Behind the Science: How Pregnancy History Informs Hormone Therapy

April 7, 2023

Interviewees: Tanvi Puri, Ph.D. Candidate, University of British Columbia, Graduate Program in Neuroscience, Faculty of Medicine Authors/Editors: Romina Garcia de leon, Shayda Swann (Blog Co-coordinators).

Published: April 7th, 2023

Could you briefly explain what your research is about? 

My research examines the effects of reproductive experience and hormone therapy and their interactions on the aging brain. Previous research shows that reproductive history, i.e. lifetime number of pregnancies and age of first pregnancy, can affect brain aging. Some of my work examines how the age of first pregnancy affects spatial learning and brain health in middle age. I also study how hormone therapy interacts with reproductive history. We’re interested in looking at hormone therapy because there's a well-documented decline in certain types of cognition during menopause. 

There have been opposing findings on the effects of hormone therapy. However, most papers yielding negative effects of hormone therapy didn't investigate the types of hormone therapy or the time treatment started. These factors could significantly affect the outcome of hormone therapies, and so my research is trying to tease some of that nuance apart, i.e., how does the age you were pregnant affect normal brain processes, cognition, or efficacy of hormone therapy in middle age?

Why should we pay more attention to this work? 

It’s important to study women's health and investigate female-specific factors to improve healthcare for all. Everybody–men, women, trans, and non-binary individuals– experiences changes to the brain with age. For example, genetics, lifestyle, or diet are all things that medical professionals invariably cover when taking a medical history. However, when prescribing things like hormone therapy, the age of the first pregnancy or even the number of pregnancies is not currently in the medical zeitgeist. 

Some of my preliminary work shows that, for individuals who have had reproductive experience or who have been pregnant in the past, hormone therapy can be beneficial, but for individuals who have not been pregnant before, it can be detrimental for certain types of cognition. If somebody is getting hormone therapy for spatial memory issues, they might need a different kind based on whether they've been pregnant in the past or not, and that treatment should be different if they’re struggling with, say, verbal recall. Clinically, I know that this is not in consideration at the moment. 

Could you highlight some important findings from your research?

My study design involves rats that were either pregnant at a young age or late adulthood and how they performed on a cognitive task in middle age that tested spatial learning and memory.  We also treated some of these rats with estradiol, which is one type of hormone therapy that may be prescribed to individuals as they undergo menopausal transition. 

We found that estradiol was detrimental to overall learning in rats that were pregnant at a younger age. However, this didn’t hold for animals that were pregnant at an older age, or those that were never pregnant. When we looked at cognitive flexibility, a different type of cognitive task, the results were dramatically different. In humans, this task might look something like trying to remember where your favourite pot is after you reorganize your kitchen.  We’re measuring how many times you opened the old cabinet before remembering to go to the new one. We found that estradiol is beneficial for this kind of learning, and this effect is salient in rats that were pregnant only at older ages. 

This means that estradiol can either deter or improve cognition based on the type of learning and when you were first pregnant! And ties into the previous question, because it is essential to consider reproductive history when looking for an effective treatment for certain conditions.

What impact do you hope to see with this work years from now? 

I think the broader goal of my work is the same as most people working in women’s health–to improve diagnoses and treatment for women (and trans and non-binary individuals).  There's a fundamental lack of education and awareness about the impact of female-specific factors, such as pregnancy. 

What keeps me up at night is the eternity it takes to see changes in the medical system. If we implement changes to the medical education system now and start talking about these issues to students in medical school, in all likelihood we’re not going to see them in practice for at least another 10 years. I think it’s very important that research looking into how female-specific histories can affect a variety of other conditions are linked together and not just in the minds of people doing this research. Because it's only through making this research public that we'll be able to improve outcomes.

First Nations land acknowledegement

We acknowledge that the UBC Point Grey campus is situated on the traditional, ancestral and unceded territory of the xʷməθkʷəy̓əm (Musqueam) people.

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