New findings show that the level of exposure to hormones while still in the mother's womb can affect how masculine a baby will look in adulthood.

According to a study conducted in Australia by the Telethon Kids Institute, a baby exposed to an increased amount of testosterone can lead to developing more masculine features such as longer noses and wider brows.

The researchers analyzed the testosterone concentration of the blood in the umbilical cords taken from 97 men and 86 women when they were newborns. The analysis was done using 3D facial photography, which measured the distance between certain landmarks on the person's face for up to 12 measurements. The researchers are currently analyzing facial photos of some 100 subjects.

"We've been able to construct 3D models of the face and then measure it to sub-millimeter precision," Professor Andrew Whitehouse from the University of Western Australia and one of the researchers said. He added that, unlike a tape measure, 3D photography allows measurement of surface distance and facial curvature. The software allowed differentiation of male and female faces with high accuracy.

Results showed that, once the babies reached 21 to 24 years old, higher levels of testosterone in their umbilical cord blood resulted in having a more masculine facial appearance. The results of the analysis will be part of a long-term study that includes more than 180 participants whose mothers were recruited while still pregnant with the subjects.

"It was quite a breathtaking effect," said Whitehouse. "Higher levels of testosterone in the cord blood are actually related to more masculine facial features." Whitehouse added that this finding applies to both sexes. Therefore, females who were exposed to higher levels of testosterone while in the womb gain more masculine features.

Testosterone has always been thought of as the male hormone because it is the predominant hormone in influencing male-attributed characteristics, such as facial hair and bulky muscle growth. Previous studies have also linked increased testosterone to autism and aggressive, risk-taking behaviors.

Studies have proven that testosterone levels can influence male and female facial appearances during puberty as well, although Whitehouse believes that hormonal exposure in the womb has more impact.

"We tested pubertal hormone levels as well, and found that it was the prenatal levels that were more related to adult facial structure," Whitehouse said. He added that genetics and environmental factors may also affect testosterone levels during pregnancy. Overweight and obese women also tend to produce more testosterone.

Photo: Teza Harinaivo Ramiandrisoa | Flickr