Snapshot A 27-year-old woman presents to her primary care physician due to missed menses. She reports to having a 28-day menstrual cycle with minimal variability, and her last menstrual period was 7 weeks ago. She reports morning sickness and is currently sexually active with one man and use condoms intermittently. Physical examination is unremarkable. A urine β-hCG test is positive. (Pregnancy) Introduction Estrogen source ovaries (17β-estradiol), placenta (estriol), and adipose (estrone) ovarian synthesis theca cells produce androgens secondary to luteinizing hormone (LH) stimulation androgens diffuse to adjacent granulosa cells granulosa cells, under follicle-stimulating hormone (FSH) stimulation, leads to ↑ aromatase activity that results in ↑ conversion of androgens to estrogens (17β-estradiol) function matures and maintains the fallopian tubes, uterus, cervix, and vagina develops secondary sex characteristics breast development maintains pregnancy also decreases uterine threshold to contractile stimuli during pregnancy increases mitotic activity of the endometrium negative and positive feedback effects on FSH and LH secretion Progesterone source corpus luteum, placenta, and adrenal cortex in women function maintains pregnancy increases uterine threshold to contractile stimuli during pregnancy breast development negative feedback on FSH and LH secretion (in luteal phase) uterine secretory activity maintenance in the luteal phase Oogenesis during fetal life 1° oocytes begin meiosis I meiosis I is completed prior to ovulation the oocytes are arrested in prophase I until ovulation occurs oocytes are arrested in metaphase II until the oocyte becomes fertilized Menstrual Cycle Follicular phase (days 1-14) a primordial follicle is formed upregulation of LH and FSH receptors on theca and granulosa cells ↑ estrogen results in uterine proliferation negative feedback on anterior pituitary leading to ↓ LH and FSH levels ↓ progesterone levels Ovulation (day 14) ovulation = menses - 14 days secondary to estrogen-induced LH surge cervical mucous is thin, clear, and profuse secondary to ↑ estrogen levels ferning on wet mount due to electrolyte ↑ content anovulation can occur during the first few menstrual cycles due to an immature hypothalamic-pituitary-gonadal axis Luteal phase (days 14-28) development of the corpus luteum which results in estrogen and progesterone synthesis endometrium has ↑ vascularity and secretory activity ↑ basal body temperature due to progesterone's effect on the hypothalamus no fertilization leads to regression of the corpus luteum leading to an abrupt ↓ of estradiol and progesterone Menses (days 0-4) ↓ estradiol and progesterone leads to endometrial sloughing Pathology neonates may experience "menses" secondary to rapid withdrawal of maternal hormones no diagnostic workup or treatment required amenorrhea (primary and secondary) dysmenorrhea abnormal uterine bleeding Pregnancy Fertilization human chorionic gonadotropin (hCG) rescues the corpus luteum from regression which results in continued progesterone secretion Human placental lactogen (HPL) ↑ insulin resistance which results in ↑ glucose and amino acids to the fetus Physiology cardiovascular systolic and diastolic blood pressures (BP) decline there is an ↑ cardiac output and heart rate diastolic murmurs are never normal in pregnancy hematologic dilutional effect on hemoglobin (physiologic anemia) due to increased plasma volume hypercoagulable state pulmonary ↑ tidal volume and minute ventilation that results in a respiratory alkalosis kidneys ↑ bicarbonate loss to compensate