Month by month development of your unborn baby

The growth of your baby is a continuous process that often conveys a sense of awe. The following information will help you understand your baby's rapid growth and highlights milestones in development. (Sizes and weights are approximate).

First Trimester

At the end of 4 weeks:

• Embryo is 1/4 inch in length
• Heart, digestive system, backbone and spinal cord begin to form
• Placenta (sometimes called "afterbirth") begins developing
• The single fertilized egg is now 10,000 times larger than size at conception

At the end of 8 weeks: Embryo is 1-1/8 inches in length Eyes, nose, lips, tongue, ears and teeth are forming Penis begins to appear in boys Embryo is moving, although the mother cannot yet feel movement Heart is functioning

At the end of 12 weeks:

• Fetus is 2-1/2 to 3 inches long
• Weighs about 1/2 to 1 ounce
• Nails start to develop and earlobes are formed
• Fetus develops recognizable form
• Arms, hands, fingers, legs, feet and toes are fully formed
• Eyes are almost fully developed
• By this stage, a fetus has developed most of his/her organs and tissues
• Fetal heart rate can be heard at 10 weeks with a special instrument called a Doppler

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Second Trimester

At the end of 4 months:

• Fetus is 6-1/2 to 7 inches long
• Weighs about 6 to 7 ounces
• Fetus is developing reflexes such as sucking and swallowing. Fetus may begin sucking his/her thumb
• Tooth buds are developing
• Sweat glands are forming on palms and soles
• Fingers are well defined
• Sex is identifiable
• Skin is bright pink, transparent and covered with soft, downy hair
• Although recognizably human in appearance, the baby would not be able to survive outside the mother's body

At the end of 5 months: Fetus is 8 to 10 inches long Weighs about 1 pound Hair begins to grow on his/her head Soft, woolly hair called lanugo will cover baby's body (and some may remain until a week after birth when it is shed) Mother begins to feel fetal movement Internal organs are maturing Eyebrows, eyelids and eyelashes appear

At the end of 6 months:

• Fetus is 11 to 14 inches long
• Weighs about 1-3/4 to 2 pounds
• Eyelids begin to part and eyes open occasionally for short periods of time
• Skin is covered with protective coating called vernix
• Fetus is able to hiccup

Third Trimester

At the end of 7 months:

• Fetus is 14 to 16 inches long
• Weighs about 2-1/2 to 3-1/2 pounds
• Taste buds have developed
• Fat layers are forming
• Organs are maturing
• Skin is still wrinkled and red
• If born at this time, he/she will be considered a premature baby and require special care

At the end of 8 months: Fetus is 16-1/2 to 18 inches long Weighs about 4 to 6 pounds Overall growth is rapid this month Tremendous brain growth occurs at this time Most body organs are now developed with the exception of the lungs Movements or "kicks" are strong enough to be visible from the outside Kidneys are mature Skin is less wrinkled Fingernails now extend beyond fingertips

At the end of 9 months:

• Fetus is 19 to 20 inches long
• Weighs about 7 to 7 1/2 pounds
• Skin is pink and smooth
• The lungs are mature
• Baby is now fully developed and can survive outside mother's body
• He/She settles down lower in the abdomen in preparation for birth and may seem less active

For further information, review the video The Miracle of Life and the book A Child is Born by Lennart Nielson for a pictorial review of your baby's development.