Three Weeks 1/5”, .0001 oz.
Embryo’s brain, spinal sord, heart, and blood vessels begin to develop.
One Month ¼”, .001 oz.
Embryo’s nervous and circulatory systems begin to form. Kidneys star to develop. Tissues for muscles and bones, digestive tract and the eyes, ears, and mouth begin to develop. The crude heart beats regularly. Baby possesses the beginnings of all major organs.
Six Weeks 1/2”, .01 oz.
Face takes shape. Buds for arms, legs, backbone, and liver begin to form. Upper and lower jaws develop
Two Months 1”, 1/30 oz.
Fetus has clearly defined eyes, ears, nose, and arms. The hands have fingers and the feet have toes. Cartilage forms, and bones begin to distinguish themselves. The fetus moves, but the mother cannot yet feel these movements.
Three Months 3”, 1 oz.
Tooth buds begin to form inside the jaw. Vocal cords start to take shape, and all organs become better defined, more precise, and functional. Fingernails and toenails form. Nostrils close, eyelids fuse shut. Liver begins to produce red blood cells. Sex organs become defined.
Four Months 61/2”, 4 oz.
Fetus’s movements become more pronounced and mother may feel a slight flutter. Fetus swallows and excretes amniotic fluid. Early fecal matter, called meconium, collects in fetus’s intestinal tract. Nearly all organs are formed. Fine hair covers body. Obsetrician can detect a heartbeat using amplified stethoscope.
Five Months 12”, 1 1/2 lbs.
Fetus develop hair, eyebrows, lashes, facial expressions, and begins to move vigirously and frequently. Mother can feel definite fetal movements. Most organ systems function, first
Five months (continued)
Sucking responses appear, fetus grips with hands. Eyelids are still fused shut, but blinking like movements begin
Six Months 15”,2 ½ lbs.
Fetus’s skin, nails, and hair take on adult form. Fat cells begin to form and vernix – the oily substance that protects the baby from the amniotic fluid – develops. Nostrils reopen, and the baby begins to make muscular breathing motions. The fetus demonstrates brain-wave patterns, and crude hearing and vision systems are present.
Seven Months 16 ½”, 4 lbs.
Fetus’s eyes are completely formed and can perceive light. The eyelids reopen. Taste buds on tongue are functional. Organs continue to mature. Nerve cells mature, fetus continues to lay down fat cells.
Eight Months 18”, 5 ½ lbs.
Nervous system undergoes further development. Fatty sheath, called myelin, forms around nerve fibers. Fetus continues to grow in length, weight, and strength.
Nine Months 20”, 7 ½ lbs.
Lungs prepare to function independently. Fetus continues to grow in length, weight, and strength.
The nutritional needs of pregnant women increase dramatically both because of the rapid fetal growth and because of changes in the mother’s body necessary to nourish the fetus and promote breast milk production. Pregnant women, therefore, need more calories overall and more of each nutrient.
Current understanding of how much weight should be gained during pregnancy contradicts theories in vogue before 1970. For the Past several centuries, many doctors have encouraged women to restrict weight gain while pregnant to a maximum of 18 pounds. At the time, this advice made sense: the mortality rate of women at birth was high, and smaller babies were more easily delivered. Now, however, it is recognized that somewhat larger babies – from 6 pounds 10 ounces to 9 pounds 14 ounces – are more likely to survive and have fewer complications at birth.
Women whose weight is normal prior to conception should gain between 22 and 28 pounds during pregnancy. Women who are underweight before conception can gain up to 30 pounds, and obese women should gain approximately 16 pounds. A minimum of 15 pounds should be gained because studies show that infant mortality rates double when maternal weight gain is inadequate.
The baby itself accounts for only one-third or less of the total weight gain; a quarter goes to tissues surrounding the baby – placenta, amniotic fluid, and uterus; and slightly less than half is needed by the mother. The mother’s blood supply increases during pregnancy, from approximately 8 ½ to 11 pints, as she supplies blood to the placenta and the baby. During pregnancy, fatty tissue increases and is redistributed in the abdomen, back, and upper thighs in preparation for the demands made by the rapid growth of the baby during the last trimester and the high energy expenditure at the time of delivery and while breast feeding.
Most of the baby’s growth occurs during the final trimester. The mother gains little weight during the first trimester, generally only 1 ½ to three pounds. Beginning with the second trimester, however, mothers should gain approximately one pond every seven to nine days. In general, a mother’s low weight gain during the last trimester will mean a smaller baby, with smaller organs – smaller brain, heart, kidney, and liver.
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