First Trimester: Baby Growth
Your baby is growing and developing rapidly. While you will be unaware of any of these changes, early ultrasounds show just how active and developed your little one becomes in the first few months!
WEEKS 1-4 OF PREGNANCY
- The dividing fertilized egg moves down the Fallopian tube toward the uterus.
- At about 5 days after fertilization, the cluster of dividing cells enters the uterus.
- At about 8–9 days after fertilization, the cluster of cells (now called a blastocyst) attaches to the lining of the uterus.
WEEKS 5-8 OF PREGNANCY
- The placenta begins to form.
- The brain and spinal cord begin to form.
- The tissues that will form the heart begin to beat.
- The heartbeat can be detected during an ultrasound exam at about 6 weeks of pregnancy.
- Buds for limbs appear with paddle-like hands and feet.
- The eyes, ears, and nose begin to develop.
- Eyelids form, but remain closed.
- The genitals begin to develop.
- By the end of the eighth week, all major organs and body systems have begun to develop.
WEEKS 9-12 OF PREGNANCY
- Buds for future teeth appear.
- Fingers and toes start to form.
- Soft nails begin to form.
- Bones and muscles begin to grow.
- The intestines begin to form.
- The backbone is soft and can flex.
- The hands are more developed than the feet.
- The arms are longer than the legs.