Previous studies have shown that women with higher maternal tendencies are shorter and have lower testosterone levels than those with lower maternal tendencies. Here we report two studies that investigated the relationships between maternal tendencies and two further measures of physical masculinization/feminization; urinary estrogen metabolite (estrone-3-glucuronide: E1-3G) levels (Study 1) and rated facial femininity (Study 2). In Study 1, nulliparous women reported both their ideal number of children and ideal own age at first child and also provided urine samples. There was a significant positive correlation between measured late-follicular estrogen levels and reported ideal number of children. In Study 2, analyses of facial cues in two independent samples of women showed that the average facial characteristics of women who reported desiring many children were rated as more feminine than those desiring fewer children. Collectively, these results support the proposal that maternal tendencies are related to physical feminization and that this effect may, at least in part, reflect the influence of the hormone estrogen.
Law Smith, M. J., Deady, D. K., Moore, F. R., Jones, B. C., Cornwell, R. E., Stirrat, M., Lawson, J. F., Feinberg, D. R., & Perrett, D. I. (2012). Maternal tendencies in women are associated with estrogen levels and facial femininity. Hormones and Behavior, 61(1), 12-6. https://doi.org/10.1016/j.yhbeh.2011.09.005