Your pregnancy countdown can get jumbled pretty quickly. Are you 13 weeks pregnant or 14? First trimester or second? Three months pregnant or four? Then there’s figuring out your due date — which, for ...

Corrections & Clarifications: An earlier version of this story misstated how to calculate pregnancy duration. It has since been updated. If you think there's a chance you might be pregnant, you want ...

As anyone who experiences it knows, pregnancy vastly transforms the body – and now we have the most detailed picture yet of how it affects the blood, organs and immune system on a weekly basis. This ...