Whether natural conception or through IVF, fertilisation is just the beginning of a complex and incredible process. Understanding what happens next can help you support your partner during this critical stage.
Essential Info
• After fertilisation, a fertilised egg (zygote) begins a journey of rapid development.
• Implantation is the stage where pregnancy begins, as the embryo attaches to the uterus lining.
• IVF embryos are carefully transferred into the uterus, where they follow the same path as naturally conceived ones.
The Journey After Fertilisation
Once fertilisation occurs, the fertilised egg begins its journey to the uterus. In natural conception, this process takes place in the fallopian tube, while in IVF, fertilisation happens in a lab.
After fertilisation:
• 12 hours post-conception: The egg, now a zygote, remains a single cell.
• 30–45 hours: The zygote divides into two, then four cells.
• 3 days: The zygote becomes a morula, a 16-cell structure.
• 5–6 days: It transforms into a blastocyst, a hollow ball of hundreds of cells.
In natural conception, tiny hair-like structures (cilia) guide the blastocyst through the fallopian tube to the uterus. In IVF, the blastocyst is carefully transferred into the uterus by a specialist.
What is Implantation?
Implantation is when the fertilised egg attaches to the uterine wall (endometrium), officially marking the start of pregnancy. After transfer during IVF, the embryo must successfully attach itself in the same way.
During implantation:
• The uterus releases enzymes that help the blastocyst burrow into the lining.
• Hormones such as oestrogen, progesterone, and human chorionic gonadotropin (HCG) are released to support pregnancy.
Implantation typically occurs 6–12 days after fertilisation, whether natural or through IVF.
What Symptoms Might Your Partner Experience?
Not every woman experiences symptoms during implantation, but for those who do, these are common:
• Light bleeding: Spotting that is lighter than a period, often pink or brown, and lasting 1–2 days.
• Cramping: A mild or prickly sensation in the abdomen.
• Fatigue: Hormonal changes can make her feel unusually tired.
• Breast tenderness: Swelling or soreness due to rising hormone levels.
Post-Embryo Transfer (IVF):
• Rest and hydration are often recommended after the transfer, but excessive bed rest is unnecessary.
• Symptoms of implantation may be similar to natural conception, such as spotting or cramping.
• A pregnancy test is typically scheduled 10–14 days after the embryo transfer to confirm success.
What If Implantation Doesn’t Happen?
In both natural conception and IVF, fertilisation doesn’t always lead to pregnancy. Common reasons for implantation failure include:
• Uterine abnormalities (e.g., fibroids or adhesions).
• Hormonal imbalances or genetic issues with the embryo.
• Infections or immune-related factors.
For IVF patients, recurrent implantation failure (RIF) may occur after multiple failed cycles. In these cases, specialists may recommend additional tests or adjustments to treatment protocols, such as improving the uterine environment or enhancing embryo quality.
How You Can Support Your Partner
• Be Informed: Learn about the process to better empathise with her experience.
• Offer Practical Help: Take over daily tasks if she feels fatigued or unwell.
• Provide Emotional Support: IVF can be emotionally draining. Listen and validate her feelings without judgment.
• Stay Patient: Success may take time, and setbacks are a normal part of the journey.
Conclusion
Fertilisation and implantation are critical stages in achieving a pregnancy, whether naturally or through IVF. Your understanding of the process can help you be a stronger partner during this time. For trusted advice and resources, visit the NHS or HFEA.