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Estrogen, progesterone, and human chorionic gonadotropin (hCG) levels throughout pregnancy. Estrogen, progesterone, and 17α-hydroxyprogesterone (17α-OHP) levels during pregnancy in women. [ 1 ] The dashed vertical lines separate the trimesters .
The x-axis shows the time of the menstrual cycle in days. The time scale starts with the beginning (or "onset") of (last) menstrual period (LMP), given as day number. Day number 1 corresponds to 0 to 0.99 days from LMP, and Day number 2 corresponds to 1.00 to 1.99 days from LMP and so forth.
Levels of progesterone and estrogen rise continually throughout pregnancy, suppressing the hypothalamic axis and subsequently the menstrual cycle. The progesterone is first produced by the corpus luteum and then by the placenta in the second trimester.
Menstrual cycle The menstrual cycle is a series of natural changes in hormone production and the structures of the uterus and ovaries of the female reproductive system that makes pregnancy possible. The ovarian cycle controls the production and release of eggs and the cyclic release of estrogen and progesterone. The uterine cycle governs the preparation and maintenance of the lining of the ...
Uterine contractions are muscle contractions of the uterine smooth muscle that can occur at various intensities in both the non-pregnant and pregnant uterine state. The non-pregnant uterus undergoes small, spontaneous contractions in addition to stronger, coordinated contractions during the menstrual cycle and orgasm.
FSH secretion begins to rise in the last few days of the previous menstrual cycle, [3] and is the highest and most important during the first week of the follicular phase [4] (Figure 1). The rise in FSH levels recruits five to seven tertiary-stage ovarian follicles (this stage follicle is also known as a Graafian follicle or antral follicle ...
During the reproductive years of human females, levels of estradiol are somewhat higher than that of estrone, except during the early follicular phase of the menstrual cycle; thus, estradiol may be considered the predominant estrogen during human female reproductive years in terms of absolute serum levels and estrogenic activity.
The luteal phase is characterized by changes to hormone levels, such as an increase in progesterone and estrogen levels, decrease in gonadotropins such as follicle-stimulating hormone (FSH) and luteinizing hormone (LH), changes to the endometrial lining to promote implantation of the fertilized egg, and development of the corpus luteum. In the ...