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.
PREGNANCY CALENDAR: A week-by-week
- Trimester 1
- Trimester 2
- Trimester 3