Medical Bulletin 24/May/2025

BMJ Open has published a protocol that sets a new gold standard for clinical lactation studies, addressing the ethical and scientific gaps in understanding drug safety during pregnancy and breastfeeding. The protocol is part of two ongoing clinical trials at Uppsala University’s Centre for Research Ethics & Bioethics.

Women who stop treatment during pregnancy or breastfeeding face a troubling dilemma, as they must weigh their desire to have children and breastfeed against poorly understood health risks.

Currently, 95% of all medicines lack sufficient safety data for use during pregnancy and lactation. Existing standards rely heavily on outdated animal studies and limited data, using pharmacokinetic/pharmacodynamic (PB/PK) models to estimate drug transfer to infants. The new protocol goes further by collecting and analyzing breast milk and plasma samples from both mothers and breastfed infants.

The trials focus on two commonly prescribed medications: prednisolone, used for rheumatoid arthritis, and metformin, used for type 2 diabetes. Samples are biobanked and analyzed for pharmacokinetics and drug transfer levels, with informed consent enabling future research and long-term follow-up on medication effects in infants.

Participants are recruited through clinical centers across Sweden, and samples are stored within a network of breast milk biobanks coordinated by BBMRI-ERIC, embedding the study in a larger European research infrastructure.

This research marks a crucial step toward resolving the ethical and clinical uncertainties faced by pregnant and breastfeeding women, offering a scientifically robust and ethically sound path forward.

“The lack of scientific evidence is an ethical problem for women and doctors, considering that around 70 percent of women need to use medicines sometime during their pregnancy. In many cases, women are recommended to refrain from breastfeeding or stop using their medicines. However, breastfeeding has benefits for both mother and child,” says Mats G. Hansson, senior professor of biomedical ethics at Uppsala University’s Centre for Research Ethics & Bioethics, head of two ongoing clinical trials.

Reference: Svedenkrans J, Hellgren K, Backlund K, et al. Determination of prednisolone concentration in human breast milk and plasma of breastfed infants: study protocol of a Swedish multicenter low-intervention clinical trial, BMJ Open 2025;15:e097898. doi: 10.1136/bmjopen-2024-097898

Can a Baby's Growth Pattern Predict Obesity?

A new study published in JAMA Network Open by the Environmental Influences on Child Health Outcomes (ECHO) Program reveals that early changes in body weight may predict a child's risk of developing obesity by age 9. Funded by the National Institutes of Health (NIH), the study tracked the BMI (body mass index) of 9,483 children across the United States from infancy through age 9, identifying two distinct growth patterns.

Researchers used longitudinal data from medical records, caregiver reports, and in-person and at-home measurements to track BMI changes and identify early signs of risk. The children were part of the national ECHO Cohort, a large-scale effort to understand environmental influences on child health.

Most children (89.4%) followed a typical BMI curve, which declined from ages 1 to 6 before gradually increasing. However, 10.6% of children exhibited an atypical pattern, where BMI remained steady between ages 1 and 3.5 and then rose sharply through age 9. This group was found to have a significantly higher likelihood of obesity by age 9, with an average BMI exceeding the 99th percentile.

The study also identified several early-life factors associated with increased obesity risk, including high birthweight, maternal smoking during pregnancy, high pre-pregnancy maternal BMI, and excessive maternal weight gain during pregnancy. These findings underscore the importance of prenatal and early-childhood health behaviours in shaping long-term outcomes.

“The fact that we can identify unusual BMI patterns as early as age 3.5 shows how critical early childhood is for preventing obesity,” said ECHO researcher Chang Liu, PhD, of Washington State University.

“Our findings suggest there are important opportunities to reduce childhood obesity, such as helping pregnant women quit smoking and manage healthy weight gain, as well as closely monitoring children who show early signs of rapid weight gain,” said Liu.

This study highlights the potential for early intervention to prevent obesity and reduce the risk of serious health conditions later in life.

Reference: Liu, Chang, M., et al. (2025) Early-Life Factors and Body Mass Index Trajectories Among U.S. Children in the ECHO Cohort. JAMA Network Open.

Universal Heart Health Advice Ignores Realities in Low-Income Countries: Study Finds

Global recommendations for heart health may not apply universally, especially in low- and middle-income countries, according to a new review published in the British Medical Journal Global Health. The study, led by Scott Lear, a cardiovascular disease expert from Simon Fraser University, concludes that one-size-fits-all guidelines often ignore the broader social and environmental contexts that shape heart disease risk. It calls for health policies that are more sensitive to local realities in order to be truly effective in preventing cardiovascular disease (CVD) worldwide.

Cardiovascular disease is the leading cause of death globally, with 80 percent of cases occurring in low- and middle-income countries. Yet international guidelines—such as engaging in 75 minutes of exercise weekly or consuming five servings of fruits and vegetables daily—are largely based on studies from high-income nations, says Lear, who is also the Pfizer/Heart & Stroke Foundation Chair in Cardiovascular Prevention Research.

“The world extends beyond high-income countries when we think about universal recommendations like 75 minutes of exercise each week or getting five servings of fruit and vegetables every day,” says Lear.

“There’s a stark contrast between a daily sidewalk stroll in Vancouver's West End and walking to work in New Delhi, the world’s most polluted city, where many people cannot afford to drive and public transit is lacking,” he adds. “We cannot assume that life is the same everywhere. The environments in which people live and the kind of work they do make a huge difference to their health.”

Drawing on data from the Prospective Urban Rural Epidemiology (PURE) study—which has tracked over 212,000 people in 28 countries since 2002—the review highlights how physical activity and diet vary dramatically by region and income. In many low-income settings, physical exertion comes from necessity, not leisure, and farmers often can't afford to eat the produce they grow. “For many of these farmers, getting the recommended minimum of five servings of fruits and vegetables a day would eat up 50 percent of their household income,” Lear notes.

The study urges global health leaders to rethink prevention strategies, tailoring them to the lived realities of communities most affected by cardiovascular disease.

Reference: Scott A Lear, Martin McKee, Perry Hystad, Blake Byron Walker, Adrianna Murphy, Michael Brauer, Marjan Walli-Attaei, Annika Rosengren, Sumathy Rangarajan, Clara K Chow, Salim Yusuf, Social factors, health policy, and environment: implications for cardiovascular disease across the globe, European Heart Journal, 2025;, ehaf212, https://doi.org/10.1093/eurheartj/ehaf212