Endocrinology

Step 1: hCG (Human Chorionic Gonadotropin).
Source: Secreted by the placenta.
Function: hCG stimulates the corpus luteum to continue producing progesterone, which is necessary to maintain the pregnancy.
Step 2: FSH (Follicle Stimulating Hormone).
Source: Secreted by the anterior pituitary.
Function: FSH stimulates the growth and maturation of ovarian follicles and the secretion of estrogen.
Step 3: LH (Luteinizing Hormone).
Source: Secreted by the anterior pituitary.
Function: LH triggers ovulation and the formation of the corpus luteum, which secretes progesterone.
Step 4: Relaxin.
Source: Secreted by the ovaries and placenta.
Function: Relaxin helps relax the uterine muscles and soften the cervix to facilitate childbirth.

Step 1: Sequence of Hormone Secretion.
The correct sequence of hormone secretion in a pregnant woman is:
1. hCG (Human Chorionic Gonadotropin)
2. FSH (Follicle Stimulating Hormone)
3. LH (Luteinizing Hormone)
4. Relaxin
Step 2: Hormonal Function.
hCG is secreted early in pregnancy to maintain the corpus luteum and progesterone production. FSH and LH are involved in the early menstrual cycle and preparation for ovulation. Relaxin is secreted later and helps with the relaxation of the uterine muscles and cervix.