This is where things start getting serious. The hormones have done their job, eggs are collected, sperm is ready, and the embryologist is about to take over. Step 3 of the IVF journey begins here: fertilisation and embryo development in IVF.
At Family Fertility & IVF Center Lahore, this step takes place under the supervision of Dr. Sophia Umair Bajwa, one of the most trusted names in fertility care. The goal is simple: help the sperm meet the egg in the most accurate, controlled, and effective way possible so fertilisation can happen smoothly.
How ICSI Works
After egg pickup, the embryologist checks which eggs are mature. Only mature eggs can be fertilised. Each mature egg is placed under a microscope. Then, one strong sperm is carefully selected and injected into it.
It sounds tiny, but this one step changes everything. If fertilisation happens, that egg becomes the start of an embryo. If not, it stops there. That’s why this stage needs a perfect setup, experienced embryologists, and high-quality lab conditions.
Day 1: Fertilisation Check
The next day after ICSI, the embryologist checks each egg. This is called Day 1, or the pronuclear stage.
Two small circles inside the egg mean success: one from the sperm and one from the egg. When both are visible, fertilisation has worked. That’s the first good sign that the embryo is forming.
This is where embryo development in IVF officially begins. Each fertilised egg is then placed safely in the incubator to grow further.
Day 3: Cell Division Stage
By Day 3, the fertilised egg has started dividing into multiple cells. This is known as the cleavage stage.
A healthy embryo at this point usually has between six and eight cells. The embryologist checks how the cells look: are they even, are they dividing well, and is there too much fragmentation. These details matter because they tell how strong the embryo is.
Some couples might have their embryo transferred at this stage. Others may wait until Day 5 for it to reach the next level of growth. The choice between IVF embryo transfer Day 3 vs Day 5 depends on how well the embryos are developing and what the doctor recommends.
Day 5: Blastocyst Stage
By Day 5, the strong embryos reach what’s called the blastocyst stage. This is a big milestone in the stages of embryo development IVF process.
A blastocyst has two main parts:
- The inner cell mass, which develops into the baby.
- The outer layer, which later becomes the placenta.
Embryos that reach this point are more likely to lead to a successful pregnancy. The blastocyst development stages help the embryologist select the best-quality embryos for transfer or freezing.
Embryo Freezing
Sometimes, the doctor may decide to freeze the embryos instead of transferring them right away. This can happen for many reasons, maybe the uterus lining isn’t ready or maybe the couple wants to delay the transfer.
Freezing, also known as cryopreservation, keeps embryos safe for years. When the time is right, they can be thawed and transferred without losing their quality. In fact, many couples have successful pregnancies using frozen embryos.
At Family Fertility & IVF Center Lahore, the freezing process is done with advanced technology to maintain embryo quality at every stage.
Embryo Transfer
After the embryos are ready, the next step is embryo transfer. This is where the best embryo, or sometimes two, are placed into the uterus.
The procedure is simple, doesn’t need anesthesia, and takes only a few minutes. After that, it’s all about waiting for the embryo to attach and start growing naturally.
Whether the transfer happens on Day 3 or Day 5 depends on each case. The 3 day vs 5 day embryo IVF discussion mostly comes down to embryo quality and how the body is responding.
What Happens in the Lab Each Day
Here’s a quick look at the embryo development day by day IVF process:
- Day 0: The ICSI procedure is done.
- Day 1: Fertilisation confirmed (pronuclear stage).
- Day 2: Embryos start dividing into 2–4 cells.
- Day 3: Cleavage stage (6–8 cells).
- Day 4: Morula stage (cells compact and prepare to form blastocyst).
- Day 5: Blastocyst stage (ready for transfer or freezing).
Each of these stages in the growth process from zygote to embryo is carefully monitored. The lab team checks every detail: cell growth, symmetry, and strength to ensure only the healthiest embryos continue developing.
What Patients Should Know
This step of IVF can feel like a waiting game. The couple has already gone through hormonal injections and egg retrieval, and now everything depends on how the embryos grow in the lab. It’s a mix of hope, anxiety, and patience.
A few common questions that always come up:
Do all eggs fertilise after ICSI?
No. Only mature and healthy eggs fertilise successfully.
What if embryos stop growing?
Sometimes, they stop dividing. The doctor reviews the case and adjusts the treatment for the next cycle.
Are Day 5 transfers always better than Day 3?
Not always. Both can lead to pregnancy depending on the patient and embryo quality.
Are frozen embryos as effective as fresh ones?
Yes. With advanced freezing methods, frozen embryos work just as well.
How long can embryos stay frozen?
For many years. Couples often come back later for another transfer using frozen embryos.
Why This Step Is So Important
The ICSI and embryo development phase decides how strong the embryos will be for transfer. Without successful fertilisation, IVF cannot continue. Without proper monitoring, even good embryos might not survive.
That’s why this step requires skill, advanced equipment, and experienced embryologists. At Family Fertility & IVF Center Lahore, every stage is managed carefully, from fertilisation to blastocyst development IVF, so embryos have the best chance to grow healthy.
Dr. Sophia Umair Bajwa personally oversees the lab protocols and embryology procedures to ensure accuracy and consistency in every cycle.
The End of Step 3, The Start of New Possibilities
Step 3 is the real turning point in the IVF journey. Once fertilisation is confirmed, the focus shifts to how the embryos grow, divide, and reach the blastocyst stage. Those few days in the lab decide what happens next.
At Family Fertility & IVF Center Lahore, every step in this process happens under strict lab supervision and the expertise of Dr. Sophia Umair Bajwa. The embryos are observed, documented, and handled with precision to make sure each one gets the best chance to develop normally.
Couples waiting through this phase often call it the toughest part, because all the work has been done, and now it’s up to nature and science to do the rest. But with the right lab setup, skilled embryologists, and transparent progress updates, that wait becomes easier to handle.
For clear, easy-to-understand explanations about how IVF labs work and what each stage means, visit the Dr. Sophia Umair Bajwa YouTube channel. And when it comes to trusted IVF care, Family Fertility & IVF Center Lahore continues to stand out for its technology, transparency, and results.
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