Stages of Pregnancy and Fetal Development by Month: The Comprehensive Guide 2026 | Dr. Mohamed El-Senity

Stages of Pregnancy and Fetal Development by Month

The Comprehensive Guide to the 9-Month Journey: Your Baby's Development Month by Month

Dr. Mohamed El-Senity

Dr. Mohamed Abdel Fattah El-Senity

Consultant Obstetrics and Gynecology - Ain Shams University

Expert in Pregnancy and Childbirth Follow-up

Quick Answers

When does the fetal heartbeat start?

In the fifth week (first month).

When does the mother feel movement?

From the fourth or fifth month.

When is the baby's gender determined?

It can be seen via ultrasound from the fifth month.

When is fetal development complete?

End of the ninth month (week 39).

How to Confirm Pregnancy?

Early Signs of Pregnancy

  • Missed Period: The first and most important sign.
  • Morning Sickness: Especially in the first few weeks.
  • Breast Swelling and Tenderness: Due to hormonal changes.
  • Extreme Fatigue: Feeling unusually exhausted.
  • Frequent Urination: Due to increased body fluids.

Ways to Confirm Pregnancy

Home Pregnancy Test

Detects the pregnancy hormone (hCG) in urine. Best time: A week after a missed period. Accuracy: 97-99%.

Blood Test

More accurate than a urine test. Detects pregnancy days before the expected period. Precisely determines hCG levels.

Ultrasound (Sonogram)

The gestational sac can be seen starting from the fifth week. The heartbeat can be heard starting from the sixth week.

Golden Tips for Pregnant Women

Proper Nutrition

  • Folic Acid: 400 micrograms daily (prevents neural tube defects).
  • Iron: Red meat, spinach, lentils.
  • Calcium: Milk, yogurt, cheese.
  • Protein: Eggs, chicken, fish, legumes.
  • Vegetables and Fruits: 5 servings daily.

Avoid These Things

  • Smoking and Alcohol: Dangerous for the fetus.
  • Excess Caffeine: Maximum 200 mg (one cup of coffee).
  • High-Mercury Fish: Large tuna, shark.
  • Raw Meat: Sushi, undercooked meat.
  • Unprescribed Medications: Some drugs harm the fetus.

Exercise and Activity

  • Walking: 30 minutes daily.
  • Swimming: Safe and beneficial throughout pregnancy.
  • Prenatal Yoga: Strengthens muscles and calms nerves.
  • Avoid: Vigorous sports and jumping.

Signs Requiring an Immediate Doctor Visit

  • Vaginal Bleeding: Any amount of blood.
  • Severe Abdominal Pain: Especially if accompanied by bleeding.
  • Continuous Severe Headache: With blurred vision.
  • Sudden Swelling: In the face, hands, or feet.
  • Cessation of Fetal Movement: In the later months.
  • High Fever: Over 38°C (100.4°F).
  • Fluid Leakage: Could be amniotic fluid leaking.

1 The First Month of Pregnancy

Fetus in the first month
Sesame Seed
Size
65
Beats/Min
3 Layers
Cells Forming

During the first week, the body sheds the uterine lining during the menstrual period, then prepares to create a new one that acts as a new nest for the fertilized egg.

What Happens to the Eggs

At this stage, about a thousand eggs make their way to mature, but only twenty eggs mature, inside fluid-filled sacs called follicles.

The Fertilization Process

Out of millions of sperm, only a few hundred enter the race. The egg needs 12-24 hours to be fertilized. Pregnancy usually occurs between day 14-17 of the cycle.

Beginning of Organ Formation

Three basic layers of cells begin to form:

  • First: Nervous system, hair, and skin.
  • Second: Digestive system, liver, and pancreas.
  • Third: Skeleton and muscles.

For the Mother

You may feel a big change this month. Many women discover their pregnancy now. Mild bleeding might occur upon implantation, which is normal.

2 The Second Month of Pregnancy

Fetus in the second month
2.5 cm
Length
2 grams
Weight
150
Beats/Min

Week Five - The Heart Begins to Beat

The heart starts beating this week. Most body organs are developing. The neural tube begins to form. Taking folic acid is highly important to prevent neural tube defects.

Week Six

The fetus's size increases threefold. The heartbeat regulates at 150 beats per minute. Half of the brain is formed. Kidneys, liver, and facial features begin to develop.

Weeks Seven and Eight

  • The fetus is about 1 cm long, and the brain grows by 35%.
  • Fingers and toes begin to form.
  • Nerve cells grow at a rate of 100,000 cells per minute.
  • The genital area appears (difficult to determine gender yet).

For the Mother

Extreme fatigue, dizziness, and imbalance, especially in the morning, occasionally vomiting, and constipation. It is recommended to eat fresh vegetables and fruits and drink fluids.

3 The Third Month of Pregnancy

Fetus in the third month
7.5 cm
Length
24 grams
Weight
180
Beats/Min

Weeks Nine and Ten

All essential body parts are present now. The heart has finished dividing into four chambers. The ears form, hair follicles develop, and genitals appear.

Weeks Eleven and Twelve

  • The fetus can open and close its hand.
  • The digestive system begins working.
  • Cartilage turns into real bone.
  • Starts to suck its fingers (its new hobby!).
  • If it's a girl: the ovaries contain 2 million eggs.

For the Mother

Energy gradually increases and fatigue decreases. The belly begins to show. The uterus rises from the pelvis. Light exercise and swimming are recommended.

4 The Fourth Month of Pregnancy

Fetus in the fourth month
10-14 cm
Length
70-140 grams
Weight
Forming
Fingerprints

The body and limbs grow faster than the head. Fine hair begins to appear on the scalp. The fetus moves its hands and feet naturally.

Distinct Developments

  • Distinctive fingerprints form.
  • Facial muscles develop.
  • Neck vertebrae become longer.
  • Begins to drink amniotic fluid.

For the Mother

The uterus is about the size of a fist. Energy increases and fatigue drops. You may feel very light fetal movements.

5 The Fifth Month of Pregnancy

Fetus in the fifth month
20-25 cm
Length
200-300 grams
Weight
Known
Gender

The mother is now halfway to delivery! The first movements of the baby can be clearly felt.

Important Developments

  • The body secretes a fatty substance that protects the fetus's skin.
  • Senses are more developed.
  • The skin turns pink.
  • If it's a girl: a reserve of 6 million eggs.
  • The gender of the fetus can be determined by ultrasound.

For the Mother

The top of the uterus can be seen at the navel. Weight gain continues. Energy is high.

6 The Sixth Month of Pregnancy

Fetus in the sixth month
30-35 cm
Length
500-750 grams
Weight
Opens
Eyes

Weeks Twenty-Five to Twenty-Seven

  • Responds clearly to external sounds.
  • The brain is more developed.
  • The lungs form airways.
  • Opens its eyes for the first time in week 27.
  • Sleep patterns become more regular.

For the Mother

You may feel abdominal pain (contractions due to the enlarging uterus). The fetus's sleep and wake periods have become regular.

7 The Seventh Month of Pregnancy

Fetus in the seventh month
38-42 cm
Length
1-1.3 kg
Weight
Complete
Hearing

The baby can cry and shed tears! The iris of the eye is complete and the eye color is set (may change after birth).

Developments in Weeks 28-31

  • Heart rate is 140 beats/minute.
  • The brain and nervous system fully develop.
  • The immune system begins to develop.
  • The skull bone is flexible (the soft spot does not close until a year and a half).

For the Mother

Abdominal cramps, leg pain, shortness of breath, and mood swings. It is recommended to have prenatal checkups every two weeks.

8 The Eighth Month of Pregnancy

Fetus in the eighth month
43-47 cm
Length
1.7-2.5 kg
Weight
Complete
Lungs

If born now, the baby can survive and grow outside the womb! The fetus recognizes the mother's voice and responds to it.

Important Developments

  • Lungs are almost complete.
  • 97% of fetuses take a head-down position.
  • The skin is smoother.
  • It sheds the fine hair that covered its body.

For the Mother

General fatigue, weight gain, anxiety about childbirth. Slight urine leakage may occur when coughing or sneezing. It is recommended to avoid caffeine.

9 The Ninth Month of Pregnancy

Fetus in the ninth month
48-52 cm
Length
3-3.5 kg
Weight
Fully
Grown

The fetus is fully grown and ready to be born! The body continues to store fat to regulate its temperature in the outside world.

Preparing for Birth

  • Lungs and brain continue to grow until week 39.
  • The fetus's head points downward toward the pelvis.
  • Movement is less due to tight space.
  • Only 5% of babies are born on their exact due date!
  • Skull flexibility eases natural childbirth.

Important Information

Most women give birth between week 38 and 42. No need to worry if birth does not happen on the exact due date.

For the Mother

Pain in the lower thighs due to pressure from the baby's head. Fatigue and boredom from the long pregnancy period. Relax and wait for your new baby!

Frequently Asked Questions

When does the fetal heartbeat start?
The heartbeat begins in the fifth week of pregnancy (the first month), but it is clearly heard on ultrasound starting from the sixth week.
When does the fetus move and when can I feel it?
The fetus moves from the seventh week, but the mother feels the movement starting from the fourth or fifth month (week 16-20).
When can the gender of the fetus be known?
Gender is determined at fertilization, but it can be seen via ultrasound from the fifth month (week 18-20).
Is giving birth in the seventh month dangerous?
Giving birth in the seventh month is possible and most babies survive, but they may need an incubator until their lungs are fully developed.
What is the normal fetal weight at birth?
The normal weight is between 2.5 - 4 kilograms. The average is about 3.2 kg.
Is a decrease in fetal movement dangerous?
A decrease in movement in the last months is normal due to tight space. However, if you notice a complete absence of movement, consult your doctor immediately.

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