Her research was brought to the attention of non-economists through the Wall Street Journal, the book SuperFreakonomics, and her 2007 TED Talk.

Oster is the author of four books, Expecting Better, The Family Firm,[3] The Unexpected, and Cribsheet, which discuss a data-driven approach to decision-making in pregnancy and parenting.

In 2005, Oster published a dissertation for her economics Ph.D. from Harvard University, which suggested that the unusually high ratio of men to women in China was partially due to the effects of the hepatitis B virus.

"[16] Oster noted that the use of hepatitis B vaccine in 1982 led to a sharp decline in the male-to-female birth ratio.

[9] In April 2008, Oster released a working paper "Hepatitis B Does Not Explain Male-Biased Sex Ratios in China" in which she evaluated new data, which showed that her original research was incorrect.

[18] In a 2007 TED Talk, Oster discussed the spread of HIV in Africa, applying a cost-benefit analysis to the question of why African men have been slow to change their sexual behavior.

[34][35][36] Secretary of Education Betsy DeVos and the CDC cited Oster's work as a reason to open schools during the pandemic.

[39] In May 18, 2021, Oster published another piece in The Atlantic titled "Your Unvaccinated Kid Is Like a Vaccinated Grandma", which generated much heated response.

[40] Other critics emphasized Oster's misinterpretation of public health principles, failing to understand that vaccination is not simply to reduce individual risk of hospitalization and death, but stop the spread of disease as well[41] In September 2021, Oster launched the Covid-19 School Data Hub which includes information on virtual and in person status of schools across 31 states.

"[42] On October 31, 2022, The Atlantic published an opinion piece written by Oster in which she called for "amnesty" following the COVID-19 pandemic, citing the "tremendous uncertainty" surrounding topics such as the virus, face masks, social distancing, school closures and COVID-19 vaccines.