First trimester

Week 3 of Pregnancy

Ovulation and fertilization occur. The fertilized egg begins dividing and traveling to the uterus.

Fetal size
Fertilized egg
Length
Not yet measurable
Weight
Not yet measurable

Fetal development

  • Fertilization happens within ~24 hours after ovulation.
  • The zygote divides as it travels down the fallopian tube.
  • By the end of the week it nears the uterus, ready to implant.

Maternal changes

  • Most people feel no symptoms yet.
  • A small amount of implantation bleeding or mild cramping may occur as the embryo embeds.

Recommended checkups

  • A pregnancy test is usually too early to be positive — wait until next week.

Jump to week

Textbook averages. Individual variation is wide and this is not medical advice — confirm with your OB.