How Pregnancy Happens

How does pregnancy happen?

  • First, an egg cell and sperm have to connect to become a fertilized egg.
  • Eggs are released by the ovaries (ovulation) into the fallopian tubes. Sperm is released from a penis (ejaculation) in a fluid called semen (cum).
  • The egg lives for about 24 hours after it is released. If it is fertilized by sperm, it will travel down the fallopian tube into the uterus. If it attaches to the uterine wall, it becomes a pregnancy.
  • Pregnancy is not possible if there is no egg cell or no sperm.

Where do sperm and eggs come from?

  • Sperm comes from a body with a penis. Sperm production, which usually starts during puberty, happens in the testicles. Sperm is released from the penis in semen (cum) during ejaculation. Once a body with a penis begins producing sperm, they are able to continue producing sperm for the rest of their life.
  • Egg cells are stored in the ovaries of a body with a vagina. The body releases egg cells from the ovaries (ovulation) as part of the menstrual cycle. The menstrual cycle usually begins during puberty. A body with a vagina is born with eggs already inside the ovaries. Eggs continue to be released from the ovaries into the fallopian tubes as part of the menstrual cycle until the body enters menopause. Menopause marks the end of menstrual cycles and happens, on average, in someone’s 40s or 50s.

What happens during the menstrual cycle?

  • A menstrual cycle is the time from the first day of bleeding (period/moon time) to the day before the next period.
  • 28 days often describes a typical cycle length, but cycles range from 23-35 days.
  • Menstrual blood is the shedding of the lining of the uterus. This shedding (period/moon time) can last 3-5 days.
  • After menstruation, levels of the hormone estrogen start to rise and make the uterine lining thicken. At the same time, an egg cell in one of the ovaries starts to mature.
  • Hormones trigger the release of an egg from the ovary into the fallopian tube, a process called ovulation.
  • The egg lives for about 24 hours after it is released. If it is fertilized by sperm, it will travel down the fallopian tube, into the uterus. If it attaches to the uterine wall, it becomes a pregnancy.
  • Pregnancy is not possible if there is no egg cell or no sperm.
  • Sperm can live in a vagina, fallopian tubes, and uterus for up to 5 days. This means a person can be fertile for about 5 days before ovulation and 24 hours after ovulation.
  • Ovulation only occurs once per cycle, although 2 eggs may be released at a time.
  • If the egg cell is not fertilized it will disintegrate, hormone levels will drop and the lining of the uterus will be shed, starting the cycle all over again.
  • The time between Day 1 and ovulation can vary. The time from ovulation until bleeding is about 14 days.
  • Everybody is different and cycles can vary slightly in length from one to the next.

How do I prevent an unwanted pregnancy?

  • There are a variety of birth control options, including hormonal and barrier methods. See SERC’s Fact Sheet on Birth Control Methods or talk with a health care provider to learn more.
  • Condoms protect against unwanted pregnancy as well as sexually transmitted infections (STIs).

Is there a time in a menstrual cycle a pregnancy can’t happen?

There are more likely days and less likely days, but there is no safe time guaranteed to avoid pregnancy. This is because:

  • Sperm can live in a vagina, fallopian tubes, and uterus for up to 5 days. This means pregnancy is possible for about 5 days before ovulation and 24 hours after ovulation.
  • For some people, cycles can vary from one to another, and because of this, many people do not know when they are ovulating.

Is pregnancy possible without a penis ejaculating inside a vagina?

Yes, there are a few ways a pregnancy could happen:

  • Whenever a penis has an erection (gets hard), a fluid called pre-cum is released around the tip of the penis. Pre-cum can have sperm in it. If unprotected penis-vagina sex happens, even without ejaculation inside the vagina, pre-cum still enters a partner.
  • If penis ejaculation happens around the outside area of a vagina, sperm may still swim inside the body. Sometimes this is called a splash pregnancy.
  • Some people create a pregnancy through medical support called IVF or insemination.

What if a pregnancy happens?

  • In Canada, there are 3 safe and legal pregnancy options. Abortion, adoption and parenting.
  • People have different values about which option is right for them. We can hold our personal values, but we cannot force them on someone else.
  • The person who carries a pregnancy inside their body has the final decision of which pregnancy option is best for them. No one else has the right to decide this.
  • Visit womenshealthclinic.org to learn more, or speak with a counsellor about your options.

Where can I get more information?

  • From your health care provider, community health clinic, or public health nurse. If you need a regular health care provider, call the Family Doctor Finder at 204-786-7111.
  • From the Facts of Life Online: e-mail your questions to thefactsoflife@serc.mb.ca.
  • From a Teen Clinic if you are 21 or younger.
  • Our youth website, www.teentalk.ca.

Sexuality Education Resource Centre 2021

To view or download a PDF version of this information, click here: Pregnancy 2021