The study: Does the contraceptive pill alter mate choice in humans?Alexandra Alvergne, Virpi Lummaa; October 06, 2009

As compared with normally cycling women, pill users show no or weaker preferences for facial and vocal masculinity. For instance, the preferred face shape is more masculine during the high conception-probability phase of the menstrual cycle in non-pill users, but pill users do not show similar preference.

These results suggest that the use of the pill is related to women favouring less symmetrical, masculine and MHC-dissimilar men, a preference attributed to the pill-induced changes in hormone levels simulating pregnancy….

Figure 1 shows how the pill tanks estrogen (blue line), which is essential for feminine characteristics. (a) normally cycling women and (b) pill users

Figure thumbnail gr1b2

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0:00 Hormonal birth control may be weakening society.
3:15 Women cycling without birth control were attracted to more masculine men.
5:35 Most birth control pills are synthetic progesterone, which has health impacts.
7:15 Follicle-stimulating hormone and luteinizing hormone (which benefits the Hypothalamic-Pituitary-Ovarian axis) are chronically suppressed with hormonal contraceptives.
7:40 It may take up to 90 or more days to normalize the HPA axis after stopping hormonal birth control.
8:45 Oral contraceptives may also contain estrogen, which suppresses the release follicle-stimulating hormone from the pituitary.
9:00 Increased risk of stroke and heart attack is linked with hormonal birth control.
9:40 Regulatory T cells are suppressed in women using hormonal birth control. [Autoimmune issues, allergies, thyroid, etc.]
11:45 Women on the pill are attracted to less masculine genetically similar individuals, potentially leading to infertility or health problems in children [as does the genetic similarity of relatives having offspring; could possibly result in gender disphoria].