T cells, which are one type of white blood cell in the immune system, somehow become sensitized to proteins in the CNS. When T cells become activated, they enter the CNS through blood vessels and produce damaging inflammation.
1 Fatigue or Tiredness: Feeling fatigued or more tired than usual, is a pregnancy symptom which can also start as early as the first week after conception.  Morning Sickness or Nausea: This well-known pregnancy symptom will oftentimes show up between 2-8 weeks after conception.
Morning sickness usually starts around week six of your pregnancy. But because every pregnancy is different, this can vary from woman to woman. If you have morning sickness, you may feel queasy when you wake up. But although it is called morning sickness, nausea can strike at any time of the day or night. You're just more likely to feel sick in the morning because your stomach is empty. Certain smells may set off your nausea at any time.