Pregnancy Overview

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.

The information contained below is for general patient education. Ask your OB/Gyn about specific developmental milestones and symptoms you experience in each trimester.


The First Trimester (0-13 weeks)

  • Most important for fetal development
  • Baby’s organs and structures form
  • Majority of birth defects at this time as do miscarriages

Maternal changes during the first trimester include:

  • Breast tenderness
  • Headaches
  • Nausea/Vomiting
  • Fatigue
  • Frequent urination
  • Emotional fluctuation of extremes and sensitivity


The 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


The Third Trimester (27-40 weeks)

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

Maternal changes during the second trimester include:

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


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