When does implantation bleeding occur?

Implantation bleeding is a light spotting or short-term bleeding (lasting 1–3 days) caused by bursting of small blood vessels when the embryo attaches to the endometrium to continue its development. It occurs in approximately 3 out of 10 women, so its absence does not necessarily imply implantation failure.

When Does Implantation Bleeding Occur?

• In a natural cycle, implantation and, therefore, implantation bleeding usually occur between 6 and 10 days after ovulation.
• In IVF treatments, the timing of bleeding depends on the stage of the transferred embryo:
• If a 3-day-old embryo is transferred, bleeding may appear between 3 and 7 days after the transfer.
• If a 5-day-old blastocyst is transferred, bleeding may occur between 1 and 5 days after the transfer.

How Distinguish It from Other Types of Bleeding?

1. Bleeding due to the transfer procedure: It is common for patients to experience slight, dark-coloured spotting in the first few days after embryo transfer. This can result from cervical manipulation during the catheter insertion. Since this bleeding originates from the cervix and does not affect implantation, it does not require treatment.

1. Menstruation: The main difference is the intensity of bleeding, as implantation bleeding is much slighter than menstrual bleeding. Additionally, its duration is shorter.

1. Miscarriage: Like menstruation, miscarriage-related bleeding is usually heavier and comes with abdominal pain and other symptoms that may indicate pregnancy loss.

Implantation bleeding is a natural process that does not pose any risk to pregnancy development. However, if in doubt, it is advisable to consult a gynecologist, who can assess the cause of the bleeding and take appropriate action.