1. When the sperm meets the egg
Fertilization
When the sperm meets the egg

2. Step 1 - Ovulation
Before a woman can become pregnant she must first release a mature egg, also known as an ovum, from the ovaries. This usually occurs towards the end of her period or right afterwards making her highly fertile and more likely to conceive a child due to the presence of the ovum. Along with the release of the female gamete, the cervix leading to the uterus and the fallopian tubes will dilate allowing sperm to enter during intercourse. The egg will only be able to be fertilized within the first hours after its initial release. If it remains unfertilized by sperm it will then be discarded during the next menstrual cycle.
Ovulation Video

3. Step 2 - Ejaculation
Sexual stimulation and friction provide the impulses that are delivered to the brain. Ejaculation is a reflex action controlled by the central nervous system. It is triggered when the sexual act reaches a critical level of excitement. It has two phases. In the first phase, the vas deferens (the tubes that store and transport sperm from the testes) contract to squeeze the sperm toward the base of the penis and the prostate gland and seminal vesicles release secretions to make semen. At this stage, the ejaculation is unstoppable. In the second phase, muscles at the base of penis contract every 0.8 seconds and force the semen out of the penis in up to 5 spurts.
The semen then enters into the female reproductive tract through the vagina in hopes of fertilizing the egg.

4. Ejaculate
Mechanics of Ejaculation

5. The Sperm's Journey to the Ovum
Fertilization Video
Vagina
Cervix
Uterus
Fallopian tube
One sperm will combine with the ovum and exchange genetic material in return creating what is called a zygote.
The zygote will then travel down the remainder of the fallopian tube and then enter the uterus where it will implant itself to continue developing into a baby.

6. How do sperm cells know where to go?
Chemotaxis - They swim to areas with a high concentration level of molecules released by the ovum.
Thermotaxis - The sperm look for the high-temperature areas of the female reproductive tract where the ovum is located.
If there is not an egg present sperm cells are known to swim around randomly in all of sorts of directions and not know where to go.

7. Interesting Facts About Fertility
The egg stays in the fallopian tube for about 3 days before making its way to the uterus.
A minimum of 22% of body fat is necessary for normal ovulation and conception.
Women reach their fertility peak in their mid 20s but after age 27 it begins to go down and it drastically decreases around the age of 37.
1 out of 10 healthy couples will experience infertility problems.
Sperm can live up to 3 days in the female reproductive tract after sex.
At the very moment of fertilization the baby's genetic profile and sex are instantly determined.