The First Trimester of Pregnancy

Congratulations! Welcome to one of the most exciting adventures in life – pregnancy. Over the next 40 weeks, you’ll experience remarkable changes in your body. You are now an expectant mother, and it’s completely normal to have many questions and concerns. Questions like, “What will my baby look like?” “Will it be a boy or a girl?” and “Will the baby be healthy?” are just a few of the many that may be on your mind. Pregnancy is a wonderful journey, so sit back (as much as you can) and relax (as much as possible), and savor every moment of this adventure!

The first trimester of pregnancy spans from the 1st week to the 13th week (from conception). Initially, determining the exact number of weeks can be tricky. In most women, a menstrual cycle is 28 days long. However, normal cycles can range from 21 to 35 days in adult women and from 21 to 45 days in young women. Ovulation typically occurs between days 11 and 21 of the menstrual cycle when an egg is released from the ovaries. During this time, the uterus prepares itself for pregnancy. The egg can be fertilized by sperm within approximately 12-24 hours. If fertilization doesn’t occur, both the egg and the prepared uterine lining are shed as menstrual bleeding. Once fertilization takes place, the zygote contains 46 chromosomes – 23 from you and 23 from your partner. These chromosomes contain thousands of genes that determine characteristics like the baby’s sex, eye and hair color, body measurements, and facial features. Fertilization is now complete.

Most women may not know the exact date of ovulation, even though they know their last menstrual period (LMP). Therefore, pregnancy is calculated based on the first day of the LMP. In other words, the start date of pregnancy is considered to be the first day of the LMP.

The 3rd week of pregnancy is when your pregnancy truly begins. During this week, the fertilized egg enters the uterus. At this stage, your baby is a cluster of 13-32 undifferentiated cells, known as a morula. It’s surrounded by trophoblast cells that will later form the placenta, which is your baby’s lifeline. This cluster, made up of morula, trophoblast cells, and fluid, is called a “blastocyst.” The blastocyst releases enzymes as it attaches to the uterine wall, creating a cozy home for itself. This attachment usually occurs around the 12th day after fertilization. Sometimes, slight spotting or bleeding can happen during this implantation process. Around 14 days after fertilization (in the 4th week of pregnancy), your baby is about 1 mm in size and consists of three layers. These layers will eventually develop into organs and tissues.

Around 4 days after fertilization, the pregnancy hormone hCG (human chorionic gonadotropin) starts being produced. HCG stimulates the ovaries to produce more estrogen and progesterone. Initially, hCG can be detected in the blood and later in the urine. Home pregnancy tests become positive around 6-12 days after fertilization. At this point, your baby has just completed its journey from the fallopian tubes to the uterus. During implantation, you might experience a yellowish discharge or sometimes spotting, which is quite common. Miscarriages are relatively common during this early stage, often occurring before a woman even realizes she’s pregnant. Researchers believe that three out of every four pregnancy losses are due to implantation failure. Exposure to infections, alcohol, medications, and chemicals during these early weeks can contribute to these losses.

You’ve taken a home pregnancy test, and it’s positive. Now it’s time for your first prenatal appointment. This initial visit is crucial for assessing your overall health, identifying any risk factors that could affect you and your baby, and sometimes, confirming the presence of the gestational sac in your uterus. If the sac isn’t visible, further hCG monitoring may be necessary.

Now that you have received the big news, your journey has begun. Congratulations!

This is a crucial moment in your life and in the development of your baby. The first few months of pregnancy can be the most challenging.

From the 5th week to the 8th week, your baby’s cells rapidly develop and gain multiple functions. Your baby’s heart, brain, spinal cord, muscles, and skeletal system begin to develop during these months.

In the 5th week, the brain, spinal cord, nerves, and spine begin to develop. The spine closes along the midline of the fetus. Towards the end of the week, the heart and circulatory system start to develop. The first heartbeat is observed around 21-22 days after fertilization, although it may not always be detectable with ultrasound. At this stage, your baby is approximately 1.5 mm in length.

In the 6th week, your baby’s face starts to take shape. The optic nerve begins to form, followed by the formation of the eyes and ears. In the 6th week, the neural tube completely closes. The brain continues to grow rapidly. The fetal heart starts pumping blood and acquires a regular rhythm. The digestive and respiratory systems begin to develop. Later in this week, buds that will later form the arms, legs, fingers, and toes become visible. At this point, the length of the baby is about 3 mm.

In the 7th week, your baby’s umbilical cord begins to form. The umbilical cord is a vascular structure made up of two veins and one artery. It carries nutrient-rich blood to your baby. The circulation from mother to baby and back again takes about 30 seconds. Meanwhile, the brain continues to develop and become more complex. The fetal face becomes more distinct. Mouth formation and ear indentations occur. The iris, the colored part of the eye, starts to develop. Legs, feet, arms, and hands begin to form, and fingers start to develop. At this week, the baby is approximately 8 mm in length.

In the 8th week, fingers of the hands and feet start to form, although there’s a webbing between them. Arms and legs start to elongate and become more defined. Wrists and elbows form. Eyelids have developed. Ears, upper lip, and nose become recognizable. The digestive system and the heart continue to develop. The fetal heart rate reaches about 150 beats per minute. Your baby is approximately 1.2 cm in length.

“I am very excited about being pregnant, but I feel very tired. I find myself sleeping all day. But when I wake up, I still feel tired. I feel exhausted.”

During the second month of pregnancy, tremendous changes occur in your body. Changes in hormones during pregnancy affect other organ functions. Nausea and vomiting are the most common complaints during pregnancy. Increased progesterone slows down food passage through the digestive tract. Additionally, the digestive system muscles relax. As a result, complaints like bloating, abdominal distention, indigestion, reflux, and constipation can occur. Vitamins and iron supplements may worsen these complaints. In some women, an increase in saliva production due to hormones can cause gum bleeding. These discomforts are part of the normal process.

Your body increases blood production to carry more oxygen to your baby. Your blood volume increases. Your heart pumps more strongly and rapidly. Additionally, there’s vasodilation in your vessels to increase blood flow to your baby. These changes cause a feeling of thirst, headache, dizziness, and fatigue.

Breast tenderness is one of the earliest signs of pregnancy. Due to hormonal changes, milk ducts develop to feed the baby. This development continues in the first three months. Pain can be reduced with less tight and supportive cotton bras. Changes in the breasts and enlargement of the ring around the nipple occur due to increased pigment from hormones.

At the beginning of pregnancy, an increase in vaginal discharge is observed due to hormones. This discharge is thin and milky in color. You can use pads for this discharge, but tampons are not recommended due to the risk of infection. If your discharge is green or yellow and has a strong odor, you should definitely consult your doctor.

Frequent urination is another sign of pregnancy. Increased blood volume leads to increased urination, and the growing uterus puts pressure on the bladder. As a result, the need for toilet increases. Avoiding caffeine-containing foods like coffee, which stimulate the bladder before bedtime, can reduce urinary frequency.

Increased fatigue and changing hormones can affect your mood. You may find yourself suddenly feeling sad or restless despite being happy. You may experience crying spells for no reason and an overly sensitive attitude. This is a natural process. Spend time with your loved ones and don’t hesitate to seek help from them.

“Now is the time to share the happy news with your family and friends!”

The most vulnerable period of pregnancy is starting to pass after this month. The risk of pregnancy-related issues begins to decrease.

In the 9th week, your baby’s head is relatively large, and it seems pressed against the chest. Finger formation in the hands and feet continues, although there is a membrane between the fingers. Arms and legs start to lengthen and become more defined. Wrists and elbows form. Eyelids have developed. Ears, upper lip, and nose become recognizable. The digestive system and the heart continue to develop. The fetal heart rate reaches about 150 beats per minute. Your baby is approximately 22 mm in length.

In the 10th week, all of your baby’s internal organs begin to take shape. The embryonic tail at the baby’s buttocks has disappeared. Finger buds that will form the milk teeth start to develop. The external genital organs start to develop. The baby’s head length equals one-third of the body’s length. Your baby is about 35 mm in length.

In the 11th week, the placenta continues to develop rapidly. All internal organs are in place and continue to grow rapidly. Ears move upward and take their normal positions. External genital organs begin to develop. The length of your baby’s head is equal to the length of the body. Your baby is approximately 60 mm in length.

In the 12th week, your baby is fully formed. All organs, muscles, arms, legs, fingers, and toes are in their places, and the sexual organs have developed. Organogenesis, the formation of organs, is complete. With this week, in cases where necessary, drug use becomes safer. Your baby’s skeletal system is made of cartilage and is beginning to harden into bone. Nails have formed. The baby’s head is about one-third the length of the body. Your baby is about 6 cm in length.

“My body is preparing me for motherhood by reminding me of my childhood. I eat something every three hours! I crave things I don’t need, and I cry because I’m so tired! I feel like the world is revolving around me!”

After this month, these troubles will diminish, and you’ll start feeling better.