I remember at college during our lectures being shown a chart which documented the factors which increased and slowed nail growth – all presumably based on some previous scientific observations or research. One of those listed as increasing the rate of growth was pregnancy. Indeed, the first papers on this subject have stated this fact (1, 2) whilst another suggested that nail growth declined in pregnant women over 30 (3). In 1966, a paper studying the nail growth patterns of 162 pregnant women (4) and comparing them with a control group of 45 student nurses concluded there to be an increased rate of growth, increasing particularly towards term (4).
Since then it’s been a bit quiet but in the last few years there have been a couple of studies published which have investigated or reported nail changes in pregnancy. Firstly, Erpolat and colleagues (5) studied 312 pregnant women, at all stages, to document nail changes associated with pregnancy. The group had an average age of 28 (18-40 range). The most commonly found nail change was white spots in the nail plate (leukonychia) in 24.4%, followed by ingrown toenails (9.0%) and splitting of the nails (onychoschizia) also affecting 9.0%. Leuconychia tended to occur earlier throughout the pregnancy with less common changes such as splitting, brittleness and onycholysis most frequently in the later stages (after 29 weeks). Interestingly, 6.71% of women also reported rapid nail growth but this was never formally measured.
In 2018, Ferhatoglu et al., undertook a prospective nail growth study to assess growth and thickness changes during pregnancy. Employing an accurate measurement instrument, they took serial measurements of length and nail thickness. This study aimed to address the deficiencies of previous studies by having no upper age limit of pregnancy and closely age-matching subjects with controls to ensure an accurate comparison. The findings suggested there is no increase in growth rate but a slight increase in nail thickness. The participant reported survey undertaken at the same time also suggests this as 80% of respondents felt their individual nail growth rates had not increased whilst pregnant.
They conclude that thickening of the nails might be due to increased levels of oestrogen and progesterone. Both have been shown to increase the thickness of the epidermis, subsequently they postulate this may have a similar effect on the nail produced.
References
1. Clark WE, Buxton lHD. Studies in nail growth. Br J Dermatol. 1938;50(5):221-35.
2. Halban J, Spitzer M. Über das gesteigerte wachstum der nagel in der schwangerschaft. Monatsschrift fur Geburtshulfe and Gynakologie. 1929;82:25.
3. Hillman RHB, 119–134. Fingernail growth in pregnancy: relations to some common parameters of the reproductive process. Hum Biol. 1960;32:119-34.
4. Hewitt D, Hillman RW. Relation between rate of nail growth in pregnant women and estimated previous general growth rate. Am J Clin Nutr. 1966;19(6):436-9.
5. Erpolat S, Eser A, Kaygusuz I, Balci H, Kosus A, Kosus N. Nail alterations during pregnancy: a clinical study. Int J Dermatol. 2016;55(10):1172-5.