Implantation Bleeding: First Signs of Pregnancy
What is implantation?
To understand implantation bleeding, it is necessary to first understand the implantation process. After coming together with a sperm in the fallopian tubes, a newly-fertilised egg begins its developmental journey, growing into a blastocyst as it moves towards the uterus (womb). At this stage, the embryo adheres to the wall of the uterus – the endometrium – in a process called implantation. Implantation is necessary to provide an interface for the transfer of oxygen and nutrients from mother to embryo.
The endometrium, however, is not always ready to receive an embryo – it is only receptive to implantation for a few days each cycle – this period of endometrial receptivity is called the Window of Implantation (WoI). As many as 3 in 10 women have a WoI that is displaced, which can lead to failure if implantation is attempted during the ‘normal’ WoI timings – identifying your personal WoI can be critical in achieving implantation success.
Implantation is such a crucial stage in pregnancy development that it is used as an early indicator of success in both in vitro fertilisation (IVF) and natural conception.
The implantation process occurs in the first two weeks after fertilisation. As the embryo adheres to the wall of the uterus, it may burst small blood vessels within the endometrium – this may lead to a small amount of bleeding that is distinguishable from the bleeding associated with menstruation. Unlike menstruation, implantation bleeding:
- Is dark red or brown in colour, with a finer texture
- Is a mild spotting
- Does not usually last longer than a few hours
- May be accompanied by other signs of pregnancy
It is worth bearing in mind that there is not always bleeding during implantation – only 20% of pregnant women notice any bleeding during this stage of pregnancy. Implantation bleeding is absolutely normal and does not require medical attention, although if you believe it is necessary, you can consult your doctor.
Should I take a pregnancy test if I suspect implantation bleeding?
While seeing a sign of a potentially successful early-stage pregnancy can be exciting, you should resist the urge to take a pregnancy test immediately.
It is important to remember that most pregnancy tests check for the presence of the pregnancy hormone (beta hCG), which is not usually detected until at least one day after a missed period – taking a test at this stage will likely return a negative result.
Other early signs of pregnancy
Along with spotting, there are other potential indicators of implantation that may be present at this early stage:
- Implantation pain or cramping – abdominal pain, which is often mistaken for menstrual cramps – but the period does not arrive
- Increase in size and/or pain in the breasts
- Frequent urination – due to both pregnancy hormones and an increase in blood volume and uterus size
- Heightened sense of smell – may include a low tolerance to certain odours
- Sickness – the pregnancy hormones that lead to the well-known ‘morning sickness’ begin to accumulate early in pregnancy
Seed & Soil – Implantation success
Having success in the early stages of pregnancy is much like nurturing the first growth of a seedling– you must begin with a healthy seed and plant it in fertile soil. In humans, successful implantation requires both a healthy embryo and a receptive endometrium – these two factors must be perfectly synchronised in the 6-12 days following ovulation, or the embryo may fail to adhere to the lining of the uterus.
The health and potential of an embryo is something that can only be assessed during in vitro fertilisation (IVF) using techniques such as pre-implantation genetic testing for aneuploidies (PGT-A, formerly PGS).
The receptivity of the endometrium has been the subject of numerous studies in recent years. Independent analysis has demonstrated the effectiveness of the ERA test for determining an individual’s personal window of implantation.
Ensuring that you’re planting a healthy seed in fertile soil gives you the best chance at reaching this pregnancy milestone.