When Does Implantation Occur? Later Than You Might Think.
Medically reviewed by Samara Laxineta, RN on July 19, 2019
- Implantation usually occurs between 8 – 10 days after ovulation, with the most common day being 9 days after ovulation
- It’s rare for implantation to occur earlier than 8 days after ovulation
- The risk of miscarriage increases with late implantation
Implantation—the process of the egg implanting in the uterine wall—is the part of the conception process that feels like the true beginning of pregnancy. Even though your gynecologist considers the first day of your pregnancy the first day of your last menstrual period, your pregnancy hasn’t truly begun until the embryo has implanted in your uterine wall. But when, exactly, does this occur—and are there any symptoms of implantation?
There are no signs or symptoms of implantation you can observe in your own body. Women who track their cycles can often detect the date of ovulation, but there is no way to know for sure when implantation occurs for you.
There are studies that approximate when implantation occurs based on the first appearance of human chorionic gonadotropin (hCG) in a woman’s urine. Based on this method, one major study found that implantation occurs between 8 – 10 days after ovulation. In the study, 84 percent of women experienced implantation during this time period, with the most common day being 9 days after ovulation.
Understanding this helps explain when to take a pregnancy test, and how to avoid a false negative pregnancy test. It usually takes 1 – 2 days after implantation for hCG levels to be high enough to be detectable. This means that it’s unlikely that you would get a positive result earlier than 9 days after ovulation (and more likely at 12 days after ovulation).
How early can implantation happen?
The current research approximates that implantation can occur between 6 – 12 days after ovulation, and that implantation earlier than 8 days after ovulation is rare.
How late can implantation happen?
While implantation might happen later than 12 days after ovulation, the risk of early pregnancy loss increases the later implantation occurs. In one study, 13% of pregnancies that implanted at nine days after ovulation resulted in early loss. For pregnancies that implanted at 10 days after, that figure rises to 26%; for pregnancies 11 days after, it’s 52%; for pregnancies 12 or more days after, it’s 82%.
The reason for the increased miscarriage risk with later implantation may be due to the fact that unhealthy embryos develop and implant more slowly. In other words, it’s not that a healthy pregnancy failed because it implanted too late, but rather that late implantation is a sign that the pregnancy may have been doomed from the start.
What is the process of implantation?
To understand why it takes so long after ovulation for implantation to occur, let’s review the process of conception, day by day.
Five days before ovulation
About five days before ovulation marks the beginning of the maximum fertile window (the length of the fertile window may be shorter for some women, but is unlikely to be longer). Because of the lifespan of sperm, sex up to five days before ovulation can result in conception.
Two days before ovulation
Between 12 – 48 hours before ovulation on average, levels of luteinizing hormone will surge, which signals to the ovaries that it’s time to release an egg. You can use an ovulation test to detect the LH surge.
During ovulation, an egg is released from the ovary into the fallopian tube, where it begins its journey to the uterus. As soon as the egg is released, the clock starts ticking: a sperm must find and fertilize the egg within 24 hours in order for conception to occur. If a sperm manages to find and penetrate an egg during its journey down the fallopian tube, the egg changes instantaneously to prevent any other sperm from entering.
Three days after ovulation
During fertilization, the genetic material in the sperm and egg combine to create a new cell—called a blastocyst. The blastocyst begins to divide rapidly as it continues traveling down the fallopian tube towards the uterus. This journey takes about three days.
Seven days after ovulation
After the blastocyst reaches reaches the uterus, it can take another few days to implant itself in the uterine wall. Around 30 percent of women experience light bleeding around this time, but there is no evidence that implantation bleeding is an actual phenomenon. This bleeding, if it occurs, can last from several hours to a couple days. Most of the time, implantation occurs about nine days after ovulation, but it can occur as early as seven days or as late as 12 days after ovulation. Once implantation is complete, the cervix becomes closed with a mucus plug.
Nine days after ovulation
Twelve days after ovulation