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Module 06

Implantation

How the blastocyst finds a receptive lining, attaches and burrows in, why hCG appears when it does, and what happens when an early pregnancy does not continue.

  • 4lessons
  • 18 minreading
  • 6quiz questions
Start the module Take the quiz

The lessons and the quiz in this module are part of the Fertility with Kara Package. Module 1 is free to read.

Your way through Module 06

  1. Lesson 6.1 · 5 min A lining ready to receive How the lining of the uterus grows each month, how progesterone changes it, and why it is open to an embryo for only a few days.
  2. Lesson 6.2 · 4 min How the embryo attaches and burrows in The three steps of implantation, from a loose first touch to an embryo buried in the lining and tapping into its mother's blood supply.
  3. Lesson 6.3 · 5 min hCG and when a pregnancy test turns positive What hCG does, why it cannot appear before implantation, and why a test on the day your period is due can still be too early.
  4. Lesson 6.4 · 4 min When an early pregnancy does not continue Biochemical pregnancy, early miscarriage and ectopic pregnancy explained gently, with the warning signs that need urgent care.
  5. Quiz6 questions · 5 to passNot taken BadgeModule 06Earned with the quiz

Learning aims

By the end of this module you will be able to:

  • Describe how oestrogen and progesterone prepare the lining of the uterus, and what the window of implantation is.
  • Explain the three steps of implantation: apposition, adhesion and invasion.
  • Explain where hCG comes from and why a pregnancy test cannot be positive before implantation.
  • Recognise the warning signs of an ectopic pregnancy and know when to seek urgent care.
  • Describe a biochemical pregnancy and early miscarriage in plain, accurate terms.
  • Ask your clinic how your lining is prepared and how transfer and testing are timed.

The module in brief

The module in brief
  • Oestrogen rebuilds the lining of the uterus after each period, and progesterone from the corpus luteum then makes it receptive.
  • The lining accepts an embryo for only about 3 to 6 days in each cycle, the window of implantation.
  • Implantation has three steps: loose contact, firm attachment, and invasion by the syncytiotrophoblast, which buries the embryo in the lining by about day 12 after fertilisation.
  • hCG is made by the implanting embryo, first appears 6 to 12 days after ovulation, and keeps progesterone and the lining in place.
  • About 1 in 10 pregnancies has not yet implanted on the day a period is due, so an early negative test is not the final answer.
  • Very early losses and miscarriages are common, often caused by a chromosome difference in the embryo, and very rarely anyone's fault.
  • Pain or bleeding with a positive pregnancy test needs prompt care, because it can be a sign of an ectopic pregnancy.
A note from Kara

Thank you for choosing to learn with me

I know you had many places to look for answers, and you chose this course. Thank you. It means a lot to me that you trust me with something this close to your heart.

Every lesson here is something I wish every couple could hear before they sit down with their clinic: how a life begins, what happens in the lab, and what the words on your report mean. Take it slowly. Short lessons, one at a time, are the way the science sinks in.

If a lesson raises a question about your own body or your own embryos, write it down and take it to your healthcare professional. That is exactly what this course is for.

Warmly, Kara

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