During the second and third trimesters, which structure takes over estrogen and progesterone production?

During the second and third trimesters, which structure takes over estrogen and progesterone production?

• A. Adrenal gland
• B. Hypothalamus
• C. Corpus luteum
• D. Placenta

Answer: (D)

A shift occurs in pregnancy where the placenta becomes the main producer of both estrogen and progesterone after the early weeks. This luteoplacental shift means the placenta provides the hormones needed to maintain the uterine lining, support fetal growth, and prepare the body for birth and lactation, while the corpus luteum's role diminishes. In the second and third trimesters, placental production of progesterone keeps the uterus relaxed to prevent contractions and helps maintain the endometrium, and placental estrogen (primarily estriol) promotes uterine blood flow and breast development. The adrenal gland and hypothalamus don’t supply these steroid hormones in the quantities needed for sustaining pregnancy at this stage, and the corpus luteum, although crucial early on, is no longer the dominant source by the second trimester.

A shift occurs in pregnancy where the placenta becomes the main producer of both estrogen and progesterone after the early weeks. This luteoplacental shift means the placenta provides the hormones needed to maintain the uterine lining, support fetal growth, and prepare the body for birth and lactation, while the corpus luteum's role diminishes.

In the second and third trimesters, placental production of progesterone keeps the uterus relaxed to prevent contractions and helps maintain the endometrium, and placental estrogen (primarily estriol) promotes uterine blood flow and breast development. The adrenal gland and hypothalamus don’t supply these steroid hormones in the quantities needed for sustaining pregnancy at this stage, and the corpus luteum, although crucial early on, is no longer the dominant source by the second trimester.