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.
Frequent nausea is also a symptom of pregnancy. It is a myth that nausea only happens in the morning when a woman is pregnant; in fact, it can occur any time of day. Other medical conditions can cause nausea, including inner ear infections, which may cause dizziness, leading to a feeling of nausea.