Androgenic and estrogenic indices in human newborns and infants: the MIREC-ID study
- DOI
- Language of the publication
- English
- Date
- 2019-03-11
- Type
- Article
- Author(s)
- Nguyen, T-V.
- Monnier, P.
- Muckle, G.
- Sathyanarayana, S.
- Ouellet, E.
- Velez, M. P.
- Dodds, L.
- Arbuckle, T. E.
- Publisher
- Cambridge University Press
Abstract
Prenatal sex steroid exposure plays an important role in determining child development. Yet, measurement of prenatal hormonal exposure has been limited by the paucity of newborn/infant data and the invasiveness of fetal hormonal sampling. Here we provide descriptive data from the MIREC-ID study (n=173 girls; 162 boys) on a range of minimally invasive physical indices thought to reflect prenatal exposure to androgens [anogenital distances (AGDs); penile length/width, scrotal/vulvar pigmentation], to estrogens [vaginal maturation index (VMI) – the degree of maturation of vaginal wall cells] or to both androgens/estrogens [2nd-to-4th digit ratio (2D:4D); areolar pigmentation, triceps/sub-scapular skinfold thickness, arm circumference]. VMI was found to be associated with triceps skinfold thickness (β=0.265, P=0.005), suggesting that this marker may be sensitive to estrogen levels produced by adipose tissue in girls. Both estrogenic and androgenic markers (VMI: β=0.338, P=0.031; 2D:4D – right: β=−0.207, P=0.040; left: β=−0.276, P=0.006; AGD-fourchette − β=0.253, P=0.036) were associated with areolar pigmentation in girls, supporting a role for the latter as an index of both androgen and estrogen exposure. We also found AGD-penis (distance from the anus to the penis) to be associated with scrotal pigmentation (β=0.290, P=0.048), as well as right arm circumference (β=0.462, P<0.0001), supporting the notion that these indices may be used together as markers of androgen exposure in boys. In sum, these findings support the use of several physical indices at birth to convey a more comprehensive picture of prenatal exposure to sex hormones.
Plain language summary
"Health Canada helps to protect the health of Canadians by assessing and managing the risks associated with exposure to endocrine disrupting chemicals. Androgen and estrogen hormones play an important role in the development of the child. However, it is difficult to measure hormone exposure during pregnancy. As some chemicals may affect the levels of these hormones, it would be useful to identify markers of changes in these hormones during pregnancy. In the MIREC-ID Study, potential markers of hormone exposure during pregnancy were measured in 173 female and 162 male infants. These markers included: (a) anogenital distance: distance between the anus and penis in boys, or between the anus and clitoris in girls; (b) length and width of penis; (c) coloring of the skin in the breast and genital areas; (d) examination of vaginal cells; (e) measurement of arm circumference; (f) skinfold thickness of the arm and back; and (g) ratio of the length of the index and ring fingers (2D:4D ratio). The study results showed that known markers of androgen exposure (i.e. anogenital distance (AGD)-clitoris and AGD-penis) were associated with coloring of the genital skin area, as well as right arm circumference. In girls, maturity of the vaginal cells was associated with skin color in the breast area and skinfold thickness of the right arm. These are likely good markers of estrogen exposure. In contrast, 2D:4D ratios, penile length/width and back skinfold thickness did not show any of the expected relationships with other potential measures of exposure to sex hormones. In summary, these results suggest that physical markers measured at birth may give a picture of hormonal exposure during pregnancy. However, these are preliminary results that must be verified by others before becoming accepted measures."
Subject
- Health,
- Health and safety