15 weeks pregnant

When you are 15 weeks pregnant you may be offered a screening blood test to determine the risk of having a baby with Down Syndrome or Spina Bifida. These chromosome tests can also be referred to as the Triple Test, Triple Screen, Kettering Test or the Barts Test and is ideally carried out up to 18 weeks. When this blood test is performed they are looking for unusually high levels of a protein called Alpha-Fetoprotein (AFP -produced by the liver) which could indicate that you are carrying a baby with a neural tube defect such as Spina Bifida.

Pregnancy 15 Weeks – Molecular Estriol Structure, A Marker For Fetal Health

If an abnormal level is detected then you may be referred for further tests (such as amniocentesis) to be carried out before a definite diagnosis is determined as there are other factors that could effect these readings, such as a twin pregnancy or simply that you are further advanced in the pregnancy than was first thought. At this time they will also check for Estriol which is one of the 3 main estrogens only produced during pregnancy through the placenta which can be used as a marker for fetal health and well being.

It comes from the androgen steroid (affecting the development and growth of the male sex organs) which is produced by the fetal liver and adrenal glands. If these levels of Estriol are abnormally low in a pregnant woman then this may be an indication of congenital or chromosomal defects such as Down Syndrome or Edwards Syndrome. Another value that is measured in this test is your level of hCG (Human Chronionic Gonadotropin), either too high or too low again can be an indication of a chromosomal defect present in the fetus.

This test is used only for screening purposes to establish if a pregnancy warrants further medical investigation or not. Actual diagnosis will be determined only through further detailed medical tests. If you are considered high risk you may also have an ultrasound around now to check the baby’s size, organs and heartbeat, if not, then this will normally be carried out around weeks 18-22.

From around 15 weeks pregnant and for the duration of your pregnancy, you may begin to notice some pigment changes to your skin, affectionately known as the ‘mask of pregnancy’. This usually takes the form of skin discoloration around your face, arms, breasts and abdomen, along with darker moles and freckles. 70% of pregnant women will usually get a butterfly-shaped mark appearing on the face. The medical term for this is Chloasma (or Melasma) and is caused by a combination of Estrogen and sunlight.

This affected pigment will usually appear darker on fair-skinned women and lighter and darker skin. Many women may also notice pigment discoloration on their belly in the form of a dark line running down from the navel, this is also referred to as the ‘linea nigra’. This altered pigmentation is nothing to be concerned about, it is all part of the natural pregnancy process and should fade away after the birth of your child.

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(See Pregnancy Week 15 – The Baby’s Development)


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