Scalp Hair Diameter Increases During Pregnancy

The document summarizes a study that found an increase in scalp hair diameter during pregnancy. The study involved 12 pregnant women and 13 nonpregnant women, measuring the major-axis hair diameters of 15-20 fibers from each participant. The results indicated a significant increase in hair diameter for pregnant women (+0.58%/cm, r = 0.99, P < 0.0001) and a significant decrease for nonpregnant women (-0.66%/cm, r = -0.97, P < 0.0001). The study, which included a total of 25 participants, suggests that hair fibers not only become thicker during pregnancy but also transition orderly from small to medium to thick. It also points to the need for further research on the causes of these changes and their relation to post-partum hair shedding.