Pregnancy trimesters refer to the number of weeks during pregnancy leading up to childbirth. A complete pregnancy consists of three trimesters and typically spans approximately 40 weeks from the initial day of the last menstrual period. Throughout each trimester, the fetus undergoes significant developmental milestones.

Although the expected duration is 40 weeks, a full-term baby can be delivered as early as 37 weeks or as late as 42 weeks.

  1. First trimester: 1–12 week

2. Second trimester: 13–28 weeks

3. Third trimester: 29–40 weeks

The first trimester

The initial stage of pregnancy, known as the first trimester, encompasses the initial 12 weeks and holds immense significance for the development of the fetus.

The fetus

Following conception, the fusion of the egg and sperm results in the formation of a zygote, which subsequently implants itself into the uterine wall. As the cells of the zygote divide and multiply, it transforms into an embryo.

This is what happens at the end of 12 weeks.

  1. During this stage, significant progress is observed in developing the major organs and structures within the body.
  2. The heart beats rhythmically, and the formation of fingers and toes is evident.
  3. At approximately 3 inches long and weighing nearly 1 ounce, the fetus starts to exhibit coordinated movement as its nerves and muscles work together.
  4. It can even make a fist.
  5. Additionally, eyelids form, which will remain closed until around week 28 to safeguard the developing eyes.

The Woman’s Experience

Throughout the first trimester of pregnancy, individuals undergo numerous changes, with one notable occurrence being morning sickness, which commonly persists throughout this stage and occasionally extends beyond. Additionally, several other changes include:

  1. fatigue
  2. tender, swollen breasts
  3. mood changes
  4. cravings for certain foods
  5. headaches
  6. indigestion
  7. a need to urinate more often
  8. weight changes
  9. constipation
  10. nausea

The second trimester

The second trimester has significant fetal development from weeks 14 to 27. During this time, the fetus experiences substantial growth, reaching a length of approximately 1 foot and weighing around 1.5 pounds.

The fetus

This is what happens by the end of the second trimester

    1. Meconium, the initial bowel movement, develops in the intestines.
    2. The fetus gains the ability to see, hear, make sucking motions, and even scratch itself.
    3. Skin, hair, and nails have formed.
    4. Although the lungs have developed, they are not yet functional.
    5. The fetus establishes regular sleep and wake patterns.
    6. In males, the testicles descend into the scrotum, while in females, eggs form in the ovaries.
    7. Taste buds have emerged.
    8. The bone marrow produces blood cells.
    9. The body of the fetus is covered with fine hair called lanugo.

The Woman’s Experience

Towards the conclusion of the second trimester, it is common for the symptoms of morning sickness and fatigue to diminish or vanish altogether. It becomes feasible to perceive the movements of the baby within the uterus.

Here are the new changes that are taking place:

    1. Stretch marks might emerge on the abdomen, thighs, breasts, and buttocks.
    2. The areola, the skin surrounding the nipples, tends to darken.
    3. Patchy darkening of the facial skin may occur.
    4. Swelling may be observed in the ankles, fingers, and face.
    5. Itching may manifest. If accompanied by vomiting or jaundice (yellowing of the skin or whites of the eyes), it is advisable to seek medical guidance.

The third trimester

The third trimester encompasses the period from week 29 until delivery, typically occurring around week 40.

The fetus

By this stage, most organs and body systems have already developed and will continue to grow and mature. As the pregnancy progresses towards delivery, the fetus descends lower in the person’s abdomen and typically assumes a head-down position.

During this trimester,

    1. The bones of the fetus undergo a process of hardening.
    2. Movements of the fetus become more pronounced and noticeable.
    3. The eyes are open and can respond to light stimuli.
    4. The formation of the lungs reaches completion, preparing them for independent breathing after birth.
    5. The fine hair covering the fetus, known as lanugo, starts to shed, while a protective
    6.  waxy coating called vernix develops on the skin.

    The Woman’s Experience

    During this period, as the fetus continues to grow, it can lead to new discomfort for the woman, who may experience the following symptom

  1. heartburn
  2. shortness of breath
  3. swelling in the ankles, face, and fingers
  4. insomnia
  5. mood changes
  6. leakage of milk from the breasts
  7. other breast and nipple changes
  8. frequent urination
  9. haemorrhoids
  10. Braxton-Hicks contractions, which do not indicate labour
  11. real contractions, which indicate labour

The fourth trimester

This period is commonly referred to as the postpartum period, which spans the three months following delivery and holds great significance for the health of both the individual and the baby. Some refer to this transitional phase as the fourth trimester.

While it is an exciting time, the postpartum period can bring about various challenges due to hormonal and environmental changes. These challenges may include:

    1. Recovery after delivery, particularly if there are stitches involved.
    2. Coping with lochia, a discharge of blood and tissue that can persist for several weeks.
    3. Experiencing cramping, which may resemble menstrual cramps, especially while breastfeeding.
    4. Adjusting to the new role of parenthood and learning new skills associated with caring for a newborn.
    5. Dealing with sore breasts and other breastfeeding difficulties.
    6. Experiencing fatigue due to sleep deprivation and other factors.
    7. In certain cases, grappling with postpartum depression is a condition that requires attention and support.

Here are some recommended measures to manage the well-being of women who have recently given birth:

    1. If beneficial, limit the number of visitors.
    2. Seek assistance from others when needed.
    3. Minimize household chores and responsibilities.
    4. Rest whenever the baby is resting.
    5. Maintain regular and balanced eating habits as much as possible.
    6. Share concerns regarding the baby’s well-being, breastfeeding, or personal health with healthcare professionals.
    7. Attend all scheduled follow-up appointments to monitor progress and address any potential issues.

    RecommendedBirth Plan: The Best Guide To Creating a Birth Plan


The journey of pregnancy, childbirth, and the initial months with a newborn is an unparalleled phase in life. Unique experiences, emotions, significant uncertainties, and transformative changes characterize it.

Receiving consistent prenatal care throughout each trimester is of utmost importance. A healthcare provider plays a crucial role in ensuring that the fetus achieves their developmental milestones while safeguarding the overall health of the pregnant individual.