Mona Lisa, the woman depicted in Leonardo da Vinci's 16th century masterpiece, was either pregnant or had recently given birth when she sat for the painting, a French art expert said Wednesday.

"Thanks to laser scanning, we were able to uncover the very fine gauze veil Mona Lisa was wearing on her dress. This was something typical for either soon-to-be or new mothers at the time," Michel Menu, research director of the French Museums' Center for Research and Restoration, said on LCI television.

Menu said a number of art historians had suggested that she was pregnant or had just given birth.

CountryWatch: France

Researchers have established that the picture was of Lisa Gherardini, wife of obscure Florentine merchant Francesco del Giocond, and that da Vinci started painting it in 1503.

The name Mona Lisa is the equivalent of "Madame Lisa." La Joconde, as the painting is referred to in many countries, is the French version of her married name.

The French art expert said all the secrets behind the enigmatic painting have yet to be revealed.

"Our laboratory is trying to uncover da Vinci's techniques. We particularly want to understand how he painted his shadows, the famous 'fumato' effect," Menu said.

The artist brought the painting to France in 1517. It has been in the Louvre Museum since 1804.

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