When Does Implantation Occur in Pregnancy?

Implantation is one of the most dramatic biological events of your entire pregnancy — fertilization being the first. Although you may not even notice that implantation is happening, although some women experience period-like cramping and a little spotting. Either way, implantation silently marks the making of an embryo even before you know for sure that you're expecting.

What is implantation during pregnancy?

Implantation is a process that occurs after an embryo — i.e., a fertilized egg — travels down the fallopian tube and burrows deep into the lining of the uterus, where it will remain until delivery.

While many consider fertilization to be the start of pregnancy, successful implantation is another crucial hurdle. Once the embryo is implanted, it starts releasing hormones that prepare your body for baby, turning off your period, building up the placenta and possibly making you feel crampy and tired.

When does implantation occur?

Implantation occurs about eight to nine days after fertilization, though it can happen as early as six days and as late as 12 days after ovulation. 

What are the signs and symptoms of implantation?

The signs and symptoms of implantation are your body's way of welcoming you to pregnancy. While many women don't feel anything during the process, others report some symptoms, which can include:

Light bleeding

The difference between implantation symptoms and your period can be confusing, especially because in both instances, the blood is shed from the uterine lining. While most women don't experience implantation bleeding, some will, with approximately 15 to 25 percent of them experiencing light, spotty blood. This blood usually starts out pink and turns brown, and unlike your period, it won't flow or contain clots. It should stop within a day or two. 

Abdominal cramps

Many women don't have any symptoms of implantation, but the subsequent hormonal shifts can cause cramps. Implantation cramps should last only a day or so at most, and you'll probably notice them around the time your period is due.

While abdominal cramps are never fun, minor implantation cramps in early pregnancy are very common and shouldn't be as uncomfortable as those you might get before and during your period. Instead, you might feel a prickly or tingling sensation in your abdomen, as well as light pressure. Check in with your practitioner if you feel intense pain.

Other possible signs

Implantation isn't exactly painful, but very early pregnancy — no matter how joyful — can make you feel sick. While implantation itself is not to blame for the symptoms below, the cascade of hormonal changes helping your body launch a new life can leave you feeling temporarily weak and woozy.

Besides cramping and light bleeding, some women report:

• Swollen breasts
• Low energy
• Headaches

What is an implantation dip?

During the second half of the menstrual cycle, a woman's temperature starts to rise and goes up about 1 degree at the time of fertilization, where it remains elevated throughout her pregnancy. If your temperature drops back down, it could mean that your period is on its way, implantation didn't occur and you're not pregnant.

When should you take a pregnancy test?

Implantation is an important but easy-to-miss event. Because it can cause light spotting, some women mistake it for their menstrual cycle. If your period doesn't come and you are wondering whether or not you are actually pregnant, take a home pregnancy test or see your practitioner for confirmation. 

Although you'll probably be understandably anxious to take a test as soon as possible, your best bet is to wait to until about 19 days after fertilization. Human chorionic gonadotropin (hCG) production begins when the embryo implants in your uterus, and by 19 days after fertilization, hCG levels have built up enough to be detectable in your urine.