Lots of women who are trying to get pregnant wonder if there are any implantation symptoms they should be looking for. If you are really attuned to your body during the two week wait, is it possible to pick up on early signs of pregnancy—like twinges, cramps, or spotting—that might be related to a nascent embryo implanting in your womb?
Spoiler alert: not really (also, implantation bleeding is totally not a thing). Understanding the process of implantation will help explain why it’s impossible to know that implantation has successfully occurred until you get a positive pregnancy test. It will also help you understand why most early signs of pregnancy won’t happen until after your missed period.
What is implantation?
We usually think that pregnancy begins at conception—the moment that sperm enters the egg. But it makes more sense to consider the time when the fertilized egg successfully implants into the uterine wall as the true beginning of pregnancy.
Why? Well, implantation may be a bigger hurdle to clear than fertilization. Recent research shows that as many as two thirds of fertilized eggs fail to implant, indicating that embryos are likely predestined for survival or death before even the first cell division.
What is the process of implantation?
Let’s say you had sex in the days before ovulation occurred. When the egg was released, there were already sperm waiting in your fallopian tubes, and one of them managed to fertilize it. The fertilized egg begins rapidly dividing as it travels down the fallopian tubes toward the uterus.
When it enters the uterus, it begins the process of burrowing into the uterine wall, or implantation. There isn’t much you can do during implantation to impact the chances of pregnancy. If implantation does not occur, it probably means that the embryo had no chance of becoming a viable pregnancy.
The process of implantation is usually complete between 8 – 10 days after ovulation1. As soon as implantation is complete, the embryo starts producing hCG, which is the hormone that pregnancy tests detect. HCG sends a message to the corpus luteum to keep producing progesterone.
In a normal, non-pregnancy cycle, the corpus luteum is running out of progesterone at this point. Since progesterone is the hormone that provides structure to the uterine lining, when progesterone levels drop, your period starts. But the hCG produced by the newly implanted embryo “rescues” the corpus luteum, giving it a boost to help it keep producing progesterone. Your uterine lining stays nice and intact, and your period does not start.
Can you feel implantation?
Does the process of the embryo burrowing into the uterine wall produce any physical symptoms that you might notice? In a word, no. Even if you’re paying close attention to your body and notice little twinges, it’s highly unlikely that they are related to the implantation process.
The embryo is half the size of a dust mite, and you can’t feel anything happening in your body at that cellular level any more than you can feel your cells dividing or your hair growing.
When can you see signs of implantation on your chart?
Implantation almost always occurs between 8 – 10 days after ovulation. The embryo does not produce any hCG until implantation is complete. And even after implantation is complete, it can take a few days for hCG levels to build up high enough for a pregnancy test to detect.
This means that you should not expect to see any signs of pregnancy on your chart—or feel any symptoms of pregnancy in your body—until around 10 days past ovulation at the very earliest. Nothing that happens on your chart or in your body before that time has any significance for your chances of being pregnant.
If you’re not pregnant, the corpus luteum eventually runs out of progesterone, your levels drop, and your period starts. The decreased progesterone levels cause temperature and resting pulse rate to fall. For some women, the decrease in temperature and resting pulse rate falls the day of or the day before menstruation. If this is your typical pattern, then an elevated temperature and resting pulse rate could be early signs of pregnancy.
But many women have a delayed response to decreased progesterone levels, and don’t see their temperature and resting pulse rates start to fall until a few days into the next cycle. If that’s the case for you, you may not notice anything different on your pregnancy chart compared to a non-pregnancy chart.
Long story short, remember this: if you are pregnant enough for pregnancy signs and symptoms (in your body or on your chart), then you are pregnant enough to get a positive pregnancy test.
- http://www.nejm.org/doi/full/10.1056/NEJM199906103402304 ↩