• Implantation is an early stage of pregnancy. It happens when a fertilized egg attaches to a woman's uterus. If it's a healthy pregnancy, the egg will develop into a fetus. 
• Implantation usually occurs 6 to 12 days after conception with symptoms lasting up to a week.
• One of the most apparent signs of implantation is light bleeding or spotting. Other symptoms include mild cramping and swollen or tender breasts. 
• You can ease any cramping with Tylenol. However, if cramping is severe schedule a visit with your doctor because it could be a sign of miscarriage. 
• This article was reviewed by Mahino A. Talib, MD, who is a clinical assistant professor with the Department of Obstetrics and Gynecology at NYU Langone.
• Visit Insider's homepage for more stories.

Your body undergoes a dramatic process from the time of conception to the first positive pregnancy test. One of the most significant steps is implantation.

Implantation is an early sign of pregnancy

After the fertilized egg travels down the fallopian tube toward the uterus, it divides into multiple cells and eventually becomes a growing cluster of about 100 cells called a blastocyst. 

You can think of this blastocyst as sort of like an orange because it has a thin outer layer and a larger inner group of cells. The inner group eventually becomes the embryo while the outer layer will form the part of the placenta that attaches to the lining of the uterus. When that attachment happens, that results in implantation.

Implantation occurs 6 to 12 days after conception

"Implantation occurs 6 to 12 days after conception or day 24 to 26 of your cycle," says Sherry Ross, an OB-GYN at Providence Saint John's Center. 

Since implantation happens so close to the start of your next period, any spotting you may experience is often mistaken for the beginning of your menstrual cycle. But instead of experiencing your usual PMS symptoms, your body will start producing the human chorionic gonadotropin, or hCG, hormone instead. HCG is what pregnancy tests detect to indicate you're pregnant. 

Implantation symptoms last up to a week 

One of the most apparent signs of implantation is light bleeding or spotting. An estimated 15 to 25% of women will experience bleeding in the first trimester.

But because the other symptoms that come with implantation are similar to your usual menstruation, it can be difficult to differentiate the two. Therefore, some women may not suspect pregnancy until they miss a period. 

Following is a list of the more common signs of implantation so that you know what to look for.

• Vaginal bleeding and spotting. "When the embryo implants itself in the uterine lining, there can be normal bleeding or spotting described as implantation bleeding," Ross says. The type of bleeding can be light red, brown, or pinkish. Implantation bleeding typically lasts 2 to 7 days. You can wear a panty liner to catch any spotting or discharge that may occur in the days after implantation.
• Mild uterine cramping. The hormonal shifts that happen from implantation may cause cramping or light pressure in your abdomen. This cramping is generally minor compared to the cramps you experience before and during your period. Cramping typically lasts for a few days. You can take Tylenol for it, but if the cramping becomes severe schedule a visit with a doctor, because it could be a sign of a miscarriage.
• Clear or white vaginal discharge. You may notice a difference between the clear and stretchy mucus during ovulation and the thicker, white or yellow discharge that can happen after implantation. Vaginal discharge is less common than spotting, Ross says, but if you do experience it, you can expect it to last only 1 or 2 days.
• Swollen or tender breasts. After implantation, rising hormone levels may cause your breasts to swell or feel tender. This often continues throughout your pregnancy. 

And if you're still not sure if these are symptoms of your regular menstrual cycle or of early pregnancy, take a pregnancy test to verify any suspicions. Just make sure to follow the directions for the test, and take the test at the right time, or you may get an inaccurate result.

Related stories about pregnancy:

• Your baby bump will pop out between weeks 12 to 16. Here's how to tell if you'll show early or late.
• How much weight you should gain during pregnancy, according to doctors
• Foods to avoid during pregnancy and how to still stay healthy
• How long it takes to recover from a C-section before you can drive a car, take a bath, and have sex
• Yes, Tylenol is safe for pregnancy. Here's the right dosage
• Doctors debunk the 25 biggest pregnancy myths

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