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Trimester 1
includes weeks 1,2,3 prenatal development. -
Prenatal development week 1
The lining of your uterus thickens to prepare for pregnancy. You may notice sticky vaginal discharge during ovulation. At the beginning of your period, about 20 eggs called ova occupy fluid-filled sacs called follicles. -
prenatal development week 2
In your ovary, an egg is maturing and getting ready to break free. Meanwhile, the lining of your uterus is growing and getting thicker to accept and nourish a new life. At the end of the week, ovulation will occur as your ovary releases the egg into your fallopian tubes. -
prenatal development week 3
Your developing baby is a tiny ball (called a blastocyst) of several hundred cells that are multiplying and burrowing into the lining of your uterus. The cells in the middle will become the embryo. -
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Trimester 2
Includes weeks 4,5,6 of prenatal development. -
prenatal development week 4
The embryo grows and develops within the lining of your womb. The outer cells reach out to form links with your blood supply. The inner cells form into 2, and then later into 3 layers. -
prenatal development week 5
The brain and spinal column are already starting to form. The spinal cord is called the neural tube and is developing as an open groove. Your baby's head is much larger than the rest of the body at this stage as the brain and face are developing very rapidly. Your baby's heart will start beating this week. -
prenatal development week 6
The baby's brain and spinal cord will develop from the neural tube. The heart and other organs also are starting to form. Structures necessary to the formation of the eyes and ears develop. Small buds appear that will soon become arms. -
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Trimester 3
Includes weeks 7,8,9 prenatal development. -
prenatal development week 7
The embryo has grown to about 10mm long from head to bottom. This measurement is called the crown-rump length. The brain is growing rapidly and this results in the head growing faster than the rest of the body. The embryo has a large forehead, and the eyes and ears continue to develop. -
prenatal development week 8
This week, hands and feet are forming tiny fingers and toes, and those arms are able to flex at the elbows and wrists. At this point, eyes begin to develop pigment, and genitals are forming too, although it's still too soon to know whether you're expecting a boy or a girl. -
prenatal development week 9
The embryo is about 1.7 cm long, from head to tail. The head looks much more like a baby's head now, although it's big compared to the rest of the body. The facial features are more defined. The external and middle ear are taking shape, but babies can't hear until about 24 weeks.