Final answer:
The false statement about estrogens is that they maintain pregnancy and breast development for lactation; this role is primarily attributed to progesterone, not estrogens.
Step-by-step explanation:
The statement among the options regarding estrogens that is NOT true is: d. Estrogens maintain pregnancy and breast development for lactation. While estrogens play a critical role in the development and maintenance of the female reproductive system and secondary sexual characteristics, it is primarily progesterone that maintains pregnancy after the first trimester and facilitates breast development for lactation. Estrogens do contribute to many physiological processes, including the promotion of development and maintenance of female reproductive structures, lowering blood cholesterol, and moderation of hormone levels which involve inhibition of GnRH and secretion of FSH and LH. However, attributing the maintenance of pregnancy and breast development for lactation predominantly to estrogens would be inaccurate.
Estrogens are a class of hormones including estradiol, estriol, and estrone, produced by the ovaries. They are imperative for the development of secondary sexual characteristics, regulation of the menstrual cycle, and endometrial regrowth. Estrogens have been known to increase levels of both HDL and LDL, and thus, play a role in reducing the risk of atherosclerosis. During pregnancy, estrogens alongside progesterone are secreted by the placenta and contribute to several processes that ensure fetal viability and tissue growth.
The role in hormone regulation for the female reproductive cycle is a complex interplay between the hypothalamus, pituitary, and ovaries, with hormones such as FSH, LH, GnRH, estrogen, and progesterone orchestrating the process. Importantly, while estrogen is necessary for the appearance of secondary sexual characteristics at puberty and for the maturation and maintenance of reproductive organs, progesterone operates alongside estrogen to regulate menstrual cycle changes in the endometrium and is key for maintaining pregnancy.