Pregnancy 1st Month (week 1-4)

Week 1 & 2

This may sound strange, but for the first 2 weeks you are still not pregnant! Fertilization of your egg by the sperm will only take place near the end of the 2nd week.

And 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 46 chromosomes that make up a baby's genetic material, only two of them - one from the sperm and one from the egg - determine your baby's sex.

These are known as the sex chromosomes. Every egg has an X sex chromosome and a sperm can have either an X or Y sex chromosome. 

If the sperm that fertilizes your egg has a chromosome X - you'll have a girl and if it has a Y chromosome - your baby will be a boy! 

Fertilization and Implantation

Week 3: Fertilization 

This is it — the magic week when you conceive! 

At this stage you will not know that you are pregnant, but your body will. Your body starts to produce a hormone called Human Chorionic Gonadtrophin (HCG) which you will be able to detect in your urine in a week or so, if you take a home pregnancy test. HCG encourages the ovaries to continue to produce progesterone, preventing your body from shedding the lining of your uterus. Your immune system becomes suppressed so your body wont reject your baby as a foreign object, which is why pregnant women are susceptible to any bugs and colds going around. 

Week 4: Implantation

This is when you may first start to suspect you are pregnant. Your period hasn’t arrived (although some women do experience bleeding during pregnancy – see our bleeding during pregnancy article) and you may start to experience some symptoms of early pregnancy. Read our early signs of pregnancy article to find out what early signs you could notice. You might also be wondering when your baby might be due – our due date calculator will give you an estimated date. 

Your egg is now well attached to the inside wall of your uterus. It is sending out tiny little hair like tendrils, which will wrap around the abundant small blood vessels in the lining of your uterus and provide oxygen and nutrients to your growing baby. In normal circumstances your blood and the blood of your baby do not mix – you have a separate circulatory system. Exchange of oxygen, nutrients and waste products is made possible due to the closeness of your blood vessels to the blood vessels of the placenta. Implantation bleeding may occur for some women, resulting in some spotting at around about 10 – 14 days after conception. Some women may think they are starting to get their period, however implantation bleeding is very light and lasts only a day or two. 

This week a pregnancy test will probably be able to detect your pregnancy! 

HCG also causes the symptoms of pregnancy, which can appear this week. Fatigue, tingling or aching breasts, or nausea might lead you to believe your period will be starting any day because the first pregnancy symptoms resemble premenstrual syndrome (PMS). 

But by the end of this week, your expected period will not take place. Your pregnancy is well on its way!

The placenta, which will nourish your baby throughout the pregnancy, also begins to form.