15 Surprising Ways Pregnancy Transforms Your Body --- and Your Mind

9. Your Lungs Work Overtime Too

Breathing for two? Kind of! As your pregnancy progresses, your body needs more oxygen, so your respiratory system kicks into high gear. Your lungs absorb oxygen more efficiently, and your breathing rate subtly increases. Combine that with your growing baby pressing on your diaphragm, and it's no wonder you feel winded walking up the stairs.