How many extra calories does a person need during pregnancy?

Pregnancy places a lot of extra strain on the body, requiring more food than usual over the course of nine months to support the pregnancy and the growing baby. 

But exactly how many calories does it take to grow a baby?

It turns out that estimates range widely — from about 50,000 to nearly 85,000 extra calories over the course of an entire pregnancy. Those are additional calories on top of what that person would need if they weren't pregnant.

"I would say that, for most women, 50,000 calories is going to be a gross underestimate," said Herman Pontzer, a professor of evolutionary anthropology and global health at Duke University. "I think, for most, it's going to be more like 70,000 … or even more."   

Related: How calories are calculated: The Science behind your food

Scientists have arrived at these numbers using different methods. For instance, a 2024 study published in the journal Science devised a formula for calculating the calorific cost of pregnancy for many species across the animal kingdom.

The team was led by Samuel Ginther, who was a doctoral student at Monash University at the time of the study. The researchers worked out the reproductive cost of 81 species, ranging from microscopic, aquatic animals to large mammals, including humans.