Pregnancy is measured in three time periods, or trimesters, starting with the first day of the last menstrual period. During each trimester, specific fetal developments occur and the full term pregnancy is considered 40 weeks.

First Trimester (0-13 weeks)

  • Most important for fetal development
  • Baby’s organs and structures form
  • Most birth defects develop during this time
  • Most miscarriages happen during this time

Maternal changes during the first trimester include:

  • Breast tenderness
  • Headaches
  • Nausea and vomiting
  • Fatigue
  • Frequent urination
  • Mood swings

Second Trimester (14-26 weeks)

  • Fetal organs further develop
  • Movement first felt at 16-20 weeks

Maternal changes during the second trimester include:

  • Energy returns and increases
  • Nausea greatly diminishes
  • Heartburn
  • Constipation and abdominal discomfort
  • Bloating
  • Back pains
  • Leg cramps

Third Trimester (27-40 weeks)

  • Baby starts descending downwards towards the birth canal
  • Baby rotates so that the head is the closest part to the birth canal

Maternal changes during the third trimester include:

  • Hemorrhoids
  • Varicose veins
  • Difficulty sleeping and insomnia
  • Shortness of breath
  • Urinary Incontinence
  • Swelling with some fluid retention
  • Mild, irregular cramps