Note: Information provided on this page is for reference only,
please seek medical assistance when in doubt
First trimester begins at day 1 of your last menstrual cycle till week 12. During the first
trimester of pregnancy, the woman undergoes many physiological and hormonal changes, including
cardiovascular, hematologic, metabolic, renal and respiratory changes. This changes occurs in your
body to ensure the fetus is provided for blood sugar, breathing and cardiac output. Levels of
progesterone and oestrogens rise continually throughout pregnancy, suppressing the hypothalamic
axis and subsequently the menstrual cycle. Hormonal changes affect almost every organ system
in your body.
Other noticeable changes you may experience:
With changes in your body, you might need to make changes to your daily routine, such as going
to bed earlier or eating frequent small meals. Fortunately, most of these discomforts will go
away as your pregnancy progresses.
- Extreme tiredness
- Tender and/or swollen breasts, your nipples might also stick out.
- Upset stomach with or without throwing up (morning sickness)
- Cravings or distaste for certain foods
- Mood swings
- Constipation (trouble having bowel movements)
- Need to pass urine more often
- Weight gain or loss
Baby growth in first trimester
At 4 weeks:
- Baby's brain and spinal cord have begun to form.
- Heart begins to form.
- Arm and leg buds appear.
- Your baby is now an embryo and one-twenty-fifth inch long.
At 8 weeks:
- All major organs and external body structures have begun to form.
- Baby's heart beats with a regular rhythm.
- Arms and legs grow longer, and fingers and toes have begun to form.
- Umbilical cord is clearly visible.
- Eyes have moved forward on the face and eyelids have formed.
- Sex organs begin to form.
- At the end of eight weeks, baby looks more like a human nearly 1 inch long and weighs
less than one-eighth ounce.
At 12 weeks:
- The nerves and muscles begin to work together.
- Your baby can make a fist.
- Eyelids close to protect the developing eyes; however eyelids do not open until the 28
- External sex organ shows up and boy or girl baby is distinguishable.
- Growth of head has slowed, and your baby is now much longer about 3 inches long, and weighs
almost an ounce.