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.
Some studies suggest that as many as 7 out of 10 women will experience pregnancy-induced nausea. Also known as morning sickness, pregnancy-induced nausea is one of the most common symptoms of pregnancy. Contrary to popular belief, morning sickness can occur at any time of the day, not just during the morning.