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How Big is Your Baby This Week?

Get a sense of your baby's approximate length and weight from conception to birth with our week-by-week averages.
poppy seeds Week 4

Your fertilized egg, known as a zygote, is a ball of 32 cells that's about the size of a poppy seed. It's at this stage that the cells separate into three distinct layers from which your baby's internal organs and skin will develop.

Baby's Length: about 0.014 to 0.04 in.

Baby's Weight: less than 0.04 oz.