Understanding Your Pregnant Body: Weeks 1–42

First Trimester (Weeks 1–13) Your body begins major hormonal changes, organ systems start developing, and fatigue is common. Weeks 1–4: Conception & Implantation

  • Not technically pregnant yet (based on LMP)
  • Ovulation and fertilization occur
  • Implantation into the uterus
  • Your body: Hormones like hCG begin rising
  • You may feel: Cramps, bloating, fatigue, mild spotting

Weeks 5–8: Baby’s Foundations

  • Embryo begins forming brain, heart, and spine
  • hCG, progesterone, and estrogen increase
  • Your body: Nausea, breast tenderness, fatigue
  • You may feel: Mood swings, food aversions, emotional sensitivity

Weeks 9–13: From Embryo to Fetus

  • Baby becomes a fetus; limbs, organs, and heartbeat develop
  • Uterus expands and may cause mild bloating
  • Your body: Nausea may peak, hormonal shifts continue
  • You may feel: Constipation, heightened smell, emotional surges

Second Trimester (Weeks 14–27) Often considered the “easiest” trimester—energy returns, baby grows rapidly, and your bump shows.

Weeks 14–18: Baby Moves

  • Organs continue maturing; genitals forming
  • You may feel quickening (baby movements!)
  • Your body: Growing bump, round ligament pain, skin changes Weeks 19–22: Stronger Kicks
  • Anatomy scan can check development
  • Baby’s hair, skin, and limbs grow rapidly
  • Your body: Backaches, weight gain, possible stretch marks

Weeks 23–27: Viability Approaches

  • Baby's lungs and nervous system develop
  • Braxton Hicks contractions may start
  • Your body: Fatigue returns, heartburn, vivid dreams, swelling

Third Trimester (Weeks 28–42) Body preps for labour, baby puts on weight, and discomfort may increase—but so does the bonding.

Weeks 28–32: Baby Fat + Brain Boost

  • Baby’s eyes open and fat forms under skin
  • Your body: Frequent urination, sleep struggles, emotional ups and downs

Weeks 33–36: Final Growth

  • Baby positions head-down
  • Uterus expands to max size
  • Your body: Pelvic pressure, nesting urges, back pain

Weeks 37–40: Full Term

  • Baby’s lungs mature, brain still developing
  • Cervix begins to soften and thin (effacement)
  • Your body: Contractions may start (prodromal labour), increased discharge, “lightening” (baby drops)

Weeks 41–42: Post-Term

  • Baby continues growing; monitoring increases
  • Induction may be discussed if no signs of labour
  • Your body: May feel large, tired, and ready! Watch for labour signs