Follow Step By Step On Your Pregnancy

After the long 6-day trip from the fallopian tubes, the blastocyst, which has since divided into two sections, arrives within the uterus and begins to burrow or implant into the wall of the uterus. 

At this point, the blastocyst is a grouping of cells comprised of an inner collection of cells, which will ultimately develop into the embryo and an outer shell whose purpose is to provide protection and nourishment to the growing embryo.

During this time, the amniotic sac is forming, as is the yolk sac and the placenta.
This MNT Knowledge Center feature is part of a series of articles on pregnancy. It provides a summary of each stage of pregnancy, what to expect, and insights into how your baby is developing.
You will also see introductions at the end of some sections to any recent developments that have been covered by MNT's news stories. Also look out for links to information about related conditions.

Symptoms at 4 weeks pregnant

Due to the stage of the maternal menstrual cycle, the uterus is plush and thick with blood providing the perfect environment to support the growing embryo.

During week 4 of pregnancy, your baby is growing rapidly and its development is composed of three layers - the ectoderm, mesoderm and endoderm.

Approximately 6 to 12 days following conception, some women experience mild vaginal spotting with or without mild cramping referred to as implantation bleeding, which is at times mistaken for a menstrual period.⁴
Generally, this bleeding will resolve on its own. Implantation bleeding is an early sign of pregnancy. However, if the bleeding is heavy, you are experiencing chills, fever or cramps, contact your health care provider.⁴
Bleeding during pregnancy has causes other than implantation and may be caused by sex, an ectopic pregnancy, or miscarriage.⁴
Sex can cause bleeding at any time during your pregnancy likely due to hormonal changes. If an ectopic pregnancy has occurred, this means that the embryo has implanted outside the uterus and is considered a medical emergency.⁴
Medical attention should be sought immediately if you are experiencing bleeding with pain and cramps.⁴
Miscarriage is a common occurrence with approximately 15% of pregnancies ending in loss. Call your medical provider if you have bleeding and cramping or think you may be experiencing a miscarriage.⁴
You may start to have some symptoms of pregnancy including breast tenderness, headaches, low backaches and nausea.⁵
Now may be a good time to take a pregnancy test if you are late for your period, as this is the earliest possible time that a home pregnancy test will be able to detect a pregnancy.⁵

Baby's development at 4 weeks pregnant

Your baby is growing rapidly and its development is composed of three layers, the ectoderm, mesoderm and endoderm, which will eventually form his or her organs and tissues.^3,5

 

At 4 weeks pregnant, your baby is the size of a poppy seed.

The nervous system and brain, skin, hair, nails, mammary glands, sweat glands and tooth enamel will develop from the ectoderm layer.^3,5
The baby's heart, circulatory system, sex organs, skeleton, connective tissues, blood system, urogenital system and muscles will develop from the mesoderm layer and the endoderm, will eventually encapsulate the lungs and develop into the lining of the gastrointestinal tract, liver, pancreas and thyroid.^3,5

Baby's size at 4 weeks pregnant

Right now your baby is still quite tiny, the size of a poppy seed, measuring only approximately 0.078 inches. CONTINUE READING

SOURCE: MEDICALNEWSDAILY