Common implantation symptoms include cramping and spotting, or very light bleeding, but those same signs can also be indicative of a normal menstrual cycle.
So how do you know when your symptoms indicate normal PMS or conception?
Dr. Bana Kashani, a reproductive endocrinology and infertility specialist in private practice in Orange County, California, tells TODAY.com implantation typically occurs between six to 12 days after ovulation, and once it does, pregnancy has begun.
"Implantation is when a fertilized egg, which has turned into a cluster of about 150-200 cells called a blastocyst, attaches to the uterine wall," Kashani says.
The California-based doctor says the blastocyst then attaches to the lining of the uterine wall called endometrium, which has undergone significant hormonal changes to become receptive to implantation of the blastocyst.
More information for parents trying to conceive:
What Are Implantation Symptoms?
Kashani tells TODAY.com that implantation symptoms can include: implantation bleeding, cramping, nausea, bloating, sore or tender breasts and mood swings.
"These symptoms can mimic PMS or the start of your menstrual cycle," she says.
Two symptoms commonly associated with implantation include bleeding and cramping.
Kashani says that implantation bleeding is actually more like spotting or very light bleeding that occurs prior to an expected period. The color can range from just pink or dark brown in color and is much less blood flow compared to a menstrual cycle.
"Implantation bleeding or spotting occurs only in a subset of patients who are pregnant and typically takes place around 10 to 14 days after conception," she says. "This occurs as a result of the blastocyst, or embryo, attaching to the uterine lining and then invading the endometrium to establish the pregnancy."
Implantation cramping is experienced when a blastocyst, or embryo, attaches itself to the lining of the uterus.
"This cramping can occur as the blastocyst invades the endometrium, or lining of the uterine wall, and starts to continue to grow," Kashani says. "Some people will experience implantation cramping, but you can still be pregnant and not have had implantation cramping."
Symptoms That Are Not Normal
Kashani tells TODAY.com that while spotting may be a sign of implantation, monthly spotting is a red flag.
“If you are experiencing monthly spotting after ovulation, even in months where you were not trying to get pregnant, please discuss this with your doctor," she ways. "Spotting after ovulation every month is not normal, and could indicate that there is some sort of pathology within the uterus, such as an endometrial polyp or fibroid, an infection or precancerous changes. Therefore, this should be addressed by an OB/GYN to help determine the cause."
I Have Implantation Symptoms — Now What?
Kashani tells TODAY.com that if you feel that you could be pregnant, then it is best to take a pregnancy test to know for sure.
"The earlier you identify if you are pregnant the better," she says. "My recommendation is to try First Response Early Result as it can detect pregnancy six days sooner than some of the other pregnancy tests.
The fertility specialist says that if you get a positive test, then you should contact your doctor to help you with the next steps.