Are you trying to conceive? Perhaps you’re wondering how long after sex implantation happens and when you might conceive. Does it happen straight away, or is there a time delay?
The answer to that question is not as straightforward as it might seem. It’s not an exact science that can say it’s two hours, two days, or two weeks.
There are several factors that come into play. In order to answer the question, we need to look at what happens to the sperm and the egg when they meet.
Also, we’ll look at what implantation is and how you will know if it’s happened.
What Is Conception?
Conception happens when egg meets sperm and the two join together to form what is called a zygote. This is the very beginning of a new life, called fertilization. The fertilized egg then makes its way to a woman’s womb, where it embeds itself in the uterine lining so it is ready to grow.
This is a basic outline of conception. We can already see three factors come into play:
- The journey of the sperm.
- The journey of the egg.
- Their joint travels to the womb or uterus, ready for implantation.
Let’s start by looking at the journey of the sperm.
The Quest of the Sperm
The life of the sperm begins in a male’s testicles which are found just below the penis. The scrotum, which houses the testicles, hangs outside a man’s body. This helps maintain an ideal temperature for sperm production, about 94 degrees Fahrenheit.
Whenever a man ejaculates, there can be anywhere between 20 million and 300 million sperm mixed in with semen. Men are continuously producing sperm and there is no limit to how many they will produce in a lifetime.
During sex, the sperm mixed with semen enters the vaginal canal through ejaculation. This can be a hostile environment for sperm and the semen is there to protect it. The sperm that swim the best (have the greatest motility) pass through the mucus in the cervix and enter the uterus.
Luckily for the sperm, when a woman ovulates, the cervical mucus becomes less hostile for them. It is less acidic which helps them survive. Once in the uterus, they then have to find their way to one of the fallopian tubes.
It seems the stereotype about men not following directions appears to apply to sperm too, as many will take a wrong turn and not reach their goal.
A Sperm Timeline
Once a sperm has penetrated an egg, the egg releases chemicals, repelling the other sperm. There is only one sperm for one egg. The rest of the many millions that were released are destroyed (1).
This video gives you a unique look at the journey the sperm take.
The Quest of the Egg
The journey of an egg begins even before a woman ovulates and ends when it reaches the uterus. Let’s look at the stages of its travels.
A female baby is born with all of the eggs she will ever have already in her ovaries – two egg-shaped organs situated just above the uterus and at the end of each fallopian tube.
Ovulation – the release of an egg – in most women occurs about 14 days into the menstrual cycle. This is, however, only an average and assumes a 28-day cycle. In reality, ovulation can occur anywhere between day 11 and day 21 of your cycle, day one being the day your period started.
The release of an egg is a carefully choreographed collaboration between five different hormones. Estrogen and progesterone are produced in the ovaries while Gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), and follicle stimulating hormone (FSH) are produced in the brain.
Between them, they signal the egg to leave the ovary and the uterus to prepare itself to receive a fertilized egg. Once released, the egg can only live for about 12 to 24 hours.
The finger-like ends of the fallopian tube sweep over the top of the ovary. On these are cilia, small hairlike projections that help move the egg through the tube to the uterus (2).
If the egg meets a viable sperm along the way then fertilization might happen. If not, then the egg — along with the uterus lining — is expelled. This is your monthly period.
This video details ovulation and release of an egg.
Sperm Meets Egg
The meeting of a sperm and egg is random as they each follow their own journey. If a sperm is waiting in the fallopian tube as the egg is released, fertilization can take place straight away. If not, sex within 12 to 24 hours of ovulation could lead to viable fertilization of the egg.
Following fertilization, the egg goes through a few changes. The initial stage is a single-cell, called a zygote. Over about five to six days, while traveling to the uterus, the egg keeps dividing.
Eventually, this multi-celled embryo becomes what is called a blastocyst and is ready to implant itself in the uterine wall (3).
The Process of Implantation
The lining of your uterus, signaled by hormones, prepares itself every month to receive a fertilized egg.
If a released egg does become fertilized, it burrows itself into the uterine lining and attaches itself in preparation to grow and become a baby. Implantation can take a couple of days to happen (4).
This video explains implantation.
How Long Do These Processes Take?
Time to do some math. We have mentioned some timescales for the journeys of the sperm and the egg, as well as the implantation process. Let’s add all these up and work out how long after sex is implantation.
We know that sperm can survive for five days, so even if you have sex before ovulation, fertilization is still possible. The egg can survive for 12 to 24 hours after release so this adds another day to the process. At the moment, we are at six days.
The fertilized egg can then take up to another six days to travel to the uterus — now we hit 12 days. It then takes a few more days for the egg to implant in the uterine lining. This takes us to about 14 days.
If you have sex at the time of ovulation and fertilization occurs, then implantation can happen as soon as seven days after sex.
How Will You Know If It Happens?
Some women might experience signs of implantation, while others don’t. Some of the signs are quite similar to premenstrual symptoms and can be confused with them.
These include light spotting or bleeding and stomach cramps, which aren’t as painful as those associated with PMS. You might experience headaches, nausea, backache, and breast tenderness. Mood swings are also possible.
You can read more about the symptoms of implantation in our article DPO Symptoms: Recognize The Signs You Could Be Pregnant.
What Happens After Implantation?
Once a fertilized egg has nestled into the uterus, it continues to grow. A hormone called human chorionic gonadotropin (hCG) is found in blood and urine.
This is what is detected on a pregnancy test. Depending on when you conceived, a positive test is possible as soon as three to four days after implantation. However, because this hormone increases as the baby grows, it’s best to wait until after day one of a missed period to do a test (6).
Find out more about pregnancy testing after implantation in our article When Can I Do a Pregnancy Test After Implantation?.
Timing Sex to Get Pregnant
The best time to have sex to get pregnant is during the five days leading up to ovulation and within a day of ovulation. However, as women’s menstrual cycles can vary, pinpointing this time can be difficult.
You essentially have a six-day window each month. If you have a regular 28-day cycle, this will be in the middle, between days 11 and 15. If your cycle is shorter or longer than 28 days, it will vary.
The best way to ensure a supply of sperm to fertilize your egg at ovulation is to have sex every two or three days. That way there will always be sperm ready and waiting for the egg to be released.
There are advantages to having sex every few days, apart from the obvious. One is that you won’t be tied to a calendar while waiting for ovulation. It takes the stress out of waiting to make that phone call for your partner to come home from work because “the time is right.”
The other advantage shown in recent years is that frequent sex can improve the quality and motility of the sperm (7).
Counting the Days
The answer to our initial question, how long after sex is implantation, has many variables. It depends on when you have sex in relation to when you ovulate. It also relies on the sperm and egg meeting and fertilizing.
The upshot is it can be anywhere between seven and 14 days. To ensure you don’t miss the window for ovulation and fertilization, have sex every two to three days.