Crisis-induced maternal psychological stress may affect fetal development and birth outcomes.

Fetal development is a critical stage that can have lifelong effects. Nevertheless, the effects of maternal psychological stress on the fetus have been difficult to identify, primarily because stressful events often produce psychological and physiological consequences that directly affect mothers and their children. Natural disasters serve as important case studies for understanding the impact of maternal psychological health on the growing fetus, but it remains difficult to examine the isolated, specific impact of maternal psychological trauma on the child.

To address this gap, Associate Professor Rong Fu of the Faculty of Commerce of Waseda University, Japan, and Visiting Scholar of the Columbia Population Research Center, Columbia University, USA, along with Associate Professor Yunkyu Sohn of Seoul National University, Korea, Assistant Professor Yichen Shen of Kanagawa University of Human Services, Japan, and Professor Haruko Noguchi of Waseda University, examined a natural disaster that generated widespread concern far beyond its direct physical impact: The Fukushima nuclear power plant accident that occurred. March 15, 2011 Researchers studied the effects of maternal anxiety about radiation exposure on their fetuses. Their findings were published online on March 7, 2026, and are scheduled to appear in Volume 107 Journal of Health Economics On 1 May 2026.

What inspired Fu to do this study? she explains, “While living and working in Japan, I saw firsthand how deeply the Fukushima accident shocked the public, especially pregnant women and young mothers, even in areas far from any physical danger. Fukushima’s unique geography created a rare scientific opportunity to answer whether fear alone could harm a developing fetus.”

As part of the study, the team looked at three birth cohorts covering approximately 1.1 million births. The ‘prenatal’ exposure group included children who were in the uterus Born during and after the accident. The ‘postnatal’ exposure group also included children born before the accident. The ‘placebo’ group included people who were born during the same period as the postpartum group but in the previous year. Researchers have developed a new measure of radiation anxiety using Google Trends data to examine whether birth outcomes systematically worsen as the intensity of anxiety increases across geographic areas.

They found that premature births were 17–18% more common in the prenatal group compared to the postpartum and placebo groups. The weight at birth was on average 22 to 26 grams less. The rates of very low birth weight (VLBW) and extremely low birth weight (ELBW) were approximately 50% and 77% higher, respectively, than the other groups.

Researchers analyzed differences in Google searches about nuclear power plants between March 12 and April 11, 2011, and compared them to the same period in 2010 to create a search popularity index (SPI) for each prefecture as a measure of radiation-specific concern. Regression analysis showed that radiation-specific anxiety accounted for 72–79% of the difference in preterm births and 28–37% of the difference in mean birth weight between preterm and other groups. Radiation concerns played an even larger role in the difference in VLBW and ELBW rates. “Whether by triggering premature delivery among at-risk fetuses or by exacerbating growth restrictions in vulnerable populations, radiation-related psychological stress has significantly increased the incidence of severe birth outcomes associated with elevated risks of permanent developmental challenges.” Fu explains.

Interestingly, the effect of radiation anxiety on birth outcomes was strongly associated with socio-economic factors. Children born to mothers with university degrees or families in the top 25% income group were least affected. “Higher education may provide benefits through better access to accurate information about radiation risks and stronger coping resources, while higher household income may enable access to private health care and greater flexibility in responding to perceived threats.Fu notes.

Although it is difficult to create population-level measures of anxiety, the researchers say they were encouraged by the effectiveness of the SPI as a proxy. He believes the same strategy can be used to measure the invisible psychological effects of other large-scale crises, including the COVID-19 pandemic and climate change.

Overall, these findings highlight the effects that crisis-induced psychological stress can have on fetal development and birth outcomes. In addition to providing material assistance, disaster response protocols should prioritize clear communication that reduces fear and uncertainty. Psychological counseling should also be made available to pregnant women to help prevent intergenerational health consequences.