In a recent episode of the Happy Mum Happy Baby podcast, Keira Knightley revealed that her hair changed from straight to a curly texture during pregnancy. This unexpected transformation is not uncommon, as many women have shared similar experiences on social media, dubbing it 'Pregnancy Perms'. Knightley recounted how her hairdresser immediately recognized her pregnancy by the new texture of her hair. The underlying cause of these changes is attributed to hormonal fluctuations, particularly increased levels of estrogen and progesterone, which extend the hair's growth phase, resulting in thicker hair. While many women anticipate a fuller mane during pregnancy, they are often surprised when straight hair becomes curly or vice versa. After giving birth, however, the sudden drop in estrogen can lead to significant hair shedding, known as telogen effluvium. Though some women find their hair returns to its original state, others may notice lasting changes.