What Is Conception?

Couple in bed embracing

Pekic / Getty Images


Conception is the successful joining of an egg and sperm. This process can occur in the hours to days after having sexual intercourse.

During sex, a male ejaculates and releases semen into the vagina. Within the semen are sperm that will fight to travel out of the semen and into a woman’s cervical mucus.

Some sperm make it, but many will die before reaching the cervical mucus. From here, the strongest sperm will travel to the fallopian tubes and wait for an egg to fertilize. If the two meet up, conception can occur.

Even though the sperm has now fertilized an egg, there are still a few more steps that need to take place before pregnancy is successful. 

Conception and Your Menstrual Cycle

Your menstrual cycle is calculated from the first day of menstrual bleeding of one period to the first day of menstrual bleeding of your next period.

In general, doctors refer to a menstrual cycle as 28 days in length. That said, many women experience shorter or longer cycles. This can impact when ovulation occurs, and consequently when you conceive. 

Day one of your cycle is considered the first day of your period. Around the midpoint of your cycle, an ovary releases an egg by a process called ovulation. You will usually only release one egg at a time during ovulation. In a 28-day cycle, ovulation occurs around day 14, which is about 14 days before the start of your next period.

If you release an egg during ovulation, it travels down the fallopian tube toward the uterus. An egg can survive for about 24 hours after ovulation. After that, it loses the ability to be fertilized by a sperm. Because fertilization occurs in the fallopian tube, an unfertilized egg disintegrates before ever reaching the uterus.

When Does Conception Happen?

Conception can happen shortly after sex or several days later. Although an egg has a short life span, semen can live up to five days in the female reproductive tract.

This means conception can happen in as little as a few hours and up to five days after having sex.

There are two ways conception can take place. Both require an egg and sperm to meet, but one can happen sooner than the other. 

  1. You have sex during the 24-hour period you are ovulating: If you are ovulating and release an egg, the egg will travel to the fallopian tube where it will remain for up to 24 hours. If you have sex during this time, and your partner ejaculates, a sperm can make its way up to the fallopian tube and meet up with the egg. If the sperm fertilizes the egg, conception takes place. 
  2. You have sex in the days leading up to or right after ovulation: If you have sex, but you are not ovulating, conception can still take place. For example, if you have sex on day 13 of your menstrual cycle, the sperm cells swim out from the semen, up through the cervical opening into the uterus, and finally land in the fallopian tubes. This is where the sperm stays until it either meets up with an egg or dies. You ovulate and release an egg on day 14. The sperm could still be alive and waiting to meet up with the egg. If this happens, conception occurs. 

However, there is still one more step that needs to happen before you are officially considered pregnant.

After conception, the fertilized egg must move to the uterus and implant into the uterine lining or wall. This is called implantation, and it typically takes place 7 to 10 days after fertilization.

Why Does Conception Matter?

Conception is a critical step in the pregnancy process. If a woman does not ovulate, she cannot get pregnant naturally. Likewise, if a man’s sperm is not strong enough to swim up to the fallopian tubes, it will not be available to fertilize an egg, and conception cannot happen.

It’s important to point out that fertility treatments may increase your chances of getting pregnant.

As a woman ages, the odds of getting pregnant decreases. That’s because, at birth, there are about one to two million eggs present in the ovaries. This is the number of eggs you will have during your lifetime.

But over time, fertility can drop as the number of eggs decrease via follicular atresia (the process in which some eggs, that are not released during ovulation, breakdown). In fact, at puberty, the number of eggs has dropped to about 300,000 to 500,000. This number continues to decline each year. And by age 37, the average woman has 25,000 eggs.

In addition to the number of eggs decreasing, the quality of the eggs also changes. As a woman gets older, the remaining eggs are more likely to have abnormal chromosomes.

Plus, age also increases the risk of uterine fibroids and endometriosis, which can affect fertility. All of these factors impact ovulation, and consequently, the ability to conceive. 

In order for conception to take place, a man’s sperm must also be healthy and able to fertilize an egg. Although several sperm are available to make the trip to the fallopian tube, only one is needed for fertilization.

According to a 2011 review published in the journal Reviews of Urology, male-related fertility is an issue with age as sperm concentrations, motility, and volume all decrease as men get older.

A Word From Verywell

Conception requires an egg to be fertilized by sperm. This may not sound like a complicated process, but it is. Both female and male fertility impacts the ability to conceive. And even if you or your partner do not have any fertility-related issues, there is no guarantee that conception will occur after having sex. This is a process that takes time and patience. 

To increase the odds of conceiving, it’s a good idea to track your menstrual cycle to get a feel for when you ovulate. Once you identify your ovulation window, aim to have sex near the time of ovulation. Daily is best, but every other day works too!

If you’re having sex during your fertile window and not getting pregnant after six to 12 months of trying, talk to your doctor. There are several options for increasing fertility. And remember, you are not alone.

Reach out to a trusted friend or family member. Talk to a fertility specialist, or join an online fertility support group. There are a lot of people willing to listen and help guide you through this journey.

6 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American College of Obstetricians and Gynecologists. Fertility Awareness-Based Methods of Family Planning.

  2. Sakkas D, Ramalingam M, Garrido N, Barratt CL. Sperm selection in natural conception: what can we learn from Mother Nature to improve assisted reproduction outcomes?. Hum Reprod Update. 2015;21(6):711-26. doi:10.1093/humupd/dmv042

  3. Female reproductive system. Cleveland Clinic.

  4. Zhou J, Peng X, Mei S. Autophagy in Ovarian Follicular Development and AtresiaInt J Biol Sci. 2019;15(4):726-737. Published 2019 Jan 29. doi:10.7150/ijbs.30369

  5. American College of Obstetricians and Gynecologists. Female Age-Related Fertility Decline.

  6. Harris I, Fronczak C, Roth L, Meacham R. Fertility and the Aging Male. Rev Urol. 2011; 13(4): e184–e190. 

By Sara Lindberg
Sara Lindberg, M.Ed., is a freelance writer focusing on health, fitness, nutrition, parenting, and mental health.