Medical Research Council Centre for Research Excellence in Medicines Intelligence (#1196900).