These hips don’t lie – women with hourglass figures tend to be more intelligent and have smarter kids, a new study says.

Researchers have even come up with a scientific explanation for their theory – and for why men prefer voluptuous women with large hips and small waists.

It’s all about omega-3 fatty acids and a woman’s waist-to- hip ratio, or WHR – a mea surement that, according to an online calculator offered by Rush University Med ical Center in Chicago, “looks at the proportion of body fat stored on your waist compared to that stored at your hips and buttocks.”

You calculate it by dividing the waist circumference by the hip circumfer ence.

The lower the WHR, the better, according to the study by William Lassek of the University of Pittsburgh and Steven Gaulin of the University of California at Santa Barbara.

The study found that women who had a larger difference be tween their waist and hip mea surements scored higher in tests than did those with “apple-shaped” bodies.

“Women with lower WHRs and their chil dren have significantly higher cognitive test scores,” their study found.

They say that’s because the fat on a woman’s hips and thighs contains omega-3 fatty acids, which help in “critical brain-building” – and the curvier the hips, the higher the level.

The fat around the waist has higher qualities of omega-6 fatty acids, less helpful to brain growth.

“Shapely hips and thighs hold essential nutri ents that nurse brains and could produce smart kids, too,” Gaulin told London’s Telegraph.

That could explain why other studies have shown that men in Western countries “prefer women with both a low WHR [0.6 to 0.7] and a low body-mass index [17 to 20],” the researchers said.

“Men respond because it’s reproductively im portant,” Lassek said.

If that’s the case, a completely unscientific look at Hollywood shows that Harvard-educa ted actress Mira Sorvino scores a low WHR of .69 based on estimated measurements of a 24-inch waist and 35-inch hips.

By contrast, actress Keira Knightley, based on estimated online measurements of a 25-inch waist and 33-inch hips, would score a .76 WHR.

The researchers tested their thesis by look ing at data from a study of 16,325 women aged from birth to 90. The results will appear in the journal Evolution and Human Behavior.

rita.delfiner@nypost.com