The “two-week wait” between your carefully calculated ovulation and taking a pregnancy test can be very stressful, so you may be wondering: how does implantation occur? What conditions make implantation possible? And how might you know if it has occurred? Let’s take a look.

What is implantation?

Implantation is the attachment of a fertilized egg to the wall of the uterus and typically occurs between 6 and 12 days after ovulation, with most cases happening around day 9. At the point where the fertilized egg enters the uterus, it’s known as a blastocyst — a round collection of stem cells in a fluid with an outer layer that eventually forms the placenta. This outer layer is essential in this process because it is what adheres to and merges with the endometrium or uterine lining.

What can cause implantation to fail?

Unfortunately, various conditions can hamper the proper implantation of a blastocyst. In some cases, genetic disorders in the developing embryo disrupt the trypsin signal and cause a stress reaction that forces the uterus to reject the blastocyst. Immunological disorders may cause the mother’s body to attack the implanting embryo. Ultimately, this is a delicate process, and roughly half of all fertilized eggs fail to successfully implant.

Signs of Successful Implantation

If the embryo successfully implants, you can expect to experience a number of signs or symptoms. Unfortunately, the earliest signs of success can appear like the normal signs of a period: cramps, headaches, fatigue, and bloating. In 20% to 30% of women, implantation bleeding occurs, similar to what they experience during a period.

However, if it’s implantation and not  your period, additional symptoms will follow:

  • Your breasts may feel sore, tight, or tender.
  • If you continue tracking your basal body temperature after ovulation, you may notice that your average temperature has increased.
  • This rise in temperature, combined with fatigue and other symptoms, may make you think you have the flu.
  • Within a week, you may feel more frequent urges to urinate. This is because increased blood flow to the uterus has put pressure on your bladder.

Of course, the only way to tell if you have had a successful implantation is to take a pregnancy test. If you have any questions, schedule an appointment with your doctor.