Blastocyst

Pregnancy is one of the most thrilling and rewarding events in a woman’s life. This is an intricate process and your body undergoes several changes during this time. There are many myths and misconceptions about how fertilization takes place and what happens when an embryo is formed.

Pregnancy is generally divided into three trimesters but mother and fetus experience several changes almost every week throughout the process. After intercourse, sperm fertilizes the egg to produce a zygote. The cell division continues while the zygote travels down the fallopian tube and before entering the uterus it changes into a blastocyst.

Progesterone is a hormone that plays a role in many body functions including preparing the uterus for the implantation of a fertilized egg. When a woman has low levels of progesterone in her body, she may experience a shorter luteal phase, hormone imbalance (sometimes estrogen dominance), spotting before periods, early miscarriages, or infertility. If you suspect you have low progesterone, there are saliva hormone test kits that allow you to test your levels in the privacy of your home. There are several ways you may try to improve your progesterone levels and luckily, progesterone creams are common and available over-the-counter.

What is a Blastocyst?

Implantation is a very complex process as there are a number of things happening during the first week of pregnancy. Conception or fertilization occurs within hours or days of sexual intercourse. Conception is when sperm joins an egg in the fallopian tube. In case of assisted pregnancy, especially in-vitro fertilization, conception can occur in a lab. Following that cell division then results in the formation of a zygote.

In biology, the term “blast” refers to immature cells, as stem cells. A blastocyst forms when a zygote undergoes cell divisions in the fallopian tube. We can say a blastocyst is a muddle of cells that divides enough times to become an embryo. When a zygote becomes a blastocyst, it is ready for implantation in the endometrium. Normally, a blastocyst is formed at day 5 or 6 of fertilization and has 60 to 100 cells distributed in two layers.

What is a Blastocyst Stage?

The blastocyst stage of the fetus development is when your embryo grows to an immature cluster of 60 to 100 cells. A blastocyst is a hollow embryo nurtured by the uterine fluids and is free to move within the uterine cavity. At the blastocyst stage, the embryo enters the uterus and attaches itself to the uterine lining or endometrium. This process is known as implantation and it is a critical step in the development of the fetus.

Some women feel cramping and pain when the embryo attaches itself to the endometrium. However, the symptoms of early pregnancy can vary from one woman to the next. Women must be mindful of every change they’re feeling and discuss it in detail with their doctor to avoid any complications.

What Percentage of the Fertilized Eggs Makes it to the Blastocyst?

In many ways, growing embryos to the blastocyst stage weeds out less promising embryos before transfer because only the hardiest, strongest, most “developmentally competent” embryos can advance to the blastocyst stage. Unfortunately the lower quality embryos “arrest” or stop growing.

Some studies suggest that in cases of assisted reproductive technique, under a controlled environment and modern equipment, some laboratories may be able to convert around 60 percent of their fertilized eggs into blastocysts. The success rate may change for different laboratories. However, a success rate less than 40 percent is generally not considered good.

Is a Blastocyst a Baby?

A blastocyst isn’t “not a baby” in and of itself but it leads to the development of a fetus or a baby. When we look at the structure of a blastocyst, we see two layers of cells. The inner group of cells becomes an embryo in the later stages of pregnancy while the outer layer becomes its outer shell. The embryo will then develop into what we call a fetus or baby.

Is a Blastocyst a Good Embryo?

The question is not as perplexing as it appears because an embryo has to develop into a blastocyst before entering the uterus to ensure successful implantation. In assisted pregnancies, eggs are retrieved from a woman’s ovaries and joined with sperm in the lab. An embryo is formed which further develops into blastocyst after 5 to 6 days of cell division. Studies suggest that if your embryo enters the blastocyst stage, it has higher chances of implantation because it is a healthy embryo.

What Is The Success Rate Of Blastocyst Transfer?

It’s important to note that embryos that have grown to the blastocyst stage are far more likely to lead to a live birth than embryos that have arrived only at the cleavage stage. Below is an analysis of over 1,600 patients across 15 studies that demonstrate that transfers that use blastocysts are nearly 1.5x more likely to lead to a live birth than transfers that use cleavage-stage embryos. The net effect is that patients suffer fewer failed transfers when they have blastocysts transferred than when they have cleavage stage embryos transferred.

Blastocyst transfer is a procedure of assisted reproductive technique in which an early-stage embryo is developed artificially and transferred into the uterus during the IVF process. Blastocyst transfers are becoming popular because of their better success rates.

If you want to know more about IVF, read about what is IVF.

Moreover, blastocyst pregnancies are closer to the natural ones since blastocyst embryos are transferred to the uterus at almost the same time as it would for a natural pregnancy. Research suggests that for women under the age of 30 the blastocyst transfer has an almost 45 percent success rate.

What is the difference between Blastocyst and Embryo?

Embryonic development consists of different stages from the formation of the zygote to the development of the fetus. The blastocyst is produced when a zygote transforms due to cell division at the blastula stage whereas an embryo is formed when a blastocyst is implanted in the uterine lining.

The main difference between a blastocyst and an embryo is that a blastocyst is a thin-walled hollow structure from which the embryo arises whereas embryo is the early stages of the placental development from which the fetus arises. After the implantation of it in the uterine wall, the blastocyst is referred to as the embryo.

Is a Day 6 Blastocyst Ok?

Embryo development is yet another complex process due to the variety of changes in a short span of time. Usually it’s a good idea to grow an embryo up to day 5 because only competent embryos will reach the blastocyst stage. Blastocyst implantation normally occurs on day 6 to 10 after the egg retrieval. Studies reveal that blastocysts transferred on day 5 implant successfully at nearly twice the rate of those transferred at day 6. Some other studies suggest that day 6 transfer and hormone replacement therapy cycles may be linked with higher chances of miscarriage. Read on to learn how to help balance your hormones after a miscarriage.