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.
When you experience nausea in the morning, you might think you are pregnant. Although it will sometimes cause vomiting, this is not always true. Pregnancy is most commonly associated with morning nausea, but this is not the only health condition that will do so. Nausea occurs involuntarily based on the actions of your central nervous system. If you experience morning nausea but are not pregnant, then there are many possible reasons.