A full-term pregnancy is divided into three trimesters up to 40 weeks, beginning on the first day of the last menstrual period. Every trimester, the fetus experiences certain developmental milestones. To learn more about the stages of pregnancy, let's continue reading.

Stages of pregnancy month by month :

Pregnancy is divided into three stages, each referred to as a trimester. It takes about three months to complete each trimester. Your doctor will most likely discuss fetal development in terms of weeks. Therefore, if you are three months along, you are probably approximately 12 weeks along. You will observe noticeable changes in the fetus and yourself during each trimester.

Although the time can vary, the three trimesters are as follows:

• First trimester: 1–12 weeks

• Second trimester: 13–28 weeks

• Third trimester: 29–40 weeks

A fourth trimester, or the three-month adjustment period following delivery, is also occasionally mentioned. Pregnancy is traditionally thought of being a nine-month process. But this isn't always the case. Typically, pregnancy lasts for around 40 weeks or 280 days. You could be pregnant for nine or ten months, depending on the months you stay pregnant (some are shorter than others) and the week you give birth. It is both healthy and absolutely normal.

When your pregnancy is nearing its end, you may hear several alternative names for when you will go into labour. These classifications apply to the final few weeks of pregnancy. Additionally, they are used to keep an eye out for specific issues in neonates. 

• Early pregnancy - Babies born during the early term or earlier may be more likely to experience breathing, hearing, or developmental issues than babies born a few weeks later during the full-term period.

• Late pregnancy - A pregnancy is considered late-term if it is between 41 and 41 weeks and 6 days along. Post-term pregnancy is defined as one that is 42 weeks or longer. The likelihood of developing health issues such as postmaturity syndrome, low amniotic fluid, and larger-than-average birth weight can rise during late-term and post-term pregnancy.

Trimester breakdown:

The fetus goes through a lot of changes during a normal pregnancy. Therefore, there are different fetal phases of pregnancy where we may see differences in the fetus during stages of gestation. Your baby goes through numerous phases of development, beginning as a blastocyst, developing into an embryo, and then becoming a fetus. Around the fifth week, your baby's future heart cells will begin to flicker. At 27 weeks, they will have regular sleep and wake cycles, and at 39 weeks, your baby will be physically developed. Let's now examine pregnancy trimesters or stages in more detail.

First trimester:

The first trimester begins at conception and lasts 12 weeks. It refers to the first three months or the beginning of the pregnancy. The fertilised egg will grow throughout this trimester from a few cells to a fetus with the baby's features. You'll need to watch what you eat and make a few minor lifestyle adjustments. You can adhere to a pregnancy diet and cut back on a few habits like drinking and smoking.

Month 1 (Week 1 to Week 4) - 

• The amniotic sac and placenta both develop in parallel with the growth of the fertilised egg. 

• A primitive face with huge, dark circles for eyes will develop throughout the first few weeks. 

• Currently, development is occurring in the throat, lower jaw, and mouth. 

• Blood cells are developing and circulation will begin shortly. 

• The small "heart" tube begins to beat at a rate of 65 beats per minute by the end of the fourth week. By the conclusion of the first month, the fetus is about 1/4 inch long, which is smaller than a grain of rice.

Month 2 (Week 5 to Week 8) - 

• This month, facial features are still developing. 

• The beginning of each ear is a little skin fold on the side of the head. 

• Arms and legs are developing from tiny buds. Eyes, toes, and fingers are all growing.

• The central nervous system's neural tube, including the brain, spinal cord, and other neural tissues, is now fully developed. 

• Additionally, the sensory system and digestive systems begin to form. 

• Cartilage is being replaced by bone.

At this point, the head is out of proportion with the rest of the body. Around six weeks into pregnancy, you can hear the heartbeat can be heard. After the eighth week, the term "embryo" is replaced by "fetus" by medical professionals. By the conclusion of the second month, the fetus is about 1 inch long.

Month 3 (Week 9 to Week 12) - 

• The arms, hands, fingers, feet, and toes are fully formed at this stage.

• The fetus begins to explore by opening and closing its fists and lips. 

• The development of external ears and the growth of fingers and toenails.

• Teeth are forming beneath the gums.

• The reproductive organs also grow, but it might be challenging to tell a baby's sex from an ultrasound.

• The liver generates bile, and the urinary and circulatory systems are also functioning normally.

By the conclusion of the third month, the fetus is fully developed. All organs and extremities are present but still in the developmental stage. After the third month, the fetus is about 4 inches long. After three months, the likelihood of miscarriage significantly decreases as most of the important development has taken place.

Second trimester:

The second trimester lasts for weeks 13 to 27. It is frequently the most comfortable stage for the majority of pregnant women. Most of your early pregnancy symptoms will go away, and you'll probably feel more energised throughout the day and sleep better at night.

Month 4 (Week 13 to Week 16) - 

• The fetal heartbeat can now be heard using a gadget known as a Doppler.

• Fingers and toes are clearly visible.

• Eyebrows, eyelashes, hair, nails, and eyelids are all developed.  

• Bones and teeth get denser. 

• The baby can yawn, stretch, and make faces.

• Thereafter, the nervous system will begin to work. 

• The reproductive organs and genitalia are now fully developed, and ultrasound can predict whether the fetus will be male or female at birth.

• By the conclusion of the fourth month, the fetus is about 6 inches long. 

Month 5 (Week 17 to Week 20) - 

• The fetus might be moving around. 

• The fetus' muscles are growing and getting stronger. The first motion is referred to as quickening and can resemble a flutter.

• The head begins to sprout hair. The back, temples, and shoulders are covered in lanugo, a fine, silky hair. This hair protects the fetus and sheds towards the end of your baby's first week.

• The skin is coated by a whitish covering known as vernix caseosa. This "cheesy" material shields the fetal skin from contact with amniotic fluid. It sheds just before birth.

• By the conclusion of the fifth month, the fetus is about 10 inches long.

Month 6 (Week 21 to Week 24) - 

• The fetus's skin is now visible inside the uterus, and it is reddish, wrinkled, and translucent, revealing veins. The toe and fingerprints are visible. 

• Eyelids start to separate, and eyes begin to open.

• The fetus moves in response to sounds or quickens its heart rate. 

• You might see jerking movements if the fetus hiccups.

• With intensive care, a prematurely born baby may live past the 23rd week.

• By the conclusion of the sixth month, the fetus is about 12 inches long.

Month 7 (Week 25 to Week 28) - 

• The developing fetus continues to develop body fat reserves. Currently, hearing is fully developed. 

• The fetus moves about frequently and reacts to stimuli like light, pain, and sound. Amniotic fluid begins to diminish.

• If your kid is born early, it will probably live to be at least seven months old.

• By the conclusion of the seventh month, the fetus is around 14 inches long.

Third trimester:

The third trimester, which is the final stage of pregnancy, lasts from the 28th week until the baby's birth. In this stage of pregnancy, you'll start seeing your doctor more frequently. 

The fetus prepares for birth with each week of this final stage of development, so resist the urge to start counting down the days until your due date in the hopes that it will come sooner. The fetus rapidly increases weight during the third trimester, accumulating body fat that will be beneficial after birth.

Month 8 (Week 29 to Week 32) - 

• The fetus continues to grow and creates fat reserves for its body. 

• There might be more kicking. 

• The fetus can see and hear, and the brain is rapidly developing.

•  The lungs, however, may still be developing even though most internal systems are.

• The fetus is around 18 inches long and 2 kg in weight.

Month 9 (Week 33 to Week 36) - 

• The fetus is now continuing to develop and expand. 

• The lungs have virtually finished growing.

• The fetus has synchronised reflexes that enable it to respond to sounds, light, and touch as well as blink, close its eyes, turn its head, and grab firmly.

• The fetus is 17 to 19 inches and weighs about 3 kg.

Month 10 (Week 37 to Week 40) - 

In the final month, labour could start at any time. There may not be as much mobility since there is less movement. At this point, the foetus' posture may have changed to accommodate labour. In your uterus, it should be lying head down. As the fetus settles into your pelvis and gets ready to give birth, you could experience a lot of discomforts. The baby is now prepared to interact with the outside world. They measure approximately 18 to 20 inches and weigh 3 kg.

Prenatal development:

It is a time of remarkable shift that contributes to laying the foundation for future psychological growth. The brain develops throughout pregnancy. However, it continues to grow throughout childhood.

There are three phases of prenatal development:

• Germinal stage of pregnancy - It is the first two weeks after conception

• The embryonic stage of pregnancy - It is the third through the eighth week after conception 

• Fetal stage of pregnancy - It is the ninth week until the birth of the baby  

• Now, let's find answers to the commonly asked questions about pregnancy.

Getting ultrasounds at each stage of pregnancy is highly recommended, as they help track the baby’s growth, monitor the mother’s health, and detect any complications early. These scans provide valuable insights at different milestones, such as confirming the pregnancy, checking fetal development, and assessing overall well-being, making them an essential part of safe prenatal care.

How do you calculate pregnancy days?

The phrase "gestational age" is used to describe the time of pregnancy. The beginning of your gestational age is the first day of your last menstrual period (LMP). Gestational age can be confusing. Pregnancy is often thought to last nine months. And you are, in fact, nine months pregnant. A full-term pregnancy typically lasts about 40 weeks from LMP, or about ten months, because pregnancy is timed from the first day of your last menstrual period or about 3–4 weeks before you get pregnant. It's common for many women to forget the beginning of their most recent menstrual cycle. The most precise method for figuring out gestational age early in pregnancy is an ultrasound.

How does pregnancy start?

Sperm and an egg need to come into contact for pregnancy to happen. A fertilised egg implants in the uterine lining to start a pregnancy. Pregnancy begins roughly two to three weeks following the last sexual encounter. 

What happens in the 1 week of pregnancy?

There is only an egg and sperm waiting to be fertilised; there is neither a baby nor an embryo, at least not yet. But between weeks 1 and 2 of pregnancy—the week before and right after your last period—your body is hard at work getting ready for the ovulation event that will give birth to the baby. Your uterus is becoming ready for the arrival of a fertilised egg, but you won't know for sure until the next month whether that egg has successfully fertilised with sperm.

Should I feel pregnant at 3 weeks?

During the first three weeks of your pregnancy, you might not even be aware that you're expecting, and you might not show any early pregnancy symptoms. Ideally, the first indication of pregnancy is a missing period. Some of the symptoms can appear now or a little while later. Some women can sense or notice a few minor changes that occur during pregnancy.

What pain is normal in early pregnancy?

Taking care of your body is a great approach to giving birth to a healthy baby because a healthy woman is more likely to have a healthy baby. To prevent pregnancy issues, you must exercise caution and follow your food plan if you are pregnant. Healthy pregnancy signs include:

• Consistent development patterns are visible.

• Watch your weight gain throughout pregnancy.

• During the second trimester, you can watch the fetal heartbeat and movements.

• In the third trimester, pay attention to the fetal position. 

What is the golden period of pregnancy?

Pregnancy's second trimester is referred regarded as the "golden period" since many of the uncomfortable first-trimester symptoms go away during this time. During the second trimester, you will feel less nausea, have better sleep habits, and have more energy. However, you can experience different symptoms, like heartburn, leg cramps, constipation, back discomfort, and abdominal pain.

References

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(https://my.clevelandclinic.org/health/articles/7247-fetal-development-stages-of-growth). Retrieved on 24.02.2023

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4 - Stages of Prenatal Development; From Very Well Mind

(https://www.verywellmind.com/stages-of-prenatal-development-2795073). Retrieved on 03.03.2023

5, 7 - Month by Month; By Planned Parenthood

(https://www.plannedparenthood.org/learn/pregnancy/pregnancy-month-by-month). Retrieved on 24.02.2023

6 - How Pregnancy Happens; From Planned Parenthood 

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10 - Signs of a Healthy Pregnancy – Maintaining the Good Antenatal Care; From Chatswood Medical Center

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