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Table 1 Antenatal Tests

From: Antenatal screening and its possible meaning from unborn baby's perspective

Type of test Detectable conditions Stage of pregnancy
Invasive: mother only   
Estimation of maternal serum Neural tube defects; Down's 16th-18th week.
alphafetoprotein in maternal syndrome.  
Combined maternal blood   
Estimation of MSAFP, chorionic Down's syndrome. 16th-18th week.
gonadotropin and/or   
unconjugated oestriol.   
Invasive: both fetus and   
A test involving the insertion, Chromosomal disorders; a 12th-14th week.
through the mother's abdomen, number of hereditary disorders  
of a fine needle into the caused by a single gene; neural  
amniotic sac and the removal of tube disorders.  
amniotic fluid.   
Chorion biopsy   
A test involving the introduction Chromosomal disorders; a 8th-12th week.
through the mother's vagina or number of hereditary disorders  
abdomen of a needle into the caused by a single gene.  
womb and the removal of tissue   
surrounding the fetus.   
A test involving the introduction Chromosomal disorders; 16th-18th week.
through the mother's abdomen disorders detectable by fetal  
of an instrument enabling the blood sampling; malformations.  
examiner to see the fetus.   
A test involving the insertion of Chromosomal disorders; 15th week
a needle through the mother's disorders detectable by fetal onwards.
abdomen (where the umbilical blood sampling.  
cord of the fetus is attached to   
the placenta) and then the   
removal of fetal blood.   
Ultrasound scan   
An instrument is passed over Fetal growth and development; Any time but often
the mother's bare abdomen multiple pregnancy; about the 16th
and a picture of the fetus is malformations, including neural week to check
produced on a screen. tube defects. dates and
The mother's abdomen is X- Skeletal abnormalities requiring 20th week
rayed. This is hardly ever done a picture of the whole skeleton. onwards.