Pregnancy Week by Week Overview

Understanding how your pregnancy develops week by week can help you know what to expect and when to seek medical care. This overview provides a general guide to pregnancy development.

What It Means

Pregnancy is typically divided into three trimesters, each lasting about 13 weeks. The weeks are counted from the first day of your last menstrual period, which means conception typically occurs around week 2-3.

First Trimester (Weeks 1-13)

Early Weeks (1-4)

• Fertilization and implantation occur
• Early pregnancy symptoms may begin
• Hormonal changes start

Weeks 5-8

• Baby's heart begins beating
• Major organs start forming
• Neural tube develops
• You may experience morning sickness, fatigue, and breast tenderness

Weeks 9-13

• Baby's features become more defined
• Fingers and toes form
• Movement begins (though you won't feel it yet)
• First trimester screening tests may be offered

Second Trimester (Weeks 14-27)

Weeks 14-18

• Baby's sex organs develop
• You may start to feel movement (quickening)
• Morning sickness often improves
• Energy levels may increase

Weeks 19-23

• Baby can hear sounds
• Hair begins to grow
• Anatomy scan typically performed
• You may feel more comfortable

Weeks 24-27

• Baby's lungs continue developing
• Rapid growth occurs
• You may experience back pain and other physical changes
• Viability milestone reached

Third Trimester (Weeks 28-40+)

Weeks 28-32

• Baby's eyes can open and close
• Brain development accelerates
• You may experience more discomfort
• Regular prenatal appointments increase

Weeks 33-37

• Baby gains weight rapidly
• Lungs continue maturing
• You may experience Braxton Hicks contractions
• Baby may move into head-down position

Weeks 38-40+

• Baby is considered full-term at 37 weeks
• Final preparations for birth
• You may experience nesting instincts
• Labor can begin at any time

What Is Normal

It's normal to experience:

• Various symptoms throughout pregnancy
• Changes in energy levels
• Emotional ups and downs
• Physical discomforts
• Concerns and questions

What Is Not Normal

You should seek immediate medical attention if you experience:

• Severe abdominal pain
• Heavy bleeding
• Severe headaches or vision changes
• Decreased fetal movement (in later pregnancy)
• Signs of preterm labor
• Any concerning symptoms

When to See a Doctor

Regular prenatal care is essential:

• First visit: As soon as you know you're pregnant
• Regular visits: Monthly until 28 weeks, then more frequently
• Immediate care: For any concerning symptoms or emergencies

Important Milestones

• Week 12: End of first trimester, risk of miscarriage decreases
• Week 20: Anatomy scan, halfway point
• Week 24: Viability milestone
• Week 37: Full-term pregnancy
• Week 40: Estimated due date

Self-Care During Pregnancy

• Attend all prenatal appointments
• Take prenatal vitamins
• Eat a balanced diet
• Stay hydrated
• Get adequate rest
• Exercise as approved by your healthcare provider
• Avoid harmful substances

Remember, every pregnancy is unique. This overview provides general guidance, but your healthcare provider can give you personalized information based on your specific situation.