Lasting impact of mother’s diet during pregnancy revealed in rationing study

Babies whose mothers had greater access to sugar during pregnancy—specifically in 1949, when sugar consumption spiked due to the temporary end of confectionery rationing—grew up to have lower body weight and ate less sugar later in life, a new University of Bristol-led study has found.

The study, published in PNAS Nexus, looked at how a mother’s sugar intake during pregnancy might affect her child’s health later in life.

The researchers focused on a unique U.K. event. On 24 April 1949, after seven years, the British government ended confectionery rationing, leading to nationwide lines and a surge in demand for chocolate and sweets. People—including pregnant women—were desperate to indulge. Demand far outstripped supply, overwhelming the confectionery industry. As a result, some shops had to close, and by 13 August 1949, rationing was reintroduced.

However, the event provided a unique opportunity for researchers to study the effects of prenatal sugar exposure on long-term health outcomes.

The research team used health and lifestyle data from between 36,000 and 85,000 UK Biobank participants born between April 1947 and May 1952 to see how being exposed to more sugar in the womb influenced outcomes later in life.

They looked at a range of factors, including heart disease, body weight, height, diabetes, diet, education, and birth weight and found that the high-sugar diet had left a long-term mark on babies’ lives.

The researchers revealed that people exposed to the 1949’s sugar spike in the womb had lower BMIs in adulthood and performed better in school, completing, on average, 1.8 more months of education. These individuals also consumed 0.9% less sugar. Furthermore, those who were genetically “predisposed” to a sweet tooth benefited more from derationing, further lowering their sugar intake in later life.

Stephanie von Hinke, Professor of Economics from Bristol’s School of Economics and the study’s lead author, said, “Post-war food rationing ended 70 years ago in the U.K. Our research reveals that this era of food history left a surprising legacy that’s still with us today.

“Our results align with the concept of ‘fetal programming,’ where prenatal conditions, including diet, impact long-term health and behavior.

“In other words, the high-sugar diet of 1949 helped these babies cope with the high-sugar world in which we now live.

“Another theory is that the treats helped mothers de-stress. Perhaps this happiness allowed mothers to bond better with their newborns, helping babies’ development.”

However, the researchers caution against the effects of a sudden, temporary increase in sugar consumption, like the one observed in 1949.

Professor von Hinke, who researches the economics of health and diet, added, “This study does not support a high-sugar diet in pregnancy. The 1949 diet was very different from what it is now, with many other foods being rationed.

“Our results clearly show that what a mother does during pregnancy—what she eats, how much she smokes and drinks, and how happy she is—can affect the child in later life when they are 50, 60 or 70 years old.”