Pregnancy Week 4

Woman who is 4 weeks pregnant

Congratulations! Weeks four through seven are when most women discover they are pregnant. This week-by-week newsletter will keep you informed about what to expect for you and your developing baby during your pregnancy. If you have just found out that you are pregnant, you may want to begin by reading weeks 1 through 3.

Pregnancy Week 4: How is pregnancy calculated?

There is always a lot of confusion when discussing the way in which pregnancy is calculated. Since most women do not know when they conceived, pregnancy is always determined from the first day of your last menstrual period (LMP). Given that this is the way pregnancy is calculated, your pregnancy will last around 40 weeks. For more information on how pregnancy is measured, please see our information on calculating your dates.

Pregnancy Week 4: What changes are occurring in your body?

You may begin to exhibit some of the early pregnancy symptoms such as breast tenderness, headache, backache, or others. It is important to know that many of the early pregnancy symptoms are similar to those you may experience before your period. Other women may not have any symptoms of pregnancy except for a late or irregular period. If you have missed your period, then you could take a pregnancy test. This would be the earliest that a home pregnancy test can detect pregnancy.*

Pregnancy Week 4: What is happening with your baby?

There are three layers to your baby- the ectoderm, mesoderm, and endoderm. These three layers will form the baby’s organs and tissues. The ectoderm will become the nervous system (which includes the brain), skin, hair, nails, mammary glands, sweat glands, and enamel for the teeth. The mesoderm will become the heart, circulatory system, skeleton, connective tissues, blood system, urogenital system, and the muscles. The endoderm will house the lungs and develops into the lining of the gastrointestinal tract, the liver, pancreas, and thyroid.

Arm and leg buds begin developing, but are not clearly distinguishable. The placenta has also begun to form and is producing some important hormones including hCG. There is movement of rudimentary blood through the main vessels.*

Pregnancy Week 4: How big is your baby?

Babies are still very small at this point, and measures about 0.078 inches in length.*

Pregnancy Week 4: What should you plan for this week?

If your period is late or you have an irregular period, you would want to take a home pregnancy test. If the result is positive then you would want to schedule an appointment with a health care provider. Many health care providers wait to see you until you are 8 to 12 weeks pregnant.

If your test is negative and your period is late, then you should wait a week before testing again. Some women take 2 to 3 weeks after a missed period before producing a detectable level of the pregnancy hormone.

You also want to begin looking for a health care provider and decide where you will have your baby. Many doctors and midwives will allow you to arrange an appointment so that you can meet them and ask them questions before deciding if they will become your provider. For more information on choosing your health care provider, see our information on your birthing choices.

Pregnancy Week 4: Tips for making your pregnancy better

If you have not begun an exercise routine, check with your healthcare provider to see what he/she recommends. Even if you already have a routine, you might want to read about exercise during pregnancy.

Take a look at our information on:

You also want to be careful about the different medications you take during pregnancy. You should check with your health care provider before taking any over-the-counter or prescription medications. Your prenatal vitamin should contain at least .4 mg (400 micrograms) of folic acid. Prenatal vitamins normally contain .8 mg to 1 mg ( 800 micrograms to 1 millogram) of folic acid and also have a high iron content . These are important for both you and your baby.

Pregnancy Week 4: Tips for mom’s partner

Continue being open with your partner about your fears and excitement about her being pregnant. Talk about when you want to share the news with family and friends.