Your Baby's Development
This may sound strange, but you're still not pregnant! Fertilization of your egg by the sperm will only take place near the end of this week — read more about fertilization in the Your Body section below.
Although you'll have to wait to find out what color to paint the nursery, your baby's gender will be determined at the moment of fertilization. Out of the 46 chromosomes that make up a baby's genetic material, only two — one from the sperm and one from the egg — determine the baby's sex. These are known as the sex chromosomes. Every egg has an X sex chromosome; a sperm can have either an X or a Y sex chromosome. If the sperm that fertilizes your egg has an X chromosome, you'll have a girl; if it has a Y chromosome, your baby will be a boy.
Your uterine lining, which will nourish the baby, is developing, and your body secretes follicle-stimulating hormone (FSH), which stimulates an egg to mature. At the end of this week, you will be at the midpoint of your menstrual cycle (if you have a regular 28-day cycle), and ovulation will occur (your ovary will release an egg into the fallopian tube).
This is when you're most likely to conceive. If you have sexual intercourse without protection around the time that you ovulate, you can become pregnant. After your partner ejaculates, millions of sperm travel through the vagina, and hundreds make it to the fallopian tube, where your egg is waiting. One sperm generally succeeds in penetrating the egg, and fertilization takes place. When that happens, you will be pregnant — although you will not be feeling any body changes just yet.