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Scalp hair diameter increases during pregnancy
1Department of Experimental Medicine and Cancer Research, Faculty of Medicine, Hebrew University of Jerusalem. nissimov@md.huji.ac.il
Clinical and Experimental Dermatology
|September 3, 2003
Summary
Pregnancy causes significant increases in hair shaft diameter, a reversal of the normal decrease towards the scalp. This study observed hair diameter changes in pregnant and nonpregnant women, revealing distinct patterns during gestation.
Area of Science:
- Dermatology
- Human Physiology
- Trichology
Background:
- Hair shaft diameter typically decreases towards the scalp in individual hair fibers.
- Previous research established this normal pattern of hair diameter reduction.
Purpose of the Study:
- To investigate changes in hair shaft major-axis diameter during pregnancy.
- To compare hair diameter changes in pregnant women with those in nonpregnant women.
Main Methods:
- Measured mean major-axis hair diameters of 15-20 fibers from 12 pregnant and 13 nonpregnant women.
- Sampled hair at 6-mm intervals from the scalp distally.
- Normalized hair diameters relative to conception or full-term pregnancy distance.
Main Results:
- Pregnant women exhibited significant increases in hair shaft diameter towards the scalp (0.58%/cm, P < 0.0001).
- Nonpregnant women showed a significant decrease in hair diameter towards the scalp (-0.66%/cm, P < 0.0001).
- Observed hair diameter increase in pregnancy begins at gestation's onset.
Conclusions:
- This study is the first to describe hair diameter increases during pregnancy.
- Pregnancy induces a significant, physiological change in hair shaft morphology.
- The findings contrast with the typical hair diameter decrease observed in nonpregnant individuals.