First trimester
Learning Center
1st trimester pregnancy: What to expect
The first few months of being pregnant can bring physical and emotional changes, such as breast tenderness, nausea, anxiety and excitement.
Ankylosing spondylitis
Learn about this inflammatory disease that can cause some of the vertebrae in the spine to fuse over time.
Birth control pills: Harmful in early pregnancy?
If you took birth control pills before you knew you were pregnant, the risks of birth defects are low.
Different types of COVID-19 vaccines: How they work
Find out how different COVID-19 vaccines cause your body to create antibodies that will fight the COVID-19 virus.
Fetal development: The 1st trimester
Fetal development begins before you even know you're pregnant. Here's what happens early on.
Implantation bleeding: Common in early pregnancy?
Implantation bleeding is a common early pregnancy symptom. Understand why it happens.
Multiple sclerosis
This nervous system disorder causes a range of symptoms — and while there's no cure, it's possible to have long periods of remission.
Nausea during pregnancy: A good thing?
Morning sickness is common during pregnancy. Understand what nausea and vomiting might mean while you're pregnant.
Prenatal care: 1st trimester visits
Prenatal care can help ensure a healthy pregnancy. Here's an overview of first trimester visits.