Summary
hCG maintains the corpus luteum early on, then the placenta produces progesterone and oestrogen.
In depth
Placenta produces progesterone (maintains pregnancy), oestrogen (growth of uterus and breasts), hCG (early), human placental lactogen (maternal metabolism) and relaxin. High progesterone suppresses uterine contractions until late pregnancy.
Hormone levels rise massively in pregnancy. Placental hormones also adjust maternal metabolism. After birth they fall sharply.
Remember: progesterone prevents contractions until near term.
Human chorionic gonadotropin (hCG) is made by the trophoblast and then placenta shortly after implantation. It acts like LH, keeping the corpus luteum making progesterone and oestrogen for the first 8 to 10 weeks. It is the hormone detected in pregnancy tests in urine or blood.
After about week 10, the placenta takes over production of progesterone (which maintains the endometrium and relaxes the uterus) and oestrogen (which stimulates uterine and breast growth). Human placental lactogen alters maternal metabolism for the fetus, relaxin softens ligaments, and prolactin prepares the breasts. Hormone levels fall after birth.
Example: morning sickness coincides with peak hCG.
Key idea: the placenta is a temporary endocrine gland.
Frequently asked questions
What is Pregnancy Hormones?
hCG maintains the corpus luteum early on, then the placenta produces progesterone and oestrogen.
Which area of biology covers Pregnancy Hormones, and how advanced is it?
Pregnancy Hormones is one of the 54 topics in Reproduction & Endocrinology. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Hormonal Control of the Menstrual Cycle, Pregnancy, Implantation.
Can you give an example of Pregnancy Hormones?
HCG levels double every 48 to 72 hours early on.
What should I learn before Pregnancy Hormones?
Work through the Beginner topics in Reproduction & Endocrinology first, such as Reproduction, Asexual Reproduction, Sexual Reproduction, then return to Pregnancy Hormones. Intermediate topics assume the Beginner vocabulary.
What topics are related to Pregnancy Hormones?
The closest topics to Pregnancy Hormones are Hormonal Control of the Menstrual Cycle, Pregnancy, Implantation, Menstrual Cycle. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Pregnancy Hormones?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Pregnancy Hormones. To practise the whole of Reproduction & Endocrinology, use the Reproduction & Endocrinology quiz.
How is Pregnancy Hormones different from Hormonal Control of the Menstrual Cycle?
Pregnancy Hormones: hCG maintains the corpus luteum early on, then the placenta produces progesterone and oestrogen. Hormonal Control of the Menstrual Cycle: FSH, LH, oestrogen and progesterone interact in feedback loops to time ovulation and menstruation. Read both side by side and note what each one explains.
How should I study Pregnancy Hormones step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Hormonal Control of the Menstrual Cycle and explain the difference aloud. Finally, take the Reproduction & Endocrinology quiz and come back to this page for any question you miss.