Your Baby's Development
Your baby now weighs about 3.9 ounces (110 grams) and measures
about 4.7 inches (12 cm) in length from crown to rump. Your baby
can hold his or her head erect, and the development of facial
muscles allows for a variety of expressions, such as squinting and
frowning.
Your Body
Between weeks 16 and 18 of pregnancy, your health care provider
may offer you the
maternal blood screening test
, also known as a "triple marker" test or "triple
screen," which measures the levels of alpha-fetoprotein (AFP),
a protein produced by the fetus, and the pregnancy hormones hCG and
estriol in the mother's blood. The test is sometimes called a
quadruple screen when the level of an additional substance, called
inhibin-A, is also measured. The results of these tests can tell
moms whether their babies are
at risk for
(not whether they have) neural tube defects such as
spina bifida
or chromosomal abnormalities such as
Down syndrome
. Out of every 1,000 women who take these tests, about 50 will have
abnormal results, but only one or two women will actually have
babies with a problem. Talk to your health care provider about the
risks and advantages of these tests.
Note: All information is for educational purposes only. For specific medical advice,
diagnoses, and treatment, consult your doctor.
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