First Trimester of Pregnancy: What to Expect

For any new mother, having a baby is a magical time filled with wonder, excitement, and perhaps just a hint of nerves! As you step into the first trimester, you might find yourself feeling a whirlwind of emotions - from sheer elation to the occasional touch of apprehension, and that is absolutely normal.

Pregnancy is a beautiful journey that spans roughly 40 weeks, which is a little over nine months when counted from the last menstrual period to delivery. These 40 weeks are divided into three trimesters, each with its own unique experiences and milestones.

What Is the First Trimester of Pregnancy?

Each trimester is approximately 3 months long. The first trimester of a full-term pregnancy lasts till the 12th week of pregnancy.

A woman’s due date is typically calculated by adding 40 weeks to the first day of their last menstrual period.

How Many Weeks Is the First Trimester?

The first trimester is approximately 12 weeks long. As we already alluded to, this period starts on the first day of a woman’s last menstrual period and goes up till the 12th week of pregnancy.

Let us find out more about the development of the foetus during the first trimester.

Week one to four of pregnancy

It is likely that you would not have a visible baby bump yet. For first-time pregnancies, it is common not to start showing until around week 12.

But if you have had a baby before, you might start showing earlier. This is because the muscles in your uterus and belly may have already been stretched from your previous pregnancy.

Your little one, also known as an embryo at this stage, measures about 2mm in length, which is roughly the size of a poppy seed. Your baby is surrounded by an amniotic sac filled with fluid that acts like a cozy cushion, keeping them safe and sound. Attached to this sac is a tiny yolk sac, working tirelessly to provide all the nourishment your baby needs to thrive.

As your baby continues to develop, the outer layer will undergo a remarkable transformation, eventually becoming the placenta. This would provide your baby with oxygen and nutrients.

Week five to eight of pregnancy

Your baby’s facial features are beginning to develop, including a small nose and little eyes, that would stay closed until around week 28. Inside the womb, the baby’s brain and spinal cord are undergoing rapid formation.

At this stage, the baby has its own network of blood vessels, with a collection of them forming the umbilical cord. This cord serves as the conduit for delivering essential nutrients and oxygen from the placenta to the baby, while also eliminating waste products.

By the eighth week, your baby measures approximately 16mm, comparable in size to a raspberry. In just a week, they will double in size! The miniature head is beginning to straighten out slightly, and the arms are elongating, surpassing the legs in size as the upper body undergoes more rapid growth than the lower body. While the legs are also extending, specific features such as knees, ankles, thighs, and toes have yet to form.

Around this time, the embryo transitions into a “foetus,” a term derived from Latin meaning offspring.

Week nine to twelve of pregnancy

Your developing baby, now officially a foetus, measures approximately 5.4 cm from head to bottom, akin to the size of a plum.

Internal organs and muscles have matured significantly, and the heartbeat is detectable through ultrasound scans. Meanwhile, the skeletal structure is transitioning from soft tissue to hardened bone.

The sex organs have taken shape, although determining the baby’s sex via ultrasound scans may still be challenging at this stage, requiring further development before it becomes clearer.

Why Is the First Trimester of Pregnancy Important?

The first trimester is fundamental to the development of the foetus’ major organs and bodily developments.

What Are the Commonly Observed Symptoms During the First Trimester?

The first trimester is marked by a multitude of physical changes to a woman’s body. These hormonal changes may trigger specific symptoms in an expectant woman. For example:

Nausea or vomiting (morning sickness)
Breast tenderness
Frequent urination
Headaches
Lower back and pelvic pain
Heartburn
Weight gain or loss
Constipation
Food cravings
Mood swings

What Should an Expectant Mother Do During the First Trimester?

You should consult your OBGYN as soon as possible once you find out you are pregnant.

During your initial prenatal visit, expect discussions about establishing your expected delivery date, undergoing an ultrasound, and conducting blood and urine tests.
Take the time to familiarise yourself with the significance of antenatal screening, understanding how it can aid in ensuring a healthy pregnancy.
Adjust your diet to ensure both you and your baby receive adequate nutrition, focusing on consuming a balanced and wholesome diet.
Adhere to your obstetrician’s recommendations concerning prenatal vitamins, which are crucial for supporting your baby’s development.
Stay physically active during the first trimester by following your OBGYN’s guidance on safe, low-impact exercises, helping you maintain fitness while prioritising your baby’s well-being.

Other matters to be practiced:

Stop smoking, avoid alcohol and illegal drug use.
Reduce caffeine intake during pregnancy.
Avoid contact sports and activities that put pressure on your abdomen.
Avoid raw fish (sushi), uncooked or undercooked meats, and unpasteurised milk, cheese, or juice.
Avoid hot tubs and saunas.

Read our comprehensive guide to prenatal care.

Find out what to expect in the second trimester and third trimester of your pregnancy journey.

Make an Appointment at Pantai Hospitals

So, dear mama-to-be, as you embark on this incredible journey through the first trimester, remember to take it all in stride. Embrace the changes, cherish the moments, and most importantly, do not forget to pamper yourself along the way. After all, you are growing a tiny human inside you, and that is nothing short of miraculous!

Get in touch with us to book an appointment with our team of O&G specialists today. We offer a comprehensive medical care including prenatal and postnatal care. Find out more about our Obstetrics and Gynaecology Services at your nearest Pantai Hospital.

Pantai Hospitals have been accredited by the Malaysian Society for Quality in Health (MSQH) for its commitment to patient safety and service quality.