Pregnancy: The Three Trimesters

The Three Trimesters
Trimesters are the three distinct time periods that makeup pregnancy. The majority of women experience various physical and psychological changes with each trimester. It is important to know that each woman is unique and experiences signs and symptoms differently.
A full-term pregnancy lasts about 40 weeks starting on the first day of a woman's last period. Each of the trimesters lasts between 12 and 14 weeks. The fetus will reach particular developmental milestones in each trimester.
The First Trimester (0 to 13 Weeks)
The most essential period for the growth of your unborn child is the first trimester. Your baby's bodily structure and organ systems grow throughout this time. During this time, the majority of miscarriages and birth abnormalities happen.
During the first trimester, significant changes to your body also take place. Numerous symptoms, such as nausea, exhaustion, breast discomfort, and frequent urination, are frequently brought on by these changes. Even though these are typical pregnant symptoms, every woman's experience is unique. For instance, while some people may feel more energized during this time, others may feel extremely exhausted and emotional.
The Second Trimester (14 to 26 Weeks)
The second trimester of pregnancy is frequently referred to as the "golden period" because many of the unpleasant symptoms of an early pregnancy vanish at this time. You're probably less likely to feel sick, sleep better, and have more energy throughout the second trimester. A completely other set of symptoms, such as heartburn, leg cramps, constipation, back discomfort, and abdominal pain, could, however, appear.
You may detect your baby's first fluttering motions between 16 and 20 weeks.
The Third Trimester (27 to 40 Weeks)
As you approach the end of your pregnancy, you likely feel eager and enthusiastic about the arrival of your child. Breathing difficulties, hemorrhoids, urine incontinence, varicose veins, and sleep issues are a few of the physical symptoms you could have at this time. The fact that your uterus grows from roughly 2 ounces before pregnancy to 2.5 pounds at delivery is the cause of many of these symptoms.
Prenatal Care Throughout the Three Trimesters
The best prenatal care attainable ensures both the well-being of the mother and the unborn child.
If you think you might be pregnant, schedule a consultation with your doctor to talk about prenatal care. The number of visits you'll require depends on numerous factors, including your own health and your doctor's preferences.
Prenatal checks are necessary to identify any potential problems, resolve any issues, and monitor your baby's growth and development. You could require additional prenatal care if you already have a medical condition, such as diabetes, or if there are complications throughout your pregnancy.
In a healthy pregnancy, appointments are scheduled around significant milestones and testing. During visits, your doctor will also provide you with critical information regarding the status of your pregnancy and assist you in getting ready to give birth.
Prenatal Tests
The most typical prenatal tests are described below, along with information on how often they occur and what to anticipate throughout the trimesters:
-
Genetic Carrier Screening
- When is it done: Prior to or during pregnancy
- How it works: A blood test is performed to determine whether you carry a genetic alteration that could increase the chance of a genetic problem in your unborn child. Cystic fibrosis and spinal muscular atrophy are two disorders that are routinely checked for.
-
Prenatal Screening
Prenatal screening combines two blood tests, which are carried out at various stages of pregnancy:
Test one – NIPT:
- When is it done: 10 weeks or later
- Cell-free DNA screening, also known as noninvasive prenatal testing, or NIPT, is carried out to ascertain a baby's risk for Down syndrome and two other syndromes, trisomy 18 and trisomy 13, as well as other genetic conditions. It can also foretell the sex of your unborn child.
Test two – Maternal serum alpha-fetoprotein (MASFP) screening
- When is it done: Between 15 and 21 weeks of pregnancy
- A maternal serum alpha-fetoprotein (MASFP) screening is performed to determine the likelihood of abnormalities of the spine (neural tube defects) or abdomen (abdominal wall defects).
-
Nuchal Translucency
- When is it done: Between 12 and 14 weeks of pregnancy
- How it works: An abdomen ultrasound analyzes the volume of fluid behind the baby's neck to check for structural issues including heart abnormalities as well as certain genetic diseases. A greater likelihood of chromosome abnormalities, birth malformations, and genetic diseases is indicated by the presence of extra fluid there.
-
Chronic Villus Sampling
- When is it done: Between 10 and 13 weeks of pregnancy
- How it works: To check for any chromosomal or genetic problems, a small sample of the placenta is removed and submitted for analysis.
-
Amniocentesis
- When is it done: Between 16 and 22 weeks of pregnancy
- How it works: The procedure involves the physician taking a tiny sample of the amniotic fluid encircling your unborn child. Genetic examination of the fluid can detect neural tube defects as well as chromosomal or genetic problems.
-
Early Fetal Anatomy Examination
- When is it done: Between and 14 weeks of pregnancy
- How it works: A nuchal translucency ultrasound is one of the numerous physical characteristics of your baby's body that is examined during the first trimester ultrasound. For high-risk patients, such as those who are expecting a child with a suspected abnormality, got high-risk results on a genetic screening test, or had a previous pregnancy with fetal abnormalities, it is typically advised.
-
Anatomy Ultrasound (Level 2)
- When is it done: At or around 20 weeks of pregnancy
- How it works: Your healthcare provider looks at several parts of your baby's body, such as the heart, brain, spine, limbs, and some other organs. The placenta, uterus, and cervix are also evaluated during the anatomy ultrasound examination.
-
Glucose Tolerance Test
- When is it done: Between 24 and 28 weeks of pregnancy
- How it works: The test detects the amount of glucose (sugar) in your blood. Gestational diabetes, a kind of diabetes that can develop during pregnancy and necessitates monitoring, may be indicated by an excessively high blood sugar level.
Other tests include fetal monitoring for the baby’s heartbeats and uterine contractions and Group B step testing for potential infections that may be fatal if left untreated.
To ensure a seamless pregnancy, it remains essential to attend all prenatal appointments in a timely fashion and follow your doctor’s recommendations. Remember, each woman is unique and experiences the trimesters differently. Hence, your ultimate source of credible information remains your healthcare provider.
References
Cuckle, H., & Maymon, R. (2016, February). Development of prenatal screening—A historical overview. In Seminars in perinatology (Vol. 40, No. 1, pp. 12-22). WB Saunders.
Hartwig, T. S., Ambye, L., Sørensen, S., & Jørgensen, F. S. (2017). Discordant non‐invasive prenatal testing (NIPT)–a systematic review. Prenatal diagnosis, 37(6), 527-539.
Nicolaides, K. H. (2004). Nuchal translucency and other first-trimester sonographic markers of chromosomal abnormalities. American journal of obstetrics and gynecology, 191(1), 45-67.
Warsof, S. L., Larion, S., & Abuhamad, A. Z. (2015). Overview of the impact of noninvasive prenatal testing on diagnostic procedures. Prenatal diagnosis, 35(10), 972-979.
Meet our doctors from the Obstetrics & Gynaecology department