During my time as chair of the PRGLAC task force, I worked with and spoke to industry representatives and those in the private sector about the barriers to gathering data on medicines in pregnancy. One of the key things I kept hearing (something that we as clinicians are very aware of) is that it’s very uncommon for there to be medications that are specially tested in pregnant women. And for lactating women the problem is doubled, with incredibly limited information. And yet, we routinely prescribe medications during pregnancy and lactation. It’s a complex area: on one side, people say, “You should not test in pregnant or lactating women because of the potential risks and liability.” But you hear a similar argument on the other side – “in pregnancy, it’s very important to know what would be appropriate to take and what to avoid, because of the developing fetus.”
The reality, in the US at least, is that if a medication is approved for women of reproductive age for a condition that continues in pregnancy – such as hypertension or asthma – it is being used on-label, as described by representatives from the FDA at the PRGLAC meetings. But we have limited or no dosing recommendations and limited data, even though we know that a women’s physiology during pregnancy and lactation is different – blood volume doubles, there’s change to the binding proteins in the blood, GI transit time is different, as are kidney and liver function… and all of these changes could affect how a drug is bound, processed or cleared by the body.
In essence, when a new drug is being developed, if the drug is aimed at women of reproductive age then it is likely to be used by pregnant women whether intended or not. For example, if a new drug is being developed for seasonal allergies, it would not be surprising if some women got pregnant while taking the medication. This should be considered when designing the study – to include following women who have become pregnant or who are lactating. Having more information about what dosing changes may need to be made for pregnant women, or if there are any safety concerns for women who become pregnant, would be beneficial, including for healthcare providers seeking to advise patients, and the women themselves.
I have been involved in many clinical studies involving pregnant women – and it’s not as difficult as some might think. There is an ongoing maternal/fetal medicine unit network of sites across the US that performs clinical trials and studies in high risk and normal pregnancies, trying to optimize outcomes. These include randomized controlled trials, observational studies, and therapeutic interventions; one example was a trial of thyroxine in the setting of subclinical hypothyroidism. The important aspects are to ensure that the women enrolled in the trial understand why the trial is being done, what their participation means, and providing staff who can answer their questions and facilitate their participation in the trial, if they are interested.
My advice is to evaluate each trial and study and start with consideration of inclusion. It is important to scrutinize why women are excluded when the study is initially designed and determine if they truly must be excluded and, if so, why? Not to simply assume from the outset that exclusion is the best course of action. I’d like to see us move towards a mindset where we begin with the assumption that pregnant and lactating women should be included in studies and trials, unless their removal can be fully justified. Pregnant women shouldn’t be an afterthought – we need to build their needs in from the beginning of drug and therapy development.
Catherine Spong is Professor and Vice Chair, Obstetrics and Gynecology; Division Chair, maternal-fetal medicine UT Southwestern Medical Center, Dallas, Texas and Former Chair of Prglac.
