Mrinali was in her 29th week. She wanted to know what are the tests that need to be done during the next 3 months of her pregnancy. The doctor explained to her that - the third trimester starts from the 28th week of pregnancy and ends at the birth of the baby. The fetus is usually viable by this point of pregnancy, meaning it can survive if it is born but may need hospitalization. if it is born this early. So the tests performed during this trimester are mostly to monitor the growth of the baby and to prevent any foreseeable complications, like complications that could arise due to gestational diabetes or due to group B streptococcal infections etc.