When the fertilized egg attaches itself to the uterine wall and begins to produce hCG it is called implantation.  This typically occurs between 6 and 8 days after ovulation.

The egg is fertilized in the outer part of the fallopian tube, generally within 12 hours of ovulation.  After it is fertilized, the egg travels down the fallopian tube.  The fertilized egg grows as it travels.  It doubles, the grows to four cells and then to eight cells as it enters the uterus. 

Implantation occurs in the upper third of the uterus.  Implantation sometimes can cause bleeding or minor spotting.  This is considered normal.  You may be able to use Basal body temperature (BBT) to determine when implantation occurs.

Basal Body Temperature refers to your body’s resting/waking temperature.  BBT is often used to chart fertility patters.  It can be used to confirm the passage of ovulation, but cannot predict when ovulation will occur.  It does this because the hormone progesterone, released in quantity after ovulation, causes the body’s internal temperature to rise slightly.

Some women may notice a second rise in temperature around the time of implantation.  This typically would occur around 6 days after ovulation.  This is referred to as a triphasic pattern.  In some rare cases, a woman may notice that her temp stays higher after ovulation, but will slightly dip around 6 days after ovulation;  this also can be an indication that implantation has occurred.

It is important to remember a few things about BBT.  First, temps need to be taken at the same time each morning.  Second, no warning of approaching ovulation, only confirmation when it has passed.  A minimum of 3 hours sleep is needed for an accurate temp.  Getting out of bed, any activity, drinking something, even a nightmare can alter your resting temps making them inaccurate or misleading.  Taking your temps for a minimum of a week is recommended, and longer may be better. There are certain advantages to charting the remainder of your cycle.

When does the fertilized egg implant?