First trimester

1-3 months

Week 1 & 2 – Gestational Age

Menustrutual cycle has ended and ovulation has begun.

During intercourse Sperm will travel through the cervix and into the fallopian tube.

If conception takes place, the sperm penetrates an egg and creates a single set of 46 chromosomes called a zygote

Divided cells form a morula caused by a fertilized egg that has traveled through the fallopian tube

The morula becomes a blastocyst . the blastocyst will imbed into the uterine lining and begin the embryonic stage.

Week 3 – Gestational Age (Fetal Development – Week 1)

the brain, spinal cord, heart, and gastrointestinal tract develop.

Week 4 & 5 – Gestational Age (Fetal Development – Weeks 2 & 3)

More growth takes place. Arm and leg buds start to become noticeable. The heart developes a steady rhythm. Hormones are being produced due to the placenta.

Week 6 – Gestational Age (Fetal Development – Week 4)
lungs, jaw, nose, and palate begin to form.
Webbed structure on the hand and feet buds will become your toes and fingers.

Brain continues to form
  Week 7 – Gestational Age (Fetal Development – Week 5)
every essential organ has begun to form in the embryo.

The hair and nipple follicles are forming, and the eyelids and tongue have begun formation.
The elbows and toes are more visible as the trunk begins to straighten out.

Week 8 – Gestational Age (Fetal Development – Week 6)

Ears continue to form externally and internally
The embryo now has the same features as an adult human.

Formation of bones start, muscles can contract at this time.

Facial features continue to mature.

Weeks 9 thru 13 – Gestational Age (Fetal Development – Weeks 7 thru 11)
Fetal period begins.

Genitalia form in male or female, but are not noticeable on an ultrasound

The eyelids close and will not reopen until the 28th week of pregnancy.