First Trimester of Pregnancy
What To Expect In Weeks 1 to 12

1st trimester

First Trimester: Weeks 1-12

First Pregnancy Trimester


First Month: Weeks 1 to 4
Second Month: Weeks 5 to 8
Third Month: Weeks 9 to 12

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Even if you decide not to tell anyone you are pregnant until the first trimester is over, you will be aware of the changes starting to take place in your body. Chances are you will look pale and have bouts of morning sickness. You may be rushing to the toilet every hour with the urge to urinate and feel totally exhausted. On top of it all, you and your partner are emotionally adjusting to the idea of becoming parents and your hormones are running wild. Here are some guidelines as to what you can expect in the first 12 weeks of pregnancy. Don't forget to check out our pregnancy tips as well.

First Month: Week 1 to 4

What May Happen to You

As most women cannot always pinpoint the day of conception, the 40 week pregnancy countdown is technically calculated from the first day of your last period. This means on week 2, you are ovulating and week 3 you have conceived. In other words, you clock up 2 weeks before you are even pregnant. How's that for a head start! By week 4 implantation has taken place, the embryo has reached the uterus and is snuggling into the uterine lining where it will stay until birth. Most pregnancy symptoms do not make an appearance until about week 6, so unless you have confirmation through a home pregnancy test, you may not even be aware that you are pregnant! Some early signs to watch for are:

Spotting or Implantation Bleeding: When the fertilized egg implants in the uterus, around 5 to 10 days after conception, some light spotting may appear. This blood is lighter in color than menstruation blood, but is sometimes mistaken for it. Only about 30 percent of women experience implantation bleeding.

Other signs of pregnancy: Morning sickness, fatigue, lack of energy, need to urinate more often, flatulence, bloating, breast changes and nipple tenderness. Many of these signs may be mistaken for regular PMS symptoms. If you have not yet had confirmation of pregnancy, it is still a good idea to act as though you are, and begin your antenatal care.

Your Baby

By the end of the month your baby is still no larger than a poppy seed - but its cells are already dividing. One layer of cells known as the endoderm will develop into the digestive system, another called the mesoderm becomes the heart, bones, kidneys and muscles and the outer ectoderm becomes your baby's hair, skin, eyes and nervous system.

Second Month: Weeks 5 to 8

What May Happen to You

Every pregnancy, as every woman, is different. So you may experience all these pregnancy symptoms or none at all, or in a different order.

• Physical exhaustion and feeling constantly sleepy.
• Need to urinate frequently.
• Nausea, or morning sickness which may result in vomiting.
• Bloating, heartburn, acid reflux (GERD), flatulence, constipation in pregnancy and indigestion.
• Aversion to certain foods or smells. See: metal taste in mouth.
• Or alternatively cravings for strange foods.
• Breast becoming tender and starting to grow. Lubrication glands in the areolas (dark area around nipples) becoming prominent like goose bumps.
• Occasional headaches.
• A slight rounding of the stomach and clothes become a little tighter. By the end of this month, your uterus which is normally the size of a fist, has grown to the size of a large grapefruit.

Emotionally you may have ups and downs similar to PMS mood swings, including out of the blue weeping and irritability. Also, you might still be slightly shell-shocked at the idea of being pregnant.

Your Baby

As the embryo grows, it begins initially to look more like a tadpole with a tail than a baby. The circulatory system (which includes the heart) is the first system to be operational. By week 7 your baby is 10,000 times bigger than it was at conception, which is an amazing rate of growth. Your baby's mouth, tongue, arms and legs are starting to grow. By week 8 the embryo measures approximately 1.25cm, the size of a large raspberry. Although it is too soon to monitor, your baby's heart is beating at the rate of 150 beats a minute. You may be tempted to buy a Doppler to monitor the heartbeat, but most home Doppler kits are not nearly sensitive enough to pick up a baby's heartbeat until month five. The early stages of embryo development are very important which is why certain drugs are restricted to pregnant women particularly in this period, see taking aspirin during pregnancy. See treating colds alternative: tylenol medicine while pregnant.

Third Month: Weeks 9 to 12

What May Happen to You

As you enter the last month of your first trimester, those early pregnancy symptoms are still probably very much knocking around. Morning sickness may really have kicked in and you are probably feeling exhausted. Don't worry though; the worse will hopefully be soon behind you. Other possible developments this month include:

• Slight increase in vaginal discharges. If discharges are excessive or thick and white ask your doctor to check you for yeast infections.
• Visible veins on your stomach and legs as your blood supply pumps up the volume.
• More rounding of the stomach, clothes feeling that little bit tighter again.
• Emotional ups and downs, a feeling of disbelief, coupled with bouts of calmness.

Your Baby

Your baby has officially graduated from embryo to fetus status. By the end of week 12 your baby measures about 8-9cm long, the size of a peach. The baby's digestive system and intestines are growing, as well as its vocal chords - all the better to hear them with!

Always discuss any concerns or questions you may have on pregnancy issues with your doctor or OB/GYN. See our books on pregnancy for week by week guides.

  Related Articles on Being Pregnant

For more about your developing baby, see the following:

Prenatal Visits: What to expect in your doctor visits.
Pregnancy Diet Plan: Sample menus for breakfast, lunch and dinner.
Ultrasound Scan & Video Images: See a picture of your baby.
Ovarian Cysts In Pregnancy: Minor complications while pregnant.
Paternity Testing While Pregnant

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