Conception: definition and meaning
Conception is the moment a sperm fertilizes an egg, usually in a fallopian tube, creating a single cell called a zygote. In everyday use it often means the whole process of becoming pregnant, ending when the embryo implants in the uterus about 6 to 10 days later. Conception usually happens within a day of ovulation.
How it happens, step by step
- [Ovulation](/glossary/ovulation): an egg is released and swept into a fallopian tube. It survives about 12 to 24 hours.
- Sperm meet the egg: sperm can live up to about 5 days in fertile cervical mucus.
- Fertilization: one sperm enters the egg, forming a zygote.
- Travel and division: the cells divide into an embryo as they move to the uterus.
- [Implantation](/glossary/implantation): the embryo attaches to the uterine lining and starts making hCG.
When it can happen in your cycle
Because sperm last longer than the egg, the fertile window is about six days: the five days before ovulation plus ovulation day. The two days before ovulation carry the highest chance. Estimate dates with the conception calculator.
Why it matters
Doctors date pregnancy from the first day of your last period, not from conception, so at conception you're already "two weeks pregnant" on paper. For couples trying, about 8 in 10 conceive within a year. Trying can be an emotional rollercoaster, especially in the two-week wait, and many people notice their mood rising and falling with each cycle.
See a doctor if you've been trying for a year (six months if you're 35 or older), or sooner if periods are very irregular, absent or very painful.
Frequently asked questions
How soon after sex does conception happen?
Anywhere from minutes to about five days, depending on when you ovulate, because sperm can wait in the reproductive tract.
Can you feel conception?
No. Fertilization causes no sensation. Early pregnancy signs usually start after implantation, around when your period is due.
Sources
- NHS: Trying to get pregnant
- Wilcox AJ, Weinberg CR, Baird DD. Timing of sexual intercourse in relation to ovulation. NEJM (1995)
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
Conception calculator: when did I conceive?Conception calculator: enter your due date to find your likely conception date (due date minus 266 days) and the window of days the sex could have happened.
Fertile window: definition and meaningThe fertile window is the six days each cycle when sex can lead to pregnancy. How it's worked out, when it falls, and why it isn't a contraceptive tool.
Implantation: definition and meaningImplantation is when a fertilized egg attaches to the lining of the uterus, usually 6 to 10 days after ovulation. What happens, timing and signs.
What is a zygote?A zygote is the single cell formed when a sperm fertilizes an egg. How it becomes a blastocyst, when it implants, and how it fits into early pregnancy.How many days a month are you fertile?How many days are you fertile? About 6 days each cycle: the 5 days before ovulation plus ovulation day. Which days are most fertile and why timing varies.