The fourth week of pregnancy is the week that most new moms find out that they are pregnant by taking a home pregnancy test. You are already four weeks pregnant by the time you miss your menstrual period and find out that you are pregnant. The first three weeks of pregnancy are bonus weeks when you do not even know that you are pregnant yet. Your pregnancy is calculated starting with the first day of your last menstrual cycle. This calculation will determine your due date. Your due date will be forty weeks after this date.
Pregnancy Week 4: Baby’s Development
The embryo implanted in your uterus at the end of week three. In week four, this embryo will now divide. A portion will become the placenta and the other half is your baby. Your baby’s entire genetic makeup is already in its proper place. Will your baby have brown hair, or blue eyes? Will your baby be a boy or a girl? That information is there from the moment of conception.
There is more information stored in your baby’s cells than just what your baby will look like by your fourth week. The cells that are forming your little one are broken into three layers. The building blocks of your baby’s digestive system, liver, and lungs are present in the innermost layer called the endoderm. The middle layer, called the mesoderm, will develop into your baby’s heart, bones, kidneys, muscles, and sex organs. The outer layer is the ectoderm. The ectoderm will form your baby’s skin, nervous system, hair, and eyes.
Pregnancy Week 4: Tests
You will now have officially missed your period and can take a home pregnancy test in order to detect the human chorionic gonadotropin hormone (hCG). This hormone starts to increase and doubles every day. Some early pregnancy tests can measure a smaller amount of hCG in your urine. If you take an early pregnancy test before your fourth week of pregnancy and it comes out negative, there is a possibility that the result can be false. The test may not be sensitive enough to pick up the low level of hormones in your urine.
One of the most reliable early home pregnancy tests is First Response. This test accurately measures a very low amount of hCG in your urine. Click here to read a detailed review of First Response home pregnancy tests.
Pregnancy Week 4: What mom is experiencing, Pregnant or PMS?
At this point you may not be experiencing any of the common symptoms of pregnancy. Some women experience cramping that is similar menstrual cramps. Others may have severe mood swings. Tender breasts are also a common complaint starting in the fourth week of pregnancy. These symptoms of pregnancy are often confused with premenstrual symptoms.
The roller coaster of pregnancy is just beginning. Each week your baby is developing and you are experiencing something new. Congratulations!
Click here to find more information on your pregnancy and baby’s development.
Fit Pregnancy (2009). Pregnancy Calendar. Retrieved: April 8, 9, 2009. Web Site: fitpregnancy.com/calendar/40251887.html
Myers-Gorrie, Trula, Slone-McKinney, Emily, & Smith-Murray, Sharon (1998). Foundations of Maternal-Newborn Nursing (2nd ed.). Philadelphia, PA: W. B. Saunders Company.
What to Expect (2009). Weekly Pregnancy Calendar. Retrieved:April 8, 9, 2009. Web Site: whattoexpect.com/pregnancy/week-by-week/landing.aspx