Final answer:
The chemistry test used to screen for Neural Tube Defects (NTD) is the measurement of maternal serum alpha-fetoprotein (MSAFP), performed as part of the second trimester maternal serum screening.
Step-by-step explanation:
The chemistry test done to screen for Neural Tube Defects (NTD) is the measurement of maternal serum alpha-fetoprotein (MSAFP). This test is part of the second trimester maternal serum screening that may also include additional markers, such as hCG, estriol, and inhibin A. Elevated levels of alpha-fetoprotein can indicate the presence of possible NTDs like spina bifida or anencephaly. Folate, a B vitamin, is crucial for neural tube development, and its deficiency can lead to such defects. The test is typically offered to pregnant women between the 15th and 20th weeks of gestation.