What Causes Fatigue during Pregnancy?

prenatal health Jan 02, 2026
What Causes Fatigue during Pregnancy?

What Causes Fatigue during Pregnancy?

As a mama, I know that fatigue is one of the most common symptoms of pregnancy, affecting up to 95% of expectant mothers. So what causes fatigue during pregnancy?

You may feel that this fatigue is often most intense in the first trimester (peaks around weeks 1-12) and returns in the third trimester, while many feel more energetic in the second.

This extreme tiredness is normal and stems from your body working hard to support fetal growth.

First Trimester Fatigue

A surge in progesterone (a hormone that supports pregnancy) has a sedative effect, making you feel sleepy and sluggish.

Your body increases blood production (up to 50% more volume), making your heart work harder.

Lower blood pressure and blood sugar early on contribute to tiredness.

Emotional changes, stress, or mood swings from hormones add to mental fatigue.

Second Trimester Fatigue

Fatigue usually eases in the second trimester as your body adjusts.

If the fatigue is severe, sudden, or accompanied by symptoms like dizziness, shortness of breath, or depression, contact your healthcare provider.

There could be more serious health issues you need to check out such as anemia, thyroid problems, or other issues needing checks (e.g., blood tests).

Always prioritize rest; your body is doing amazing work!

Third Trimester Fatigue

Carrying extra weight (baby, placenta, fluids) strains your body.

Discomfort like pregnancy back pain, frequent urination, heartburn, or leg cramps disrupts sleep.

Hormones continue to play a role, plus anxiety about labor.

Fatigue during Pregnancy Causes

1. Hormonal Changes

Increased levels of progesterone and other hormones can lead to feelings of tiredness, especially in the first trimester.

2. Increased Blood Production

Your body produces more blood to supply nutrients to the growing baby, which can contribute to fatigue.

3. Lower Blood Sugar and Blood Pressure

Pregnancy can lower your blood sugar and blood pressure, making you feel more tired.

4. Physical Toll

As pregnancy progresses, the physical demands on your body increase, leading to greater fatigue.

5. Sleep Disruptions

Changes in sleep patterns and discomfort can also contribute to feelings of exhaustion.

Throughout Pregnancy

Iron deficiency anemia → Low iron reduces oxygen delivery, causing exhaustion (common as needs rise to 27 mg/day).

Nausea / morning sickness → Leads to dehydration or poor nutrition.

Other factors → Poor sleep quality, stress, or conditions like thyroid issues.

Ways to Combat Fatigue

1. Aim for 8-10 hours of sleep nightly.

2. Eat balanced meals.

3. Stay hydrated and do light exercise (e.g., walking) for energy boosts.

4. Take prenatal vitamins as recommended by your health care provider.

About the Author: Kerryn Boyle

Founder of PregActive. Kerryn Boyle holds a BSci.Degree in Exercise Science andĀ is a qualified prenatal and postpartum exercise specialist, certified personal trainer, prenatal and postnatal Pilates instructor, specialist in diastasis recti functioning, pelvic floor functioning, and prenatal yoga.

Contact KerrynĀ >

About PregActive

PregActive is an online pregnancy and postpartum fitness program designed to help women stay healthy and active throughout their journey. PregActive is the #1 pregnancy and postpartum fitness app trusted by 60,000+ mamasĀ since 2015.

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Disclaimer: This information is designed as an educational aid for the public. It offers current information and opinions by Pregactive related to women's health. It is not intended as a statement of the standard of care. It does not explain all of the proper treatments or methods of care. Always consult your health care professional. This information is not a substitute for the advice of a physician.