If you caught Tully recently, you saw Charlize Theron portray a woman who experiences the highs, but also the lows of life as a new mother.
The comedy-drama alludes to how, following pregnancy, women have reported experiencing a whole host of changes, including hair loss, depression, dry skin and hot flashes.
Now, as The Guardian reports, scientists have isolated a new postpartum change: after giving birth to their first child, women's voices really do tend to drop and become more monotonous. But the change is temporary, usually reverting back after about a year.
For the study, lead researcher Kasia Pisanski of the University of Sussex’s School of Psychology and her team tracked a group of 20 women who were pregnant and 20 age-matched women who had never given birth via 600 voice recordings over a 10-year period — five years before and five years after pregnancy for the mothers in the study. Included in the study group and control group were singers, actresses, journalists and celebrities.
After crunching the data, the team found that on average the voice pitch of new mothers dropped by more than 5 percent, or the equivalent of a half step on the piano. In addition, their highest pitch on average dropped by more than two steps. New mothers also had less variation in their pitch.
The work is published in the journal Evolution and Human Behavior.
“Our results demonstrate that pregnancy has a transient and perceptually salient masculinising effect on women’s voices,” the authors said in a statement.
This may be why, reports The Washington Post’s Allyson Chiu, the singer Adele had trouble hitting certain notes during a concert last year. She told the audience: “When I wrote that song, I was heavily pregnant” and that she experienced a lower, deeper voice.
The researchers, however, note that big voices changes happen postpartum. “Our results show that, despite some singers noticing that their voices get lower while pregnant, the big drop actually happens after they give birth,” Pisanski says in a news release.
Pisanski tells Chiu that anecdotal evidence of voice changes during and after pregnancy can be found in the past, though this is the first scientific study to quantify how giving birth affects a woman’s voice.
The reason for the lack of data comes down to a number of factors, Pisanski explains in an article for Quartz. "Studying long-term changes in the voice is no easy task. So previous studies were limited by comparing the voices of different groups of women (pregnant versus non-pregnant) or measuring the voice of only one woman across trimesters," she writes.
Speculating as to the reason behind the voice change postpartum, the teams says it could be an attempt to sound more authoritative as a new parent.
“Research has already shown that people with low-pitched voices are typically judged to be more competent, mature, and dominant, so it could be that women are modulating their own voices to sound more authoritative, faced with the new challenges of parenting,” Pisanski says in the release.
Next item on the agenda for the research team? Whether postpartum voice changes affect the listener’s perception of the new mother.