Technically, by the time you are considered four weeks, or one month into your pregnancy, your baby has only been developing for two weeks. This is because a pregnancy is calculated from the first day of your last menstrual cycle. For most women, this is at least two weeks before conception even occurred. In the first month, your baby’s development takes you into your sixth week of pregnancy.
7 Days Old
By the fetal age of seven days, your baby is still considered an embryo and has just burrowed into your womb and started to create the connections that will support him for the next nine months. This little embryo has already started to grow cells that will become the brain, spinal cord and heart. Although growth and development is happening quickly, it is still too early to get a positive pregnancy test.
Now the size of a poppy seed, your baby has an amniotic sac, amniotic fluid and a yolk sac. The yolk sac temporarily provides the nutrients needed to your baby as the placenta is still developing. The placenta has formed enough to produce human chorionic gonadotropin (hCG), the hormone detected by pregnancy tests. The American Pregnancy Association (APA) reports that a few main blood vessels have formed, as the start of the circulatory system, there is even some blood flowing through these vessels.
21 Days Old
Your fetus has grown to the size of a sesame seed that, on closer inspection, resembles a fish or tadpole, rather than a human baby. He will have arm and leg buds, and his heart will have just started to beat, although the heartbeat probably is not strong enough to hear through a Doppler just yet.
28 Days Old
Those arm and leg buds have now progressed to have webbing that eventually will be your baby’s fingers and toes, states the APA. He is now measurable at 1/2-inch to 3/4-inch. More complex development of his face and jaw structures, lungs, digestive tract and brain is now starting. Dark spots on the face are the start of his eyes and nose. Some lucky moms can now hear the heartbeat, and most should have a positive pregnancy test.
What You Are Feeling
The early symptoms of pregnancy vary for each woman and for each pregnancy. For all that is happening with your baby, you may feel nothing at all, only feel normal pre-menstrual symptoms or are already learning how “morning” in the term “morning sickness” is a misnomer. In these first weeks, some women may feel a hardening of the uterus, slight cramping, exhaustion, stomach upset, increased sense of smell, while others do not feel pregnant at all. All these are normal signs of pregnancy, but, if you have concerns, discuss these with your doctor.
- grossesse 83 image by Nathalie P from Fotolia.com