05.01 Fertilization and Implantation

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Included In This Lesson

Study Tools



  1. Fertilization: when ovum and sperm unite in fallopian tube to form a zygote
  2. Implantation: when zygote travels from fallopian tube to uterus and implants itself into the thickened uterine wall

Nursing Points


  1. Fertilization
    1. Once one sperm successfully fertilizes the ovum, the outer membrane of the ovum polarizes and repels any other sperm from trying to fertilize
      1. So we don’t have too much genetic information
    2. Ovum carries half of the genetics from the mother and the sperm carries half of the father =1 set of chromosomes for the baby
      1. Each ovum and each sperm contains 23 chromosomes
      2. The union of egg and sperm become a zygote
  2. Implantation
    1. Considered the moment of true ‘conception’
    2. Zygote divides into a ball of cells→ blastocyst
    3. Blastocyst implants in the uterus
    4. If the blastocyst does not implant, it will not continue to grow and will be expelled vaginally
  3. Blastocyst
    1. Tells the corpus luteum to keep making progesterone → maintains the pregnancy→  thick vascular endometrial lining
    2. Supports the baby for the first 2-3 months until the placenta has been formed and takes over


  1. Implantation bleeding
    1. Some patients, not all
  2. Temperature elevation
    1. Increased estrogen

Therapeutic Management

  1. No real management necessary
    1. Pregnancy test once a missed period occurs

Nursing Concepts

  1. Reproduction
  2. Hormone Regulation
  3. Human Development

Patient Education

  1. Temperature tracking if trying to detect ovulation
  2. When to take a pregnancy test
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In this lesson I will explain the fertilization and implantation process.

Let’s look at fertilization compared to implantation. Fertilization is going to occur in the fallopian tube. Fertilization occurs when one sperm successfully fertilizes the ovum or egg. So when fertilization occurs the outer layer of the ovum will polarizes and repel any other sperm from trying to fertilize. This is important because we don’t want to have too much genetic information. One ovum has 23 chromosomes from the mother so that is half. One sperm will carry 23 other chromosomes, the other half. So when they unite we get our total of 46 chromosomes. If we had an extra sperm fertilize then we would have way too much genetic information and that wouldn’t be good or helpful. When the fertilization occurs it becomes a zygote. Now that fertilization has occurred let’s talk about implantation which is the next step. So the zygote is going to travel through the fallopian tube to get to the uterus. The uterus is the site of implantation. While the zygote travels there will be a lot of cell division occuring. When the zygote divides into a ball of cells it is now called a blastocyst. Remember “B” ball and “B” blastocyst. The blastocyst is what implants in the uterus. It will bury itself into the endometrial lining. When implantation happens this is true ‘conception’. The patient has conceived. If the blastocyst does not implant, it will not continue to grow and will be expelled vaginally. Conception has not occured. The blastocyst will tell the corpus luteum to keep making progesterone. The progesterone will maintain the pregnancy and cause the endometrial lining to thicken and support the pregnancy. So looking at this image we have the ovary here and the ovum or egg is released. Here come the sperm to fertilize. One of these sperm fertilize and now we have a zygote. That zygote is going to travel down the fallopian tube. While this is happening there is cell division occurring. At the end of cell division we have a ball of cells that is the blastocyst. The blastocyst will then implant into the uterus.

Let’s look at assessment. So there isn’t going to be a whole lot to assess on this patient at this time, but the patient might experience Implantation bleeding. This is usually very light spotting and happens because if you remember that blastocyst has to dig and bury itself into the uterine lining. This could cause a little spotting to occur. The other assessment piece will be for the patients that are doing the temperature tracking to detect their ovulation will see that there temperature stays elevated. This is because of the Increased estrogen.

There will be not be any real management necessary for this patient. She will have more management as the pregnancy progresses so for now it will just be a pregnancy test once the missed period occurs showing that fertilization and implantation has occurred.

There is also not going to be a lot of education at this point, but if the patient is using temperature tracking to detect ovulation and pregnancy. Refer to the lesson on family planning for more information on this. Other education might be when to take a pregnancy test. Pregnancy tests won’t detect a pregnancy usually until a missed period has occurred. This allows times of the hCG to rise.

Our nursing concepts are reproduction, hormone regulation, and human development. Reproduction has taken place with fertilization and implantation and now human development will occur. All of this will revolve around hormones.
Ok so now let’s look at our key points to review. Fertilization occurs in the fallopian tube and is when the sperm reaches the ovum. Remember 1 sperm to 1 ovum which will give us 46 chromosomes. It is now called a zygote. The zygote will have cell division and become a ball of cells. Remember this ball of cell is now called a blastocyst. This blastocyst will travel to the uterus for implantation into the uterus. She has now conceived!

Make sure you check out the resources attached to this lesson and review the route of the sperm to the egg and egg to the uterus. Now, go out and be your best selves today. And, as always, happy nursing.

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