Between 24 and 28 weeks, the Ob/Gyn will carry out a glucose screening take a look at to check the mom for gestational diabetes, a form of diabetes during which the mom doesn't produce sufficient insulin. Tests performed throughout this trimester embody an Alpha-Fetaprotein (AFP) or triple check -- a blood test that detects ranges of alpha-fetoprotein (a protein produced within the fetus's liver) to determine Down syndrome or spina bifida.