All about baby
Until now your baby’s head has grown quicker than anything else, but its body is catching up and is beginning to look more in proportion. However your baby has not yet developed a layer of fat, and its skin is still very thin.
The bones are starting to harden now. Your baby's head is held high and limb movements are co-ordinated, so that it can now make a fist, grip firmly and suck its thumb, which you might be able to see on an ultrasound. Your baby even starts to make rooting movements, as if searching for a nipple.
Your baby's face is now becoming much more detailed. The eyes have come closer together so that they face forward, and eyebrows and eyelashes are starting to grow. Although your baby’s eyelids will remain closed until about week 25, it can already sense changes in light through the thin skin.
- Measures about 12 cm crown to rump
- Weighs in at around 3oz
Over to you
If your pregnancy is straightforward, these are probably the weeks when you will feel at your best. Your heart rate has now increased by about 20%, so you are benefiting from an increased flow of blood throughout your body. As a result your skin is firmer and smoother and you may be glowing with health.
Less welcome symptoms are never far behind though, and you may become constipated as the hormone progesterone slows down your digestion and your growing uterus pushes on your bladder and bowel. Drinking two litres water each day should help, as will including extra fibre in your diet.
Added to that, high hormone levels can cause nasal congestion by swelling the mucous membranes. Your increased blood supply can also put pressure on the capillaries in your nose, causing nosebleeds. Increasing in your consumption of vitamin C-rich foods may help, but don't use nose drops unless recommended by your doctor or midwife.
In the know
Throughout your pregnancy, you will be given regular checks and offered screening tests by your midwife or doctor to ensure that both you and your baby are in good health.
Not all hospitals routinely provide all the screening tests available. If they are not available locally, you can be referred to another centre where they are performed. It’s worth asking your midwife or GP which tests are available at your local hospital. However, here’s a quick guide to the most common tests at around 16 weeks:
Ultrasound scan
A further scan, usually referred to as an anomaly scan, is normally performed at approximately 18-20 weeks to detect serious abnormalities such as spina bifida and hydrocephalus, as well as to check on the baby's development. An ultrasound scan is a non-invasive technique and there is no known risk to the health of either mother or baby.
The AFP Blood Test - Maternal Serum Alpha Feto Protein
This simple blood test, carried out between week 16 and 18, is a screening procedure - not an accurate diagnostic test - to measure your level of alpha feto protein. A high level indicates the possible presence of a neural tube defect, like spina bifida . A low level indicates the possible presence of Down's Syndrome. But even if a high or low AFP level is detected, it doesn't necessarily mean there's something wrong with your baby. Other tests, such as a detailed ultrasound scan and/or amniocentesis, are required to confirm the presence of a neural tube defect. The AFP blood test carries no risk to you or your baby and the results are normally available within a few days to a week.
Amniocentesis
Amniocentesis is usually carried out between the 16th and 20th weeks of pregnancy. Its main purpose is to detect chromosonal disorders, like Down's Syndrome. A fine needle is inserted into the mother's abdomen and a small amount of the amniotic fluid surrounding the baby is withdrawn. The fluid is then sent to the laboratory for testing. The results for detection of neural tube defects and other structural abnormalities are normally available within a week. Results will take about three or four weeks for other conditions such as Down's Syndrome; Turner's Syndrome, inherited metabolic disorders and certain sex-linked conditions. Amniocenetesis carries a slight risk of miscarriage (less than 1%) so the test is not performed routinely.
Chorionic Villus Sampling - CVS
CVS is used to diagnose conditions which otherwise couldn’t be detected until about week 16. This test is usually only carried out if a woman is considered to have a greater risk of carrying a baby with an abnormality. It may be carried out at 10-14 weeks, or possibly at 18-20 weeks if the second ultrasound indicates there might be a problem.
During the test an ultrasound is used to show the position of the placenta, a tiny fragment of which is removed for tests. Results are available fairly rapidly - from 2-12 days. It’s not certain what the miscarriage rate is for the CVS test in the first trimester, although it's thought to be about 2%. However, if CVS is performed around the 18 week stage, then the risk of miscarriage is probably about the same as for amniocentesis.
Go to next week's article: Pregnancy Week 17
Please note that the contents of this section are for information only and are not intended as medical advice or as a substitute to your doctor's advice. For medical care and advice, you should consult your doctor on a regular basis. If you have any problem which concerns you, consult your doctor immediately.
